INTRODUCTION TO IMAGE
INTRODUCTION TO IMAGE INTERPRETATI
INTERPRETATION
ON
Aerial photographs as well as imagery, obtained by remote sensing using aircraft or Aerial photographs as well as imagery, obtained by remote sensing using aircraft or spacecraft as platform
spacecraft as platforms, have applicability in vs, have applicability in various fields. arious fields. By studying the quaBy studying the qualitative aslitative as well as quantitative aspects of images recorded by various sensor systems, like aerial well as quantitative aspects of images recorded by various sensor systems, like aerial photographs (black-and-white, black-and-white infrared, colour and colour infrared), photographs (black-and-white, black-and-white infrared, colour and colour infrared), multiband ph
multiband photographs, sateotographs, satellite llite data (both pdata (both pictorial and dictorial and digital) includiigital) including thermal ang thermal andnd radar imagery, an interpreter well experienced in his field can
radar imagery, an interpreter well experienced in his field can derive lot of information.derive lot of information. Image
Image InterpretatioInterpretation n
Image interpretation is defined as the act of examining images to identify objects Image interpretation is defined as the act of examining images to identify objects and judge their si
and judge their significance. gnificance. An interpreteAn interpreter studies remoter studies remotely sensed data and attely sensed data and attemptsmpts through logical p
through logical process to derocess to detect, identect, identify, tify, measure anmeasure and evaluate d evaluate the significance the significance ofof environmental and cultural objects, patterns and spatial relationships. It is an information environmental and cultural objects, patterns and spatial relationships. It is an information extraction process.
extraction process.
Anyone who looks at a photograph or an imagery in order to recognize an image is an Anyone who looks at a photograph or an imagery in order to recognize an image is an interpreter.
interpreter. A A soil soil scientist, scientist, a a geologist geologist or or a a hydrogeologist, hydrogeologist, a a forester forester or or a a planner,planner, trained in image interpretation can recognize the vertical view presented by the ground trained in image interpretation can recognize the vertical view presented by the ground objects on an aerial photograph or a satellite image, which enables him or her to detect objects on an aerial photograph or a satellite image, which enables him or her to detect many small or subtle features that an amateur would either overlook or mis-interpret. An many small or subtle features that an amateur would either overlook or mis-interpret. An interpreter is, therefore, a specialist trained in the study of photography or imagery, in interpreter is, therefore, a specialist trained in the study of photography or imagery, in addition to
addition to his or her owhis or her own discipline. n discipline. The present The present discussion maindiscussion mainly pertains tly pertains to theo the techniques of visual interpretation, the application of various instruments and the techniques of visual interpretation, the application of various instruments and the extraction of
extraction of information.information.
Aerial photographs, as well as imagery, obtained by remote sensing employing Aerial photographs, as well as imagery, obtained by remote sensing employing electromagnetic energy as the means of detecting and measuring target/objects electromagnetic energy as the means of detecting and measuring target/objects characteristics, has applicability to various fields because of
characteristics, has applicability to various fields because of four basic reasons.four basic reasons. First
First - - It It represents represents a a larger larger area area of of the the earth earth from from a a perspective perspective view view andand provides a format that facilitates the
provides a format that facilitates the study of objects and study of objects and their relationships.their relationships. Second
Second - - Certain Certain types types of of imagery imagery and and aerial aerial photograph photograph can can provide provide a a 3-D 3-D view.view. Third
Third - - Characteristics of Characteristics of objects objects not not visible visible to to the the human human eye eye can can be be transformedtransformed into images
into images Fourth -
Fourth - It provides It provides the the observer observer with with a a permanent permanent record/reprecord/representation resentation ofof objects
objects at at any any moment moment of of time. time. In In addition, addition, data data is is real-time,real-time, repetitive and, when in digital form, is
repetitive and, when in digital form, is computer compatible for quickcomputer compatible for quick analysis.
BASIC PRINCIPLES OF IMAGE INTERPRETATION BASIC PRINCIPLES OF IMAGE INTERPRETATION
Images and their
Images and their interpretabiliinterpretability ty
An image An image taken taken from the from the air or air or space is a space is a pictorial prpictorial presentation oesentation of the f the pattern of pattern of aa landscape.
landscape.
The pattern The pattern is composed is composed of indicators of indicators of objects aof objects and events that nd events that relate to threlate to thee physical, biological and
physical, biological and cultural componecultural components of the landscapents of the landscape..
Similar Similar conditions, conditions, in in similar similar circumstances circumstances and and surroundingsurroundings, res, reflect sflect similar imilar patterns,patterns, and unlike
and unlike conditions reconditions reflect unlike paflect unlike patterns.tterns.
The The type and amtype and amount of infoount of information that crmation that can be extractean be extracted is proportd is proportional to theional to the knowledge,
knowledge, skill skill and and experience experience of of the the analyst, analyst, the the methods methods used used for for interpretationinterpretation and the analyst's awareness of
and the analyst's awareness of any limitations.any limitations. Factors Governing the Quality of an
Factors Governing the Quality of an image image
In addition to the inherent characteristics of an
In addition to the inherent characteristics of an object itself, the following factorsobject itself, the following factors influence image quality:
influence image quality:
Sensor characteristics (film types, digital Sensor characteristics (film types, digital systems)systems)
Season of the year and time of daySeason of the year and time of day
Atmospheric effectsAtmospheric effects
Resolution of the imaging system and scaleResolution of the imaging system and scale
Image motionImage motion
Stereoscopic parallaxStereoscopic parallax Factors Governing
Factors Governing InterpretabiliInterpretability ty 1.
1. Visual Visual and and mental mental acquity acquity of of the the interpreterinterpreter 2.
2. Equipment Equipment and and technique technique of of interpretatiointerpretationn 3.
3. InterpretatiInterpretation on keys, keys, guides, guides, manuals manuals and and other other aids.aids. Visibility of Objects
Visibility of Objects
The objects on aerial photogr
The objects on aerial photographs or imagery aphs or imagery are representare represented in the form of photoed in the form of photo images in tones of grey in B/W photography and in colour/false colour photography in images in tones of grey in B/W photography and in colour/false colour photography in different colours/h
different colours/hues. ues. This visibility of objects in the imageThis visibility of objects in the images varies due to -s varies due to -a)
Inherent Characteristics of Objects Inherent Characteristics of Objects
In any photographic image forming process, the negative is composed of tiny silver In any photographic image forming process, the negative is composed of tiny silver deposits formed by the action of light on photose
deposits formed by the action of light on photosensitive film during exposurnsitive film during exposure. e. The amountThe amount of light received by the various sections of the film depends on the reflection of of light received by the various sections of the film depends on the reflection of electromagnetic radi
electromagnetic radiation (EMR) from variouation (EMR) from various objects. s objects. This light, after passing thrThis light, after passing through theough the optical system, gives rise to
optical system, gives rise to different tones and textures.different tones and textures.
In visual interpretation, an interpreter is primarily concerned with recognizing In visual interpretation, an interpreter is primarily concerned with recognizing changes in tonal values, thereby differentiating an object of a certain reflective changes in tonal values, thereby differentiating an object of a certain reflective characteristic f
characteristic from another. rom another. However, he However, he must be aware must be aware that the same that the same object underobject under different moisture or illumination conditions, and depending on the wavelength of incident different moisture or illumination conditions, and depending on the wavelength of incident energy, may ref
energy, may reflect a different lect a different amount of light. amount of light. For this reason, a geFor this reason, a general key, based onneral key, based on tone characteristi
tone characteristics of objects, cannot be prcs of objects, cannot be prepared. epared. In such cases, otheIn such cases, other characteristicsr characteristics of objects such as their shape, size and pattern etc. help in
of objects such as their shape, size and pattern etc. help in their recognition.their recognition. Quality of
Quality of Aerial Photography/ImagAerial Photography/Imagery: ery:
The quality of image interpretation depends on the quality of the basic material on The quality of image interpretation depends on the quality of the basic material on which the images are
which the images are formed. formed. Normally, in visual inNormally, in visual interpretation, tterpretation, these images are formhese images are formeded on the photograph and represented in tones of grey or in colours of various hues, chroma on the photograph and represented in tones of grey or in colours of various hues, chroma and values.
and values. A study of the factors, affectinA study of the factors, affecting image quality and characterg image quality and characteristics of images, isistics of images, is essential from an interpreter's point of view.
essential from an interpreter's point of view. The Tonal or Colour
The Tonal or Colour Contrast Between an Image and Its Contrast Between an Image and Its Background Background
Photographic tone contrast is the difference in brightness between an image and its Photographic tone contrast is the difference in brightness between an image and its background.
background. Similarly, in colour Similarly, in colour photography colouphotography colour contrast is the rr contrast is the result of all hue valuesult of all hue valueses and chroma differ
and chroma differences between the imaences between the image and its background. ge and its background. The tonal contrast can beThe tonal contrast can be sufficiently increased with proper filters.
sufficiently increased with proper filters. Image Sharpness Characteristics
Image Sharpness Characteristics
Sharpness is the abruptness with which tone or colour contrasts appear on the Sharpness is the abruptness with which tone or colour contrasts appear on the photograph or image
photograph or imagery. ry. Both tone and sharBoth tone and sharpness enable an interpness enable an interpreter to distipreter to distinguish onenguish one object from another
object from another. . To a large extent, image To a large extent, image sharpness is depensharpness is dependent on the focussindent on the focussingg ability of the op
ability of the optical system. tical system. Image sharpness Image sharpness is closely related is closely related to the resolution of to the resolution of thethe optical system.
optical system.
Stereoscopic Parallax Characteristics Stereoscopic Parallax Characteristics
Stereoscopic parallax is the displacement of the apparent position of an image with Stereoscopic parallax is the displacement of the apparent position of an image with respect to a reference poi
respect to a reference point of observation. nt of observation. Sufficient paraSufficient parallax is necessary in order tollax is necessary in order to distinguish objects from th
distinguish objects from their shadows. eir shadows. Parallax dependParallax depends on the height of an object, flyings on the height of an object, flying height and the stereob
height and the stereobase or its corollary, the foase or its corollary, the forward overlap. rward overlap. Stereoscopic parallaStereoscopic parallax canx can be improved by choosing the right base/height (B/H) ratio.
The above investigation appears to be over simplified as a number of other factors The above investigation appears to be over simplified as a number of other factors can be mentioned wh
can be mentioned which obviously effecich obviously effect the image qualityt the image quality. . However, for the However, for the purpose ofpurpose of simplification, we may conclude that
simplification, we may conclude that other factors influence image quality indirectly throughother factors influence image quality indirectly through their effect on tone, sharpness or
their effect on tone, sharpness or parallax.parallax.
In general, if image motion and exposure times were no problem, we would obviously In general, if image motion and exposure times were no problem, we would obviously use fine grain, high definition, slow photographic material, with an appropriate filter in use fine grain, high definition, slow photographic material, with an appropriate filter in order to get better
order to get better sharpness and contrast.sharpness and contrast.
ELEMENTS OF IMAGE INTERPRETATION ELEMENTS OF IMAGE INTERPRETATION
The word photograph in Greek means to draw with light,
The word photograph in Greek means to draw with light, and a photograph, in fact, isand a photograph, in fact, is nothing more or
nothing more or less than a graphic less than a graphic record of erecord of energy intensitnergy intensities. ies. An image reprAn image representsesents energy reflected, emitted or transmitted from an object in different parts of the energy reflected, emitted or transmitted from an object in different parts of the spectrum.
spectrum.
Image interpretation is essential for the efficient and effective use of the data. Image interpretation is essential for the efficient and effective use of the data. While the
While the above proabove properties of perties of aerial photaerial photographs/imagery ographs/imagery help help an interpran interpreter to eter to detectdetect objects due to their tonal variations, he must also take advantage of
objects due to their tonal variations, he must also take advantage of other important charact
other important characteristics of the objects in ordeeristics of the objects in order to recognize them. r to recognize them. The followingThe following elements of image interpretation are regarded as
elements of image interpretation are regarded as being of general being of general significance, irrespectivsignificance, irrespectivee of the precise nature of
of the precise nature of the imagery and the features it the imagery and the features it portrays.portrays.
Elements of Image Interpretation
Elements of Image Interpretation
Black and White Tone
Black and White Tone
Color
Color
Primary Elements
Primary Elements
Stereoscopic Parallax
Stereoscopic Parallax
Size
Size
Shape
Shape
Texture
Texture
Spatial Arrangement
Spatial Arrangement
of Tone and Color
of Tone and Color
Pattern
Pattern
Height
Height
Based on Analysis
Based on Analysis
of Primary Elements
of Primary Elements
Shadow
Shadow
Site
Site
Contextual Elements
Contextual Elements
Association
Association
Shape Shape
Numerous components of the environment can be identified with reasonable Numerous components of the environment can be identified with reasonable certainty merely by their shape. This is true of both natural features and man-made certainty merely by their shape. This is true of both natural features and man-made objects.
objects.
Size Size
In many cases, the length, breadth, height, area and/or volume of an object can be In many cases, the length, breadth, height, area and/or volume of an object can be significant, whether these are surface features (e.g.
significant, whether these are surface features (e.g. different tree species) or atmosphericdifferent tree species) or atmospheric phenomena
phenomena (e.g. (e.g. cumulus cumulus versus versus cumulonimbus cumulonimbus clouds). clouds). The The approximate approximate size size of of manymany objects can be
Tone Tone
We have seen how different objects emit or reflect different wavelengths and We have seen how different objects emit or reflect different wavelengths and intensities of radi
intensities of radiant energy. ant energy. Such differenceSuch differences may be recorded s may be recorded as variations of pictuas variations of picturere tone, colour
tone, colour or density. or density. which enable which enable discrimination discrimination of many spof many spatial variables, atial variables, for examplefor example,, on land different crop types or at sea water bodies of contrasting depths or temperatures. on land different crop types or at sea water bodies of contrasting depths or temperatures. The terms 'light', 'medium' or 'dark' are
The terms 'light', 'medium' or 'dark' are used to describe variations in tone.used to describe variations in tone.
Shadow Shadow
Hidden profiles may be revealed in silhouette (e.g. the shapes of buildings or the Hidden profiles may be revealed in silhouette (e.g. the shapes of buildings or the forms
forms of of field field boundaries). boundaries). Shadows Shadows are are especially especially useful useful in in geomorphological geomorphological studiesstudies where micro relief features may be easier to detect under conditions of low-angle solar where micro relief features may be easier to detect under conditions of low-angle solar illumination than when the sun is high in the sky. Unfortunately, deep shadows in areas of illumination than when the sun is high in the sky. Unfortunately, deep shadows in areas of complex detail may obscure significant features, e.g. the volume and distribution of traffic complex detail may obscure significant features, e.g. the volume and distribution of traffic on a city street.
Pattern Pattern
Repetitive pattern
Repetitive patterns of both natural s of both natural and cultural features are quite common, which isand cultural features are quite common, which is fortunate because much image interpretation is aimed at the mapping and analysis of fortunate because much image interpretation is aimed at the mapping and analysis of relatively complex features rather than the more basic units of which they may be relatively complex features rather than the more basic units of which they may be composed. Such features include agricultural complexes (e.g. farms and orchards) and composed. Such features include agricultural complexes (e.g. farms and orchards) and terrain features (e.g. alluvial river valleys
terrain features (e.g. alluvial river valleys and coastal plains).and coastal plains).
Texture Texture
Texture is an important image characteristic closely associated with tone in the Texture is an important image characteristic closely associated with tone in the sense that it is a quality that permits two areas of the same overall tone to be sense that it is a quality that permits two areas of the same overall tone to be differentiate
differentiated on the basis of microtonal patterns. d on the basis of microtonal patterns. Common image textureCommon image textures include smooth,s include smooth, rippled, mottled, linea
rippled, mottled, lineated and irregular. ted and irregular. UnfortunatelyUnfortunately, texture analysis tends to be rather, texture analysis tends to be rather subjective, since different interpreters may use the same terms in slightly different ways. subjective, since different interpreters may use the same terms in slightly different ways. Texture is rarely the only criterion of identification or correlation employed in Texture is rarely the only criterion of identification or correlation employed in interpretation. More often it is invoked as the basis for a subdivision of categories already interpretation. More often it is invoked as the basis for a subdivision of categories already established using mor
established using more fundamentae fundamental criteria. l criteria. For example, twFor example, two rock units may havo rock units may have thee the same tone but different textures.
Site Site
At an advanced stage
At an advanced stage in image interpretation, the location of an in image interpretation, the location of an object with respectobject with respect to terrain features of other objects may be helpful in refining the identification and to terrain features of other objects may be helpful in refining the identification and classification of certain p
classification of certain picture contents. icture contents. For example, some trFor example, some tree species are found ee species are found moremore commonly in one topographic situation than in others, while in industrial areas the commonly in one topographic situation than in others, while in industrial areas the association of several clustered, identifiable structures may help us determine the precise association of several clustered, identifiable structures may help us determine the precise nature of the local enterpri
nature of the local enterprise. se. For example, the combinFor example, the combination of one or two tall chimneys, aation of one or two tall chimneys, a large central building, conveyors, cooling towers and solid fuel piles point to the correct large central building, conveyors, cooling towers and solid fuel piles point to the correct identification of a thermal power station.
identification of a thermal power station.
Resolution Resolution
Resolution of a sensor system may be defined as its capability to discriminate two Resolution of a sensor system may be defined as its capability to discriminate two closely spaced obj
closely spaced objects from eaects from each other. ch other. More than mMore than most other piost other picture charactecture characteristics,ristics, resolution depends on aspects of the remote sensing system itself, including its nature, resolution depends on aspects of the remote sensing system itself, including its nature, design and performance, as well
design and performance, as well as the ambient conditions during the as the ambient conditions during the sensing programme andsensing programme and subsequent process
subsequent processing of the acquired data. ing of the acquired data. An interpreter must have a knoAn interpreter must have a knowledge aboutwledge about the resolution of various remote sensing
Stereo-scopic Appearance Stereo-scopic Appearance
When the same feature is photographed from two different positions with overlap When the same feature is photographed from two different positions with overlap between successive images, an apparently solid model of the feature can be seen under a between successive images, an apparently solid model of the feature can be seen under a stereoscope.
stereoscope. Such a model is tSuch a model is termed a sterermed a stereomodel and theomodel and the three-dimee three-dimentional view itntional view it provides can aid interpretation. This valuable information cannot be obtained from a single provides can aid interpretation. This valuable information cannot be obtained from a single print.
print.
In practice, these nine elements assure a variety of ranks of importance. In practice, these nine elements assure a variety of ranks of importance. Consequently, the order in which they may be examined varies from one type of study to Consequently, the order in which they may be examined varies from one type of study to another.
another. Sometimes they caSometimes they can lead to assessment of condition lead to assessment of conditions not directly visible in thens not directly visible in the images, in addition to the identification of features or conditions that are explicitly images, in addition to the identification of features or conditions that are explicitly revealed.
revealed. The process, by which related invisibThe process, by which related invisible conditions are established by inferle conditions are established by inference, isence, is termed "conver
termed "convergence of evidencegence of evidence". ". It is useful, for examIt is useful, for example, in assessing the social classple, in assessing the social class and/or income group occupying a particular neighbourhood or the soil moisture conditions in and/or income group occupying a particular neighbourhood or the soil moisture conditions in agricultural areas.
agricultural areas.
Image interpretation may be very general in its approach and objective, such as in Image interpretation may be very general in its approach and objective, such as in the case of terrain eva
the case of terrain evaluation or land classificaluation or land classification. tion. On other occasions it is highly On other occasions it is highly specific,specific, related to clear-cut goals in such fields as geology, forestry, transport studies and soil related to clear-cut goals in such fields as geology, forestry, transport studies and soil erosion mapping.
erosion mapping. In no instance shIn no instance should the interpould the interpreter fail to take reter fail to take into account featuinto account featuresres other than those for which he or she is specifically searching. Failure to give adequate other than those for which he or she is specifically searching. Failure to give adequate consideration to all aspects of a
consideration to all aspects of a terrain is, perhaps, the commonest source of interpretationterrain is, perhaps, the commonest source of interpretation error.
error.
The interpretation of images is therefore an essentially deductive process, and the The interpretation of images is therefore an essentially deductive process, and the identification of
identification of certain key featcertain key features leads to the reures leads to the recognition of others. cognition of others. Once a suitableOnce a suitable starting point has been selected, the elements listed earlier are considered either starting point has been selected, the elements listed earlier are considered either
consciously or subconsciou
consciously or subconsciously. sly. The completeneThe completeness and accuracy of the ss and accuracy of the results dependresults depends on ans on an interpreter's ability to integrate such elements in the most appropriate way to achieve the interpreter's ability to integrate such elements in the most appropriate way to achieve the objectives that have been set for him or her.
objectives that have been set for him or her.
TECHNIQUES OF IMAGE INTERPRETATION TECHNIQUES OF IMAGE INTERPRETATION
The development of interpretation techniques has been mainly by the empirical The development of interpretation techniques has been mainly by the empirical method.
method. The gap between the photo image on the one hand and the refeThe gap between the photo image on the one hand and the reference level, i.e. therence level, i.e. the level of knowledge in a specific field, in the human mind on the other hand, is bridged by the level of knowledge in a specific field, in the human mind on the other hand, is bridged by the use of
use of image-interimage-interpretation. pretation. The techniques adopted The techniques adopted for one for one disciplidiscipline ne may differ may differ fromfrom those adopted for anothe
those adopted for another. r. The sequence of activiThe sequence of activity and the search method mty and the search method may have to beay have to be modified to suit the
modified to suit the specific requirements.specific requirements.
Image interpretation comprises at least three mental acts that may or may not be Image interpretation comprises at least three mental acts that may or may not be performed
performed simultaneouslysimultaneously:: i)
i) The The measurement measurement of of images images of of objectsobjects ii)
ii) Identification Identification of of the the objects objects imagedimaged iii)
iii) Appropriate Appropriate use use of of this this information information in in the the solution solution of of the the problem.problem.
In visual interpretation, the methodology of interpretation for each separate In visual interpretation, the methodology of interpretation for each separate discipline will depend on :
discipline will depend on :
Kind of information to be Kind of information to be interpretedinterpreted
Accuracy of the results to be obtainedAccuracy of the results to be obtained
The reference level of the person The reference level of the person executing the interpretationexecuting the interpretation
Kind and type of Kind and type of imagery or photographs availableimagery or photographs available
Instruments availableInstruments available
Scale and other requirements of the Scale and other requirements of the final mapfinal map
External External knowledge knowledge available available and and any any other other sensory sensory surveys surveys that that have have been been or or will will bebe made in the near future in the same area.
made in the near future in the same area.
From the scrutiny of the above list, it is evident that no stereotyped approach can From the scrutiny of the above list, it is evident that no stereotyped approach can be prescri
be prescribed for bed for the technithe techniques or ques or the methodthe methodology of ology of photo-interprphoto-interpretation. etation. AnAn interpreter must work out the plan of operations and the techniques depending on the interpreter must work out the plan of operations and the techniques depending on the project's special
project's special requiremenrequirements.ts.
In carrying out this task, an interpreter may use many more types of data than In carrying out this task, an interpreter may use many more types of data than
laboratory measurements, analysis, field work and ground and aerial photographs (or laboratory measurements, analysis, field work and ground and aerial photographs (or imagery) make up this
imagery) make up this collateral material.collateral material. Activities of
Activities of Image-inteImage-interpretation rpretation
Image-interpretation is a complex process comprising physical as well as mental Image-interpretation is a complex process comprising physical as well as mental activities.
activities. This means fThis means familiarity witamiliarity with so wide a vah so wide a variety of stimriety of stimuli that the euli that the even mostven most accomplished interpreter is occasionally dependent on
accomplished interpreter is occasionally dependent on reference materials.reference materials. The refere
The reference material in the fnce material in the form of identificaorm of identification keys is a tion keys is a useful aid in imageuseful aid in image interpretation
interpretation. . Many types of Many types of image inteimage interpretation rpretation keys are keys are available or available or may bemay be constructed depending on the abilities of the interpreter and the purpose to be served by constructed depending on the abilities of the interpreter and the purpose to be served by the
the interpretationinterpretation..
INTERPRETATION KEYS INTERPRETATION KEYS
Scope of image
Scope of image interpretatiinterpretation keys:on keys: There are four types of
There are four types of image interpretation keys:image interpretation keys: An
An Item key Item key , is a key , is a key concerned with the identificatconcerned with the identification of an individual object or condition.ion of an individual object or condition. A
A Subject key Subject key , is a collection of item keys concerned with the identification of principal, is a collection of item keys concerned with the identification of principal objects or conditions within a given subject category.
objects or conditions within a given subject category. A
A Regional Key Regional Key , is a compilation of items or subject keys dealing with the identification of, is a compilation of items or subject keys dealing with the identification of objects or conditions characteristic of a
objects or conditions characteristic of a particular region.particular region. An
An Analogous Area Analogous Area Key Key , is a subject or regional key which has been prepared for an, is a subject or regional key which has been prepared for an accessible area and which by interpretation may be used in the interpretation of objects or accessible area and which by interpretation may be used in the interpretation of objects or conditions in inaccessible areas which exhibit similar characteristics.
conditions in inaccessible areas which exhibit similar characteristics. Technical level image
Technical level image interpretation keys: interpretation keys: A
A Technical Key Technical Key , , is is one one prepared prepared for for use use by by image image interpreterinterpreters s who who have have hadhad professional or technical
professional or technical training or experientraining or experience in the subject concerned.ce in the subject concerned. A
A Non-technical Key Non-technical Key , is one prepared for use primarily by image interpreters who have not, is one prepared for use primarily by image interpreters who have not had
had professional professional or or technical technical training training or or experience experience in in the the subject subject concerned.concerned. Intrinsic character of image
Intrinsic character of image interpretatiointerpretation keys: n keys: A
A Direct Key Direct Key , is a , is a designed primarily for the identification of discrete objects or conditionsdesigned primarily for the identification of discrete objects or conditions directly discernible on images.
An
An Association Key,Association Key, is one designed primarily for the deduction of information not directlyis one designed primarily for the deduction of information not directly discernible on images.
discernible on images.
Manner of organization or presentation of image
Manner of organization or presentation of image interpretatiinterpretation keys:on keys:
All image interpretation keys are based upon diagnostic features of the images of All image interpretation keys are based upon diagnostic features of the images of objects or conditions to be identified
objects or conditions to be identified. . As stated above, depending upon thAs stated above, depending upon the manner in whiche manner in which the diagnostic features are organized, two general types of keys are recognized selective the diagnostic features are organized, two general types of keys are recognized selective and eliminatio
and elimination. n. Selective keys Selective keys are arranged in suare arranged in such a way that the ch a way that the interpreter interpreter simplysimply selects the example corre
selects the example corresponding to the object he is trying to idesponding to the object he is trying to identify. ntify. Elimination keysElimination keys are arranged so that the interpreter follows a prescribed step-wise process that leads to are arranged so that the interpreter follows a prescribed step-wise process that leads to the elimination
the elimination of all items exceof all items except the one he is pt the one he is trying to identrying to identify. tify. Most interpreMost interpretersters consider the latter type of
consider the latter type of key preferable.key preferable.
Selective Keys: Selective Keys: An
An Essay Key Essay Key , is , is one where objone where objects or conditions ects or conditions are described are described in textural foin textural form usingrm using images for illustrations only.
images for illustrations only. A
A File Key File Key , is an item key composed of one or more selected images, with notes concerning, is an item key composed of one or more selected images, with notes concerning their interp
their interpretation. retation. This type of This type of key is generkey is generally assembled for ally assembled for use by an iuse by an individualndividual interpreter.
interpreter. A
A Photo Key Photo Key , , is is an an item item key key composed composed of of one one or or more more selected selected images, images, together together withwith notes concer
notes concerning ning their intheir interpretation, terpretation, assembled for assembled for rapid rrapid reproduction eproduction and distriand distributionbution to other
to other interpreterinterpreters.s. An
An Integrated-selective Key Integrated-selective Key , is one in which images and recognition features for any, is one in which images and recognition features for any individual object or condition, within a subject or regional key, are so associated that by individual object or condition, within a subject or regional key, are so associated that by reference to the appropriate portion of the key
reference to the appropriate portion of the key the object or condition can the object or condition can be identified.be identified. Elimination Keys:
Elimination Keys: A
A Disk Key,Disk Key, is one in which selected images recognitis one in which selected images recognition ion features are groupfeatures are grouped or arranged oned or arranged on one or more disks so tha
one or more disks so that, when the recognition t, when the recognition features are prfeatures are properly operly aligned, all but onealigned, all but one object or condition of the group
object or condition of the group under consideratiunder consideration is eliminated from view.on is eliminated from view. A
A Punch Punch Card Card Key Key , is one in which selected image recognition features are arranged in, is one in which selected image recognition features are arranged in groups on separate punch cards. When
groups on separate punch cards. When the properly selected cards are superimposed upon athe properly selected cards are superimposed upon a coded base, all but
coded base, all but one object or coone object or condition ndition of the subjecof the subject group under t group under consideration consideration isis eliminated from view.
eliminated from view. A
A Dichotomous Key Dichotomous Key , is one in which the graphic or word description assumes the form of a, is one in which the graphic or word description assumes the form of a series of pairs of
A modification of the elimination key is to allow probabilistic rather than absolute A modification of the elimination key is to allow probabilistic rather than absolute identification at an
identification at any step or steps in a sequey step or steps in a sequence of steps. nce of steps. A probabilistic key baseA probabilistic key based on locald on local apriori
apriori statistics, is necessary whstatistics, is necessary where identification canere identification cannot be completed.not be completed.
METHODS OF SEARCH AND SEQUENCE OF INTERPRETATION METHODS OF SEARCH AND SEQUENCE OF INTERPRETATION
In visual interpretation and whenever possible, especially when
In visual interpretation and whenever possible, especially when examining vertical orexamining vertical or nearly vertical photograp
nearly vertical photographs, the scene is viewed stereoscophs, the scene is viewed stereoscopically. ically. The sequence begins withThe sequence begins with the detection and iden
the detection and identification of objects followtification of objects followed by measuremed by measurements of the image. ents of the image. TheThe image is then considered in terms of information, usually non-pictorial, and finally image is then considered in terms of information, usually non-pictorial, and finally deductions are made
deductions are made. . The interpreter should wThe interpreter should work methodically, proceeork methodically, proceeding from generalding from general considerations to specific details and from known to
considerations to specific details and from known to unknown features.unknown features.
There are two basic methods that may be used to study aerial imagery: There are two basic methods that may be used to study aerial imagery: "Fishing expedition" - an examination of each and every object so as not to miss
"Fishing expedition" - an examination of each and every object so as not to miss anything,anything, "Logical search" - qu
"Logical search" - quick ick scanning and selectscanning and selective intensive stuive intensive study.dy.
Sequence of Activities Sequence of Activities
Normally the activities in an
Normally the activities in an image-interpreimage-interpretation sequence include the tation sequence include the following:following:
Detection Detection
Detection means selectively picking out an object or element of importance for the Detection means selectively picking out an object or element of importance for the particular kind of interp
particular kind of interpretation in hand. retation in hand. It is often coupled with recognitiIt is often coupled with recognition, in which caseon, in which case the object is not only seen
the object is not only seen but also recognized.but also recognized. Recognition and
Recognition and Identification Identification
Recognition and identification together are sometimes termed photo-reading. Recognition and identification together are sometimes termed photo-reading. However, they are fundamentally the same process and refer to the process of However, they are fundamentally the same process and refer to the process of classification of an object by means of specific or local knowledge within a known category classification of an object by means of specific or local knowledge within a known category upon an object's detection in
upon an object's detection in a photo-image.a photo-image. Analysis
Analysis
Analysis is the
Analysis is the process of sepprocess of separating or darating or delineating a set elineating a set of similar objof similar objects. ects. InIn analysis, boundary lines are drawn separating the groups, and the degree of reliability of analysis, boundary lines are drawn separating the groups, and the degree of reliability of these lines may be
these lines may be indicated.indicated. Deduction
Deduction
Deduction may be directed to the separation of different groups of objects or Deduction may be directed to the separation of different groups of objects or elements and
evidence is derived mainly from visible objects or from invisible elements, which give only evidence is derived mainly from visible objects or from invisible elements, which give only partial information on the nature of
partial information on the nature of certain correlative indications.certain correlative indications. Classification
Classification
Classification establishes the identity of a surface or an object delineated by Classification establishes the identity of a surface or an object delineated by analysis.
analysis. It includes modifIt includes modification of the surfication of the surface into a pertinenace into a pertinent system for use in fiet system for use in fieldld investigation. Classification is made in order to group surfaces or objects according to those investigation. Classification is made in order to group surfaces or objects according to those aspects that, for a certain point of view, bring out their most characteristic aspects.
aspects that, for a certain point of view, bring out their most characteristic aspects. Idealization
Idealization
Idealization refers to the process of drawing or standardized representations of Idealization refers to the process of drawing or standardized representations of what is actually seen in t
what is actually seen in the photo image. he photo image. This process is heThis process is helpful for the subseqlpful for the subsequent use ofuent use of photograph/imager
photograph/imagery during field investigations and in y during field investigations and in the preparation of base maps.the preparation of base maps. These processe
These processes would be better s would be better explained by takinexplained by taking an example. g an example. If investigationsIf investigations of dwellings are to be carried out, the first step would be to detect photo images having of dwellings are to be carried out, the first step would be to detect photo images having rectangular sh
rectangular shape etc. ape etc. The next The next step would step would be to rbe to recognize, say, ecognize, say, a single stora single storeyey construction and a double st
construction and a double storey constructionorey construction. . Delineation of the twDelineation of the two groups of objectso groups of objects would be done under the process of analysis in which, a boundary line may be drawn would be done under the process of analysis in which, a boundary line may be drawn separating the two groups.
separating the two groups. At this stage, in view of variouAt this stage, in view of various converging evidence, it mas converging evidence, it may bey be deduced that on
deduced that one group is a single store group is a single storey dwelling. ey dwelling. In more diffIn more difficult cases this would icult cases this would bebe done in the process of classification and a code number appointed to the groups to help done in the process of classification and a code number appointed to the groups to help field examin
field examinations. ations. Cartographic reCartographic representation presentation would be mawould be made under de under the process ofthe process of idealization.
idealization.
Convergence of evidence: Convergence of evidence:
Image interpretation is basically a deductive process. Features that can be Image interpretation is basically a deductive process. Features that can be recognized and identified directly lead the image interpreter to the identification and recognized and identified directly lead the image interpreter to the identification and location of other features. Even though all aspects of an area are irreversibly interwined, location of other features. Even though all aspects of an area are irreversibly interwined, the interpreter must begin some place, he can not consider drainage, landform, vegetation, the interpreter must begin some place, he can not consider drainage, landform, vegetation, and manmade f
and manmade features simultaneatures simultaneously. eously. He should begin wHe should begin with one featuith one feature or group ofre or group of features and th
features and then en on to the others, on to the others, integrating each ointegrating each of the facets of thf the facets of the terrain as hee terrain as he goes. For each terrain, the interpreter must find his own point of beginning and then goes. For each terrain, the interpreter must find his own point of beginning and then consider each of
consider each of the various aspectthe various aspects of the terrain s of the terrain in logical fashion. in logical fashion. Deductive imDeductive imageage interpretation
interpretation requires conrequires conscious or unconscious or unconscious consideratscious consideration of the eleion of the elements of imagements of image interpretation
interpretation listed earlier. listed earlier. The completenThe completeness and accuracy of ess and accuracy of image interprimage interpretation areetation are proportional to the interpreter's understanding of how and why images show shape, size, proportional to the interpreter's understanding of how and why images show shape, size, tone, shadow, pattern, and texture, while an understanding of site, association, and tone, shadow, pattern, and texture, while an understanding of site, association, and resolution strengthens the interpreter's ability to integrate the different features making resolution strengthens the interpreter's ability to integrate the different features making up
up a a terrain. terrain. For For the the beginners, beginners, systematic systematic consideration consideration of of the the elements elements of of imageimage interpretation should precede integrated terrain
The principle of convergence of evidence requires the interpreter first to recognize The principle of convergence of evidence requires the interpreter first to recognize basic features or types of features and then to consider their arrangement (pattern) in the basic features or types of features and then to consider their arrangement (pattern) in the a real
a real context. context. Several inSeveral interpretations terpretations may suggest may suggest themselves. themselves. Critical Critical examination examination ofof the evidence usually sho
the evidence usually shows that all interpretatiows that all interpretations but one are unlikely or imns but one are unlikely or impossible. possible. TheThe greatest difficulty in interpreting images involves judging degrees of
greatest difficulty in interpreting images involves judging degrees of probability.probability. Sensors in
Sensors in Photographic Image Interpretation Photographic Image Interpretation
As stated earlier, characteristics not visible to the human eye can also be recorded As stated earlier, characteristics not visible to the human eye can also be recorded and displayed by u
and displayed by using proper sensor tysing proper sensor types. pes. Digital data can also be tranDigital data can also be transferred onto anysferred onto any type of film, depen
type of film, depending on the type of study to be cading on the type of study to be carried out. rried out. Normally, the four tyNormally, the four types ofpes of films are used for visual data display as follows.
films are used for visual data display as follows. a)
a) Black-and-white Black-and-white panchromatic,panchromatic, b)
b) Black-and-white Black-and-white infraredinfrared c) Colour,
c) Colour, d)
d) Colour Colour infrared/fainfrared/false lse colourcolour
All of the above types are available in different grades and sensitivities that can be All of the above types are available in different grades and sensitivities that can be preselected for a particu
preselected for a particular use. lar use. An interpreter must know the chaAn interpreter must know the characteristics of each ofracteristics of each of these before start
these before starting an interpretaing an interpretation job. tion job. The same is truThe same is true for the digital de for the digital data displayata display for multispectral, thermal and radar imagery.
for multispectral, thermal and radar imagery.
METHODS OF ANALYSIS AND REFERENCE LEVELS METHODS OF ANALYSIS AND REFERENCE LEVELS
The mental process involved in image-interpretation is related to the reference The mental process involved in image-interpretation is related to the reference levels of the interpreter, i.e. the capacity of the interpreter to make decisions, consciously levels of the interpreter, i.e. the capacity of the interpreter to make decisions, consciously or unconsciously.
or unconsciously. The reference leveThe reference level in context is the amount of knowledl in context is the amount of knowledge stored in thege stored in the mind of any group of personnel involved in the interpretation of photographs or imagery. mind of any group of personnel involved in the interpretation of photographs or imagery. Methods of analysis depend on the type of material used for interpretation as well as the Methods of analysis depend on the type of material used for interpretation as well as the instruments and equ
instruments and equipment available. ipment available. The following methods are genThe following methods are generally used.erally used. Monocular analysis:
Monocular analysis: in in the the case of case of satellite imsatellite imagery agery and photand photographic eographic enlargementsnlargements Stereoscopic analysis
Stereoscopic analysis : : for for vertical/near vertical/near vertical vertical aerial aerial photographs, photographs, SPOT SPOT as as well well asas IRS-IC
IRS-IC stereo-imagerystereo-imagery.. Densitometric analysis
Densitometric analysis : for both aeri: for both aerial photographs and al photographs and imagery for imagery for quantitative aquantitative analysisnalysis using
using densitometedensitometers, rs, based based on on the measurement the measurement of of tonal variation, tonal variation, a a fundamentalfundamental characteristic
characteristic of of all all objects, objects, for for identifying identifying terrain terrain features. features. Such Such analysis analysis is is nownow carried out using digital image
carried out using digital image processing systems (refer DIP lectures).processing systems (refer DIP lectures). The Use of Multiple Images in
The Use of Multiple Images in Image InterpretatiImage Interpretation on
Advances in sensor and platform technology have increased the amount and type of Advances in sensor and platform technology have increased the amount and type of information available
information available to the image interpto the image interpreter. reter. Sensor systems currSensor systems currently being used areently being used are capable of presenting the interpreter with a visual representation of energy emitted, capable of presenting the interpreter with a visual representation of energy emitted, reflected and transmitted at wavelengths outside the visible portion of
spectrum and th
spectrum and therefore beyonerefore beyond direct visual expd direct visual experience. erience. Available sensor platfoAvailable sensor platforms canrms can present the
present the interpreter interpreter with a variewith a variety of scales. ty of scales. The impact The impact of these of these technologicaltechnological advances has been to present the interpreter with a multiplicity of data for interpretation. advances has been to present the interpreter with a multiplicity of data for interpretation. These are the use of multi-band, multi-date, multi-stage, and multi-disciplinary analysis These are the use of multi-band, multi-date, multi-stage, and multi-disciplinary analysis techniques.
techniques.
Multi-band concept and images Multi-band concept and images
Basic to the interpretati
Basic to the interpretation of multiple images is what haon of multiple images is what has come to be known s come to be known as theas the multi-band concept.
multi-band concept. The level of energy rThe level of energy reflected, emitteeflected, emitted and transmitted d and transmitted by objectsby objects normally varie
normally varies with ws with wavelength throuavelength throughout the ghout the electromagnetic electromagnetic (EM) spectru(EM) spectrum. m. TheThe signature of an object on an image is governed by the amount of energy received by the signature of an object on an image is governed by the amount of energy received by the sensor within the wa
sensor within the wavelength range in which thvelength range in which that sensor images. at sensor images. Therefore, a uTherefore, a unique tonalnique tonal signature for a particular object can often be identified if the energy that is
signature for a particular object can often be identified if the energy that is being emitted,being emitted, reflected, and/or transmitted from it, is broken down into carefully selected wavelength reflected, and/or transmitted from it, is broken down into carefully selected wavelength bands.
bands. Stated another Stated another way, conventioway, conventional imaging systems nal imaging systems sensitive to brsensitive to broad wavelengthoad wavelength regions within the EM spectrum, e.g., colour film in a conventional aerial camera, may not be regions within the EM spectrum, e.g., colour film in a conventional aerial camera, may not be as effective in producing adequate object-to-background contrast ratios as imagery as effective in producing adequate object-to-background contrast ratios as imagery obtained from a number of
obtained from a number of selected narrow-wavelengtselected narrow-wavelength bands.h bands.
The term multiband is often applied to the analysis and/or acquisition of imagery The term multiband is often applied to the analysis and/or acquisition of imagery from within a particular wavelength band of the electromagnetic spectrum, e.g. visible, from within a particular wavelength band of the electromagnetic spectrum, e.g. visible, ultraviolet
ultraviolet or thermor thermal infraral infrared. ed. The teThe term rm multispectral multispectral image analyimage analysis sis is commonly is commonly used toused to denote the analysis of imagery from more than one spectral region, so it follows that the denote the analysis of imagery from more than one spectral region, so it follows that the combined analysis of images acquired in the ultraviolet, thermal infrared and/or microwave combined analysis of images acquired in the ultraviolet, thermal infrared and/or microwave regions would also increase the amount of information which could be extracted by the regions would also increase the amount of information which could be extracted by the interpreter.
interpreter. It is importaIt is important then for the nt then for the image interprimage interpreter to become eter to become aware of theaware of the important imaging characteristics of a variety of
important imaging characteristics of a variety of sensor systems.sensor systems. Multi
Multi date co- - date concepncept and imagt and imagery ery
Just as the recording of data in various bands of the spectrum can provide valuable Just as the recording of data in various bands of the spectrum can provide valuable information to the image interpreter, so too, in many cases, can the recording of energy information to the image interpreter, so too, in many cases, can the recording of energy from the same area through time prove valuable (multi-date or sequential photos/imagery). from the same area through time prove valuable (multi-date or sequential photos/imagery). Many features e
Many features exhibit unique xhibit unique changes with the passage changes with the passage of time. of time. It may be difficuIt may be difficult evenlt even with the use of multi-band, multi-spectral imagery acquired on a single date to discriminate with the use of multi-band, multi-spectral imagery acquired on a single date to discriminate and identify the mi
and identify the mix of agricultural crx of agricultural crops growing in a particops growing in a particular area. ular area. If multiple imaIf multiple imagege acquisition missions are coupled with a knowledge of the crop phonological cycles (crop acquisition missions are coupled with a knowledge of the crop phonological cycles (crop calendar) of the area unde
calendar) of the area under investigation, ider investigation, identification is facilitatedntification is facilitated. . This is true becauseThis is true because crops grown in an area generally will exhibit unique growth characteristics which, if known, crops grown in an area generally will exhibit unique growth characteristics which, if known, can aid in identification
can aid in identification. . Changes in urban areas, assessChanges in urban areas, assessment of flood or disaster ement of flood or disaster evaluation,valuation, and monitoring changes in coastal morphology are examples of studies in which the and monitoring changes in coastal morphology are examples of studies in which the inter-pretation of multi-date imagery can
Multi-stage concept and data Multi-stage concept and data
In a multistage sampling scheme, progressively more detailed information is In a multistage sampling scheme, progressively more detailed information is obtained for sma
obtained for smaller sub-samples of thller sub-samples of the area under investe area under investigation. igation. Basically, this methodBasically, this method takes advantages of increasingly finer resolution, which can be provided by the use of takes advantages of increasingly finer resolution, which can be provided by the use of either multiple sensor platforms (such a low and high-altitude aircraft and spacecraft) or by either multiple sensor platforms (such a low and high-altitude aircraft and spacecraft) or by using a variety of focal lengths from a single sensor platform. These act as sub-samples using a variety of focal lengths from a single sensor platform. These act as sub-samples which can be used to increase the efficiency of the sample selection in each subsequent which can be used to increase the efficiency of the sample selection in each subsequent stage.
stage. The precision The precision of the estimatof the estimated information ed information depends solely on depends solely on the relationshipsthe relationships between predictions made by image interpretation and the value of measured between predictions made by image interpretation and the value of measured characteristics of the
characteristics of the sample units used to estisample units used to estimate population parmate population parameters. ameters. It should beIt should be stressed here that the accuracy of the final estimate therefore depends solely on the stressed here that the accuracy of the final estimate therefore depends solely on the quality of image inte
quality of image interpretation at all levels of generpretation at all levels of generalization. ralization. The methodology is easy The methodology is easy toto employ.
employ. Operationally, the teOperationally, the technique is efficienchnique is efficient and provides for a greater t and provides for a greater portion of theportion of the work to be concentrated an areas of higher values.
work to be concentrated an areas of higher values.
- - Multi
Multi discidisciplinaplinary anary analysis lysis
It has been stated that remotely sensed data are "once written, many times read." It has been stated that remotely sensed data are "once written, many times read." Basically, this means that one image can be looked at by a number of specialists and each Basically, this means that one image can be looked at by a number of specialists and each may gain information of value to hi
may gain information of value to his or her particular discipline. s or her particular discipline. In order to ascertain theIn order to ascertain the agricultural potential of a given area, a team of geologists, hydrologists, pedologists, agricultural potential of a given area, a team of geologists, hydrologists, pedologists, agronomists, meteorologists, geographers, foresters and economists, among others, might agronomists, meteorologists, geographers, foresters and economists, among others, might examine the imagery of a given area. Having interpreted by various discipline specialists , a examine the imagery of a given area. Having interpreted by various discipline specialists , a synergistic
synergistic effect effect can be can be created. created. For For many tymany types of pes of earth-resourearth-resource analysis, ce analysis, the use the use ofof the convergence system by image interpretation of varying background is
the convergence system by image interpretation of varying background is likely to produce alikely to produce a more accurate and thorough analysis than could be achieved by a single image interpreter more accurate and thorough analysis than could be achieved by a single image interpreter working alone.
working alone.
INSTRUMENTS FOR
INSTRUMENTS FOR VISUAL INTERPRETATION VISUAL INTERPRETATION AND TRANSFER AND TRANSFER OF DATAOF DATA
Interpretation Instruments Interpretation Instruments
Monocular instruments: magnifiers Monocular instruments: magnifiers
Stereoscopic instruments: mirror and pocket
Stereoscopic instruments: mirror and pocket stereoscopestereoscope interpretoscope interpretoscope zoom stereoscope zoom stereoscope scanning mirror scanning mirror stereoscope stereoscope Instruments
Instruments for for Transfer Transfer of Dataof Data For
For flat flat terrain: terrain: SketchmasterSketchmaster
Stereosketchmaster Stereosketchmaster Zoom transferscope Zoom transferscope
Optical pantograph or reflecting projector Optical pantograph or reflecting projector
For
For hilly hilly terrain: terrain: StereoplottersStereoplotters
Orthophoto together with its stereo-mate, can be used Orthophoto together with its stereo-mate, can be used forfor interpretatio
interpretation and n and delineation’s. Sidelineation’s. Since preparation ofnce preparation of orthophoto and its stereo-mate is a
orthophoto and its stereo-mate is a complex process, thecomplex process, the method is not so popular.
method is not so popular. Conclusion
Conclusion
The scope of image-interpretation as a tool for analysis and data collection is The scope of image-interpretation as a tool for analysis and data collection is widening with the advance of remote sensing techniques. Space images have already found widening with the advance of remote sensing techniques. Space images have already found their use i
their use in interpren interpretation for tation for the earth the earth sciences. sciences. Because of Because of the flexibility the flexibility of itsof its techniques and substantial gains in accuracy, speed and economy over conventional ground techniques and substantial gains in accuracy, speed and economy over conventional ground methods, th
methods, the future e future of image-intof image-interpretation erpretation is assured. is assured. However, grHowever, great endeaveat endeavor isor is required on the part of the interpreter to assess his or her own empirical knowledge in required on the part of the interpreter to assess his or her own empirical knowledge in order to for
order to formulate the optimulate the optimum data rmum data requirements fequirements for differenor different disciplines. t disciplines. This isThis is essential for the better development of
essential for the better development of image-interprimage-interpretation and for widening the etation and for widening the scope ofscope of application of its techniques.
