n o m r a H a i r o t c i V Michael Shapiro y r o t a r o b a L h c r a e s e R g n i r e e n i g n E n o i t c u r t s n o C y m r A . S . U ABSTRACT e h t g n i s u e r u d e c o r p p e t s y b p e t s a h g u o r h t r e d a e r e h t s e d i u g l a i r o t u t s i h T
imagery commands available in the Geographic Resource Analysis Support System a n i s m a r g o r p g n i s s e c o r p -e g a m i S S A R G e h t s e b i r c s e d e r u d e c o r p e h T . ) S S A R G (
sequence that is often used in image processing, starting with loading imagery data , r a e n i l e r o f e r e h t s i e r u d e c o r p e h T . t i g n i y f i t c e r d n a , a t a d e h t g n i y f i s s a l c , S S A R G o t n i
but does branch occasionally to describe alternate directions when alternate paths are n o i t a n i g a m i r e h r o s i h e s u o t d e g a r u o c n e s i r e d a e r e h t l a i r o t u t e h t g n i r u D . e l b a l i a v a
and knowledge of GRASS to identify non-imagery GRASS programs that may be . s p a m d e fi i s s a l c r o y r e g a m i l a t i g i d w a r o t d e i l p p a
1. INTRODUCTION ... 2 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S D N A M M O C Y R E G A M I E H T . 2
3. DESCRIPTIONS OF THE IMAGERY COMMANDS ... 3 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ? Y R E G A M I L A T I G I D S I T A H W . 4
5. THE IMAGERY LOCATION ... 4 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N O I T A C O L e t a n i d r o o C Y , X n a g n i t a e r C . 1 . 5
5.2. Sample X,Y Default Region ... 6 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S K S A M D N A S N O I G E R . 6 7. TAPE EXTRACTION ... 7 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . e p a T m o r F y r e g a m I S S M g n i t c a r t x E . 1 . 7
7.2. Extracting TM Imagery From Tape ... 12 6 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . e p a T m o r F y r e g a m I l a t i g i D f o s e p y T r e h t O g n i t c a r t x E . 3 . 7
8. THE CONTRAST STRETCH ... 23 3 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E T I S O P M O C R O L O C E H T . 9 10. IMAGERY GROUPS ... 25 0 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S P U O R G Y R E G A M I G N I T E G R A T . 1 1 12. IMAGE CLASSIFICATION ... 31 2 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . r e t s u l c . i . 1 . 2 1 12.2. i.maxlik ... 34 6 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N O I T A C I F I T C E R E G A M I . 3 1 13.1. i.points ... 37 2 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . y f i t c e r . i . 2 . 3 1
14. A NOTE ABOUT PROGRAM SEQUENCE ... 43 3 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S E G A M I G N I H C T A P . 5 1
15.1. Patching and the Image-Processing Sequence ... 43 5 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . s e l i F l l e C d e fi i t c e r n U g n i h c t a P . 2 . 5 1
N O I T C U D O R T N I . 1
Within the last decade geographic information systems (GIS) and image-processing systems have -o l o n h c e t o w t e s e h t t a h t e r i u q e r e r u t u f e h t f o s e g n e l l a h c e h T . t n e m p o l e v e d y r a n o i t u l o v e n a e n o g r e d n u
gies be integrated. The Geographic Resource Analysis Support System (GRASS) integrates these two . w o l e b d e b i r c s e d e r a s e g a t n a v d a e s e h t f o e m o S . s e g a t n a v d a s u o r e m u n n i g n i t l u s e r s e i g o l o n h c e t
A GIS has four components: a data input system, a data storage and retrieval system, a data d n a l a i t a p s e d u l c n i s t u p n i a t a d e h T . m e t s y s g n i t r o p e r a t a d a d n a , m e t s y s s i s y l a n a d n a n o i t a l u p i n a m
thematic data derived from a combination of existing maps, aerial photographs, and manual interpreta-e c n a t s i d e m o s t a d e r i u q c a y r e g a m i s i y r e g a m i d e s n e s y l e t o m e R . y r e g a m i d e s n e s y l e t o m e r f o s n o i t
using a camera or a sensor. With a GIS an analyst can define spatial procedures to generate new infor -b o r p A . r e b m i t t s e v r a h r o , t a t i b a h e f i l d l i w a e v r e s e r p , d a o r a d l i u b o t n o i t a c o l t s e b e h t s a h c u s , n o i t a m
lem exists, however, in that the input data on which a GIS is based become obsolete quickly. Remote n i n o i t a m r o f n i c i t a m e h t d n a l a i t a p s e h t e t a d p u o t s n a e m e v i t c e ff e -t s o c d n a l a i t n e s s e n a e r a a t a d g n i s n e s
a GIS. Remote sensing products are also valuable in themselves, as a cost effective source of geo-, n o i t a c o l e r u t a e f l a c i g o l o e a h c r a , y t i v i t c u d o r p n o i t a t e g e v , e p y t n o i t a t e g e v s a h c u s n o i t a m r o f n i c i h p a r g
water quality, and land use change.
An image-processing system has at least five elements: image input, image storage, image : s m e t s y s o w t e s e h t f o y t i r a l i m i s e h t e t o N . g n i t r o p e r n o i t a m r o f n i d n a , t n e m s s e s s a y c a r u c c a , s i s y l a n a ________________________________ G N I S S E C O R P E G A M I S I G ________________________________ t u p n i t u p n i storage storage s i s y l a n a s i s y l a n a accuracy assessment g n i t r o p e r g n i t r o p e r ________________________________ -r e t s a r a s i S I G e h t f I . m e t s y s h c a e r o f s n o i t c n u f t n e r e ff i d e r i u q e r s t n e m e l e s i s y l a n a d n a t u p n i e h t y l n O
based system, the storage and reporting functions are identical. Some of the analysis functions may -u o r s i s y l a n a S I G d r a d n a t s y l l a u t c a e r a s m a r g o r p t n e m s s e s s a y c a r u c c a e g a m i e h t , e l p m a x e r o F . p a l r e v o
tines. It seems natural then, that these two systems should be integrated.
n a c y l n o t o n , d e t a r g e t n i e r a s m e t s y s g n i s s e c o r p -e g a m i d n a s m e t s y s n o i t a m r o f n i c i h p a r g o e g n e h W
the remote sensing data be used to update the GIS, but the GIS thematic data and attributes can be used e h t s r e ff o S S A R G , s e i t i l i b a p a c g n i s s e c o r p -e g a m i d n a S I G g n i t a r g e t n i y B . n o i t a c fi i s s a l c e g a m i e d i u g o t
analyst these advantages.
This tutorial guides the reader through a step-by-step procedure using the imagery commands s i t I . d e b i r c s e d o s l a e r a s d n a m m o c S S A R G y r e g a m i -n o n , e l b a c i l p p a e r e h W . 0 . 4 S S A R G n i e l b a l i a v a
assumed that the reader has a knowledge of the basic concepts of GRASS such as its raster (grid cell) r e f e r , s t p e c n o c e s e h t f o n o i t p i r c s e d a r o F . s n o i g e r d n a , T E S P A M , N O I T A C O L , s r e y a l p a m s t i , t a m r o f to An Introduction to GRASS. S D N A M M O C Y R E G A M I E H T . 2
All of the GRASS 4.0 imagery commands begin with a lower case i followed by a dot. These s i s i h t t u b , g n i s s e c o r p e g a m i n i d e s u n e t f o s i t a h t e c n e u q e s a n i l a i r o t u t s i h t n i d e t n e s e r p e r a s m a r g o r p
not the only order in which they can be executed. Please refer to section 14, A NOTE ABOUT PRO-d e b i r c s e d e r a s d n a m m o c y r e g a m i e h T . S E G A M I G N I H C T A P , 5 1 n o i t c e s d n a , E C N E U Q E S M A R G
in this tutorial in the following sections. n o i t c a r t x E e p a T . 7 n o i t c e S i.tape.mss.h s s m . e p a t . i i.tape.tm r e h t o . e p a t . i
h c t e r t S t s a r t n o C e h T . 8 n o i t c e S i.grey.scale e t i s o p m o C r o l o C e h T . 9 n o i t c e S i.composite s p u o r G y r e g a m I . 0 1 n o i t c e S i.group
Section 11. Targeting Imagery Groups t e g r a t . i
Section 12. Image Classification r e t s u l c . i i.maxlik
Section 13. Image Rectification s t n i o p . i i.rectify
3. DESCRIPTIONS OF THE IMAGERY COMMANDS
o s l a e r a s n o i t p i r c s e d e s e h T . d e d i v o r p s i d n a m m o c y r e g a m i h c a e f o n o i t p i r c s e d f e i r b a , w o l e B
available by running the command g.manual from within GRASS. Typing the word g.manual will l l A . t u o t i t n i r p o t n o i t p o e h t r e s u e h t e v i g d n a m a r g o r p S S A R G y n a r o f y r t n e l a u n a m e h t y a l p s i d
GRASS programs mentioned in this tutorial, other than the imagery programs, are referenced with their . n o i g e r . g , e l p m a x e r o f , s t e k c a r b n i n o i t c e s y r t n e l a u n a m IMAGERY DESCRIPTION N O I T C N U F
i.cluster – An imagery function that generates spectral signatures for land-cover types in an r o f t u p n i s a d e s u s i e l fi e r u t a n g i s g n i t l u s e r e h T . m h t i r o g l a g n i r e t s u l c a g n i s u e g a m i i.maxlik.
i.composite – An imagery function that creates a color composite image from 3 band files specified . r e s u e h t y b
i.colors – An imagery function that creates colors for imagery groups. This program is not yet e c a l p e r l l i w t i d e t e l p m o c s i t i n e h W . l a i r o t u t s i h t n i d e r e v o c t o n s i d n a e t e l p m o c
i.composite and the color option in i.group.
o t e l b a t r o l o c e l a c s y e r g h c t e r t s t s a r t n o c m a r g o t s i h a s n g i s s a t a h t n o i t c n u f y r e g a m i n A – e l a c s . y e r g . i a map layer.
i.group – An imagery function that creates and edits groups and subgroups of imagery files. a t a d y r e g a m i n i s e c n a t c e fl e r l a r t c e p s l e x i p e h t s e fi i s s a l c t a h t n o i t c n u f y r e g a m i n A – k i l x a m . i
based on the spectral signature information generated in i.cluster.
n a n o s t n i o p m e t s y s e t a n i d r o o c k r a m o t r e s u e h t s e l b a n e t a h t n o i t c n u f y r e g a m i n A – s t n i o p . i
image to be rectified and then input the coordinates of each point for creation of a S S A R G e h t r o f t u p n i s a d e d e e n s i x i r t a m n o i t a m r o f s n a r t e h T . x i r t a m n o i t a m r o f s n a r t program i.rectify.
i.rectify – An imagery function that rectifies an image by computing a coordinate transformation e h t y b d e t a e r c x i r t a m t n e i c ffi e o c n o i t a m r o f s n a r t e h t g n i s u e g a m i e h t n i l e x i p h c a e r o f
GRASS program i.points.
i.tape.mss – An imagery function that extracts Multispectral Scanner Imagery from half-inch tape. l a r t c e p s i t l u M t a s d n a L m o r f n o i t a m r o f n i r e d a e h s t c a r t x e t a h t n o i t c n u f y r e g a m i n A – h . s s m . e p a t . i
Scanner imagery data stored on half-inch tape.
T O P S d n a ) . c t e , P A H N ( y r e g a m i l a i r e a d e n n a c s s t c a r t x e t a h t n o i t c n u f y r e g a m i n A – r e h t o . e p a t . i
imagery from half-inch tape.
i.tape.tm – An imagery function that extracts Thematic Mapper imagery from half-inch tape. y r e g a m i n a r o f N O I T A C O L t e g r a t S S A R G a s e h s i l b a t s e t a h t n o i t c n u f y r e g a m i n A – t e g r a t . i group. ? Y R E G A M I L A T I G I D S I T A H W . 4
To perform digital image processing of remotely sensed imagery the imagery must be in a digital o t d e t r e v n o c e b n a c ) h p a r g o t o h p l a i r e a n a s a h c u s ( t a m r o f g o l a n a n i y l l a i t i n i s i t a h t y r e g a m I . t a m r o f
digital format in a digitization process called optical-mechanical scanning. Film density of the blue, the r o f 5 5 2 o t 0 m o r f s e g n a r t a h t ) N D ( r e b m u n l a t i g i d a o t d e t r e v n o c s i s r e y a l n o i s l u m e d e r e h t d n a , n e e r g
the chosen sampling interval.1 The DN value 0 can be assigned to represent the lack of reflected or emitted electromagnetic radiation and the value 255 to represent maximum reflectance. An example of e u l b e h t r o f e n o : s d n a b e e r h t s a h e g a m i l a t i g i d g n i t l u s e r e h T . s r e t e m o r c i m 0 0 1 s i l a v r e t n i g n i l p m a s a
emulsion layer, one for the green emulsion layer, and one for the red emulsion layer. The sampling s i t a m r o f r e t s a R . t a m r o f r e t s a r n i d e r o t s s i h c i h w e g a m i l a t i g i d e h t n i l e x i p t i b -8 e n o s e m o c e b l a v r e t n i
a two-dimensional matrix composed of cells in which each cell has the DN integer value. The DNs of d e t c e fl e r s i t a h t e c n a i d a r e v i t a l e r e h t e t a m i x o r p p a y l e s o l c ) y t i s n e d m l fi g n i t n e s e r p e r ( e g a m i l a t i g i d e h t
and emitted from the features on the ground within the sampling interval.
e v i t i s o p a i d e h t f o e l a c s e h t d n a l a v r e t n i g n i l p m a s e h t f o n o i t c n u f a s i e g a m i e h t f o n o i t u l o s e r e h T
being scanned. If the sampling interval is 100 micrometers and the scale of the aerial photo is : s r e t e m 5 s i n o i t u l o s e r e h t n e h t , 0 0 0 , 0 5 : 1 100 micrometers * 50000 = 5 meters . d e t c e l l o c e r a y e h t s a t a m r o f l a t i g i d n i y l t c e r i d d e r o t s e r a y r e g a m i d e s n e s y l e t o m e r f o s e p y t r e h t O
The storage medium is usually half-inch magnetic tape in raster format. (Video imagery is also stored s d n a m m o c y r e g a m i o n e r a e r e h t t n e s e r p t A . t a m r o f o e d i v l a i c e p s a n i d e r o t s s i t i t u b , e p a t h c n i -f l a h n o
in GRASS to read video data stored on video tape.) Examples of these other types of remotely sensed -s y S d n a , ) M T ( a t a d r e p p a M c i t a m e h T t a s d n a L , ) S S M ( a t a d r e n n a c S l a r t c e p s i t l u M t a s d n a L : e r a y r e g a m i
tems Probatoir d’Observation de la Terre data (SPOT), to name a few. Each of these types of data are e h t , r o s n e s e h t f o t c u d o r p a s i t a h t e g a r e v o c f o a e r a n a d n a n o i t u l o s e r c fi i c e p s a s a h h c a E . a t a d e t i l l e t a s
height of the sensor above the earth, and the focal length. Like aerial imagery, the digital numbers for n o s e r u t a e f m o r f n o i t a i d a r d e t t i m e d n a d e t c e fl e r e h t t n e s e r p e r d n a 5 5 2 o t 0 m o r f e g n a r o s l a a t a d e s e h t the ground.
The imagery programs in GRASS are able to read and analyze both digitized aerial imagery and s i y r e g a m i l a t i g i d f o s e p y t e s e h t g n i z y l a n a d n a g n i d a e r r o f e c n e u q e s m a r g o r p e h T . a t a d e t i l l e t a s
described in the following sections. N O I T A C O L Y R E G A M I E H T . 5
To use the imagery programs, GRASS 4.0 must be invoked by typing: 0 . 4 s s a r g _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Imagery data is usually 0 to 255 but GRASS is not restricted to this data range.
After typing this command and hitting <RETURN>, a screen is displayed that requires you to . T E S P A M d n a N O I T A C O L S S A R G a e s o o h c
Before choosing a LOCATION in which to extract imagery, it is important to realize that raw -i d r o o c M T U a s a h c u s m e t s y s e t a n i d r o o c d r a d n a t s a h t i w d e c n e r e f e r -o e g t o n s i e p a t n o y r e g a m i l a t i g i d
nate system or a State Plane coordinate system when it is captured or digitized. The imagery on tape is e p a t e g a m i r o f , e r o f e r e h T . d e r o t s s i t i h c i h w n i t a m r o f e h t f o s n m u l o c d n a s w o r e h t g n i s u d e c n e r e f e r
extraction, a GRASS LOCATION must be chosen that has an x,y (row, column) coordinate system. e s o o h c n a c u o Y . y r e g a m i d e m a n N O I T A C O L e t a n i d r o o c y , x n a h t i w s e m o c S S A R G f o n o i s r e v 0 . 4 e h T
this LOCATION for imagery extraction, or you can create your own x,y coordinate LOCATION. You r o / d n a , t c a r t x e u o y t a h t s e g a m i f o n o i t c e l l o c r o e g a m i y r e v e r o f N O I T A C O L y , x n a e t a e r c o t t n a w y a m
you may want to use the x,y LOCATION, imagery, for general imagery tape extraction.
f o l l A . m e t s y s e t a n i d r o o c y , x n a h t i w N O I T A C O L a n i n u r e b t s u m s d n a m m o c e p a t . i e h t y l n O : e t o N
the other GRASS imagery commands can be run in a LOCATION having any GRASS coordinate sys-.
m e t
5.1. Creating an X,Y Coordinate LOCATION
The procedure to create a LOCATION with an x,y coordinate system in GRASS is the same as l a i c e p s t i r e m t a h t s e c n e r e ff i d w e f a e r a e r e h t , r e v e w o h , S S A R G n i N O I T A C O L y n a g n i t a e r c r o f t a h t attention.
The first step is the same for any LOCATION: enter the new LOCATION name and respond g n i d a e r e l i h W ( . N O I T A C O L w e n a e t a e r c o t e k i l d l u o w u o y r e h t e h w f o n o i t s e u q e h t o t y l e v i t a m r ffi a
this tutorial, you may want to follow along, implementing some of the commands, using imagery of , N O I T A C O L e t a n i d r o o c M T U e h t n i e d i s e r y l l a u t n e v e l l i w t a h t , e l b a l i a v a f i , a t o k a D h t u o S , h s fi r a e p S
spearfish. spearfish is the sample database for GRASS. Therefore, for demonstration purposes, we ) . y x _ r a e p s N O I T A C O L y , x w e n e h t e m a n l l i w
In the second step, you will be asked whether you have the information to create a new LOCA-l l i w u o y , N O I T A C O L e n a l P e t a t S r o M T U a g n i t a e r c e k i l n U . o o t n o i t s e u q s i h t o t s e y r e w s n A . N O I T
not need to have available information from maps or other reference materials. : N O I T A C O L e h t r o f m e t s y s e t a n i d r o o c e h t y f i c e p s o t d e k s a e b l l i w u o y , t x e N
Please enter the following coordinate system information for
> y x _ r a e p s < n o i t a c o l 0 x,y 1 UTM 2 State Plane >
The code number for an x,y coordinate system in GRASS is 0. The code number for the UTM coordi-, 0 r e t n E . 2 s i m e t s y s e t a n i d r o o c e n a l P e t a t S e h t r o f r e b m u n e d o c e h t d n a , 1 s i S S A R G n i m e t s y s e t a n
. m e t s y s e t a n i d r o o c y , x e h t r o f
Then, the following screen will be displayed:
Please enter the following information for location<spear_xy> : E L T I T DEFAULT REGION _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _________________________________________________ _ NORTH EDGE:0.00 E G D E T S A E E G D E T S E W 0.00 0.00 0 0 . 0 : E G D E H T U O S _________________________________________________ _________________________________________________ N O I T U L O S E R D I R G East-West:0.00 North-South:0.00 E U N I T N O C O T > C S E < T I H S R E W S N A L L A G N I T E L P M O C R E T F A (OR<Ctrl-C> TO CANCEL) -p a m e h t , 0 . 4 S S A R G n i N O I T A C O L e t a n i d r o o c y , x n a o t n i e p a t m o r f d e t c a r t x e e r a a t a d y r e g a m i n e h W
set region setting will be changed to match the extracted rows and columns from the tape. The initial , N O I T A C O L y , x e h t r o f n o i g e r t l u a f e d a s a t p e c x e , e c n a c fi i n g i s e l t t i l f o e r a , n e h t , s e t a n i d r o o c p u -t r a t s
which is a requirement for every LOCATION in GRASS. Any general coordinates, then, may be : s a g n o l s a , n o i g e r t l u a f e d e h t s a d e r e t n e
1 The north and south coordinates are negative;
t s r fi n e s o h c e h t n a h t s s e l 5 . 0 s i e g d e n r e h t r o n e h t : 5 . y b t e s ff o e r a s e t a n i d r o o c e h t f o l l A 2
row, the southern edge is 0.5 greater than the chosen last row, the west edge is 0.5 less than ; n m u l o c t s a l n e s o h c e h t n a h t r e g r a l 5 . 0 s i e g d e t s a e e h t d n a , n m u l o c t s r fi n e s o h c e h t
3 The north coordinate is greater than the south coordinate; and . t s e w e h t n a h t r e t a e r g s i e t a n i d r o o c t s a e e h T 4
The reason the north and south coordinates are negative is because GRASS requires that the o t h t r o n m o r f e s a e r c n i e p a t e h t n o s e t a n i d r o o c w o r e h t t u b h t u o s o t h t r o n m o r f e s a e r c e d s e u l a v n o i g e r
south. Assigning negative values to the rows allows them to decrease from north to south and, by . d e t r o p e r e r a s r e b m u n w o r t c e r r o c e h t , s n g i s s u n i m e h t g n i r o n g i
By setting the northern edge to 0.5 less than the first row, the southern edge to 0.5 larger than the t s a l e h t n a h t r e g r a l 5 . 0 o t e g d e t s a e e h t d n a , n m u l o c t s r fi e h t n a h t s s e l 5 . 0 o t e g d e t s e w e h t , w o r t s a l
column, the x,y coordinates (as integers 1 to n) become located at the center of the pixel and are then . e p a t e h t n o s r e b m u n n m u l o c d n a w o r e h t s a e m a s e h t
: e b d l u o w n o i g e r t l u a f e d e t a n i d r o o c y , x d i l a v a f o e l p m a x e n A DEFAULT REGION _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ___________________________________________________ _ NORTH EDGE:-0.50 E G D E T S A E E G D E T S E W 0.50 1000.50 0 5 . 0 0 0 1 -: E G D E H T U O S ___________________________________________________ ___________________________________________________ N O I T U L O S E R D I R G East-West:1.00 North-South:1.00 E U N I T N O C O T > C S E < T I H S R E W S N A L L A G N I T E L P M O C R E T F A (OR<Ctrl-C> TO CANCEL) . N O I T A C O L y , x y n a e t a e r c o t d e s u e b n a c s e t a n i d r o o c e s e h T
6. REGIONS AND MASKS
All of the tape extraction programs (i.tape.mss, i.tape.tm, and i.tape.other) set the mapset region e r o m f I . e p a t e h t m o r f d e t c a r t x e g n i e b t e s b u s e g a m i r o e g a m i e h t f o s e t a n i d r o o c n m u l o c d n a w o r e h t o t
than one image or image subset is extracted into the same x,y LOCATION, and the images or image y a l p s i d o t , n e h t , ) s n m u l o c d n a s w o r d e t c a r t x e e h t n o d e s a b e r a h c i h w ( s n o i g e r t n e r e ff i d e v a h s t e s b u s
one of the image raster files in the x,y LOCATION, you will have to check the current MAPSET region -o r p S S A R G e h t e s u o t s i s i h t o d o t y a w A . d e y a l p s i d e b o t e l fi r e t s a r e h t s e h c t a m t i t a h t e r u s e k a m o t
gram g.region to see the current region setting, and to modify the current region setting. Use the . g n i t t e s n o i g e r t n e r r u c e h t y f i d o m o t d n a , g n i t t e s n o i g e r t n e r r u c e h t e e s o t n o i g e r . g m a r g o r p S S A R G
The presence of a mask in an x,y LOCATION also requires special attention. If a mask is set to e g a m i t n e r e ff i d a y a l p s i d o t s e h s i w r e s u e h t d n a N O I T A C O L y , x n a n i e g a m i e n o f o e l fi r e t s a r d n a b a
or band raster file in the same LOCATION, then the mask will effect the displayed raster file as well, f o y a l p s i d e h t e b y a m t l u s e r e h T . y a l p s i d o t h s i w u o y e l fi r e t s a r e h t o t t e s s i n o i g e r t e s p a m e h t f i n e v e
a raster file composed of zeros. To avoid this problem, check to see if there is a mask by typing . s l i a t e d r e h t r u f r o f k s a m . r r o f y r t n e l a u n a m e h t e e S . k s a m . r 7. TAPE EXTRACTION
To load or read digital imagery into GRASS, four commands are available: h . s s m . e p a t . i i.tape.mss m t . e p a t . i i.tape.other
If the image is an MSS image the command i.tape.mss.h can be used to read the header on the m o r f e g a m i S S M n a f o n o i t r o p a r o e g a m i S S M n a t c a r t x e o t d e s u s i s s m . e p a t . i d n a m m o c e h T . e p a t
tape. If the image is a TM image, the command i.tape.tm is used to extract the image. If the image is d e r o t s e p y t y r e g a m i r e h t o e m o s r o , e g a m i T O P S , e g a m i P P A N , e g a m i P A H N , e g a m i l a i r e a d e n n a c s a
on half-inch tape (except for video format), the program i.tape.other is used to extract the data from . s m a r g o r p e s e h t f o h c a e e s u o t w o h s n i a l p x e n o i t c e s s i h T . e p a t
7.1. Extracting MSS Imagery From Tape
extrac-. n o i t 7.1.1. i.tape.mss.h
This program is an imagery function that extracts header information from Landsat Multispectral e h t r o f e d u t i g n o l d n a e d u t i t a l r e t n e c e h t s n i a t n o c r e d a e h e h T . e p a t h c n i f l a h n o d e r o t s y r e g a m i r e n n a c S
image and the number of rows and columns in the scene. This information may be of use in locating r a i l i m a f t o n e r a u o y f I . d e r i u q e r t o n s i e g a m i e l o h w e h t f i , t s e r e t n i f o e g a m i S S M e h t f o n o i t r o p e h t
with MSS imagery, however, the header information format may be difficult to understand. This pro-. s s m . e p a t . i g n i n n u r o t r o i r p d e r i u q e r t o n s i m a r g
To run the program, first mount the tape on the tape drive for the machine you are using and, at : e p y t , t p m o r p S S A R G e h t 2 e m a n _ e v i r d _ e p a t h . s s m . e p a t . i
The tape drive name will depend on the system being used but it is sometimes of the form /dev/rmt0. : e m o c e b n e h t d l u o w d n a m m o c s i h t , o s f I i.tape.mss.h /dev/rmt0 e h t d a e r o T . n e e r c s e h t n o d e y a l p s i d e b l l i w n o i t a m r o f n i r e d a e h e p a t e h t , s i h t e k i l d e r e t n e f I
header information into a file (thereby saving it for future use), the output can be redirected using the : d n a m m o c
i.tape.mss.h /dev/rmt0>headerfile
. e p a t e h t n o s r u c c o t a h t n o i t a m r o f n i r e d a e h e h t n i a t n o c l l i w e l fi r e d a e h d e fi i c e p s -r e s u e h T 7.1.2. i.tape.mss
This program is an imagery function that extracts Multispectral Scanner (MSS) Imagery from half . e p a t h c n i
Note: This program must be run in a LOCATION with an x,y coordinate system (see section 5, THE . ) N O I T A C O L Y R E G A M I
Before running a tape extraction, it is a good idea to check to see if there is enough disk space in e b n a c e g a m i S S M n a n i s e t y b f o r e b m u n e h T . e n i h c a m r u o y n o d e t c a r t x e e b o t s e l fi e h t e r o t s o t h c i h w
calculated by multiplying the number of rows in the image by the number of columns in the image and s w o r f o r e b m u n e h t g n i n i m r e t e D . d e t c a r t x e e b o t s d n a b f o r e b m u n e h t y b r e b m u n t a h t g n i y l p i t l u m n e h t
and columns in an image is explained in subsection 7.1.2.2., Row and Column Extraction. : e p y t , t p m o r p S S A R G e h t t a , s s m . e p a t . i n u r o T 3 s s m . e p a t . i
The first prompt in i.tape.mss asks for the tape device name. This is sometimes /dev/rmt0 (for a . e n i h c a m h c a e h t i w s e i r a v s i h t t u b , ) 0 0 6 1 f o y t i s n e d e p a t
The next prompt is:
Please mount and load tape, then hit RETURN -->
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
MASSCOMP users may first have to assign the tape drive the appropriate density. Frequently, the density of the
2
data stored on tape is 1600 bpi (bytes per inch). The relevant command to assign the tape drive is then usually assign . x 0 0 6 1 n g i s s a r o 0 0 6 1
MASSCOMP users may first have to assign the tape drive the appropriate density. Frequently, the density of the
3
data stored on tape is 1600 bpi (bytes per inch). The relevant command to assign the tape drive is then usually assign . x 0 0 6 1 n g i s s a r o 0 0 6 1
n e e r c S n o i t a c fi i t n e d I S S M . 1 . 2 . 1 . 7
After hitting RETURN the first screen in the program asks for information about the data.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
please enter the following information
: n o i t a c fi i t n e d I e p a T Image Description:
Title for the Extracted Cell Files:
AFTER COMPLETING ALL ANSWERS, HIT<ESC>TO CONTINUE ) L E C N A C O T > C -l r t C < R O ( __________________________________________________________________ e h t d n a r e b m u n D I e n e c s e h t s r e t n e y l l a c i t a m o t u a m a r g o r p e h t , r e d a e h e p a t e h t m o r f n o i t a m r o f n i g n i s U
date of the image into the field for Tape Identification. The sun angles are automatically entered into s i t i , d e h c u o t n u t f e l , t u b , r e s u e h t y b d e t i d e e b n a c n o i t a m r o f n i s i h T . n o i t p i r c s e D e g a m I r o f d l e fi e h t
accurate and informative. The user should enter other pertinent information and the title for the o t n i y l l a c i t a m o t u a d e r e t n e e r a n o i t p i r c s e d e g a m i e h t d n a n o i t a c fi i t n e d i e p a t e h T . s e l fi r e t s a r d e t c a r t x e
the history files for the raster files by GRASS. n o i t c a r t x E n m u l o C d n a w o R . 2 . 2 . 1 . 7
The second screen is:
__________________________________________________________________ N O I T C A R T X E E P A T S S M
please select the desired tape region to extract
) 4 8 9 2 -1 ( _ _ _ _ _ _ _ : w o r t s r fi last row:_______(1-2984) first col:_______(1-3548) last col:_______(1-3548) E U N I T N O C O T > C S E < T I H , S R E W S N A L L A G N I T E L P M O C R E T F A (OR____<__Ctrl-C_____>__TO CANCEL)________________________________ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ e h t n o ) s o r e z ( r e l l fi g n i d u l c n i s n m u l o c d n a s w o r f o s r e b m u n l a t o t e h t e r a s e s e h t n e r a p n i s r e b m u n e h T
tape, which is obtained from the tape. This information and additional information can be obtained by S S M e h T . e p a t S S M n a n o n o i t a m r o f n i r e d a e h e h t s d a e r h c i h w , m a r g o r p h . s s m . e p a t . i e h t g n i n n u r
header contains the scene center latitude and longitude and the number of rows and columns in the , e p a t a n o s e l fi f o r e b m u n e h t e d i v o r p d n a e p a t y n a d a e r o s l a l l i w m a r g o r p e p a t . e n i m a x e . m e h T . e n e c s
the number of records on a tape, and the record lengths. The number of records in a file is the number . s n m u l o c f o r e b m u n e h t s i h t g n e l d r o c e r e h t d n a , e l fi a n i s w o r f o
Any subset of the image on the tape can be extracted. To find the row and column numbers : l u f p l e h e r a n o i t a m r o f n i f o s e c r u o s l a r e v e s , e g a m i S S M n a f o t e s b u s a y f i t n e d i o t d e d e e n
1 The information from the tape header
2 The corner point latitudes and longitudes of the image from the Landsat search printout e g a m i e h t f o s p a m e t u n i m -5 1 d n a e t u n i m -5 . 7 e h t f o n o i t i s o p e h t f o m a r g a i d A 3
e l b a l i a v a f i e g a m i e h t f o h p a r g o t o h p A 5
6 A printout describing information about the image if it comes with the tape
n a f o d n a b e n o , e l b a l i a v a s i e c a p s k s i d h g u o n e f I . l u f p l e h o s l a e r a s d n a m m o c y a l p s i d S S A R G
entire image or, one band of a portion of an image known to contain the area of interest, can be . d e y a l p s i d d n a d e t c a r t x e
The x,y coordinates of the displayed image can be echoed to the screen using the measurements l l i w s e t a n i d r o o c e s e h T ( . ) t s a r . d f o e s u e h t g n i w o l l o f ( d n a m m o c e r e h w . d e h t r o , y a l p s i d . d n i n o i t p o
display negative numbers in the north-south direction but, by ignoring the negative sign, the correct row ) . d e t r o p e r s i r e b m u n
To find the area of interest using these display options in GRASS, the features displayed on the -i t a l ( e g a m i e h t f o s e t a n i d r o o c n w o n k e h t s p a m e h t n o g n i t a c o l y b s p a m e h t n o d n u o f e b n a c r o t i n o m
tude and longitude) and looking for the displayed physical features. If the latitude and longitude coor-p l e h o t d o h t e m e n o , ) s p a m 0 0 0 4 2 : 1 y n a m , e l p m a x e r o f ( s d n u o b r i e h t n i h t i w s p a m y n a m n i a t n o c s e t a n i d
locate the area of interest is described as follows:
1 Draw an approximate square or rectangle representing the entire image stored on tape. d n a ) n w o n k f i t n i o p r e t n e c d n a ( s t n i o p r e n r o c e d u t i g n o l d n a e d u t i t a l n w o n k e h t y f i t n e d I
mark these on the square. Section the "square" into a grid and approximate the latitude and . n o i t c e s r e t n i d i r g h c a e r o f e d u t i g n o l
2 Based on the known latitude and longitude corner points for the image, gather together all r e h t o n a w a r D . g n o l / t a l e h t n i h t i w d e n i a t n o c e r a t a h t ) e l a c s e t a i r p o r p p a n a f o ( s p a m e h t f o
square and section it into a grid in which each cell represents a map. Mark the latitude and . n o i t c e s r e t n i h c a e f o e d u t i g n o l
3 Locate your area of interest on the square that represents the grid of maps (step 2).
u o y , " e r a u q s p a m " e h t n o g n o l / t a l e h t d n a , " e r a u q s e g a m i " e h t n o g n o l / t a l e h t t a g n i k o o l y B 4
can determine in what grid cells of the image the features you are interested in lie. You -i n o m y a l p s i d e h t n o e g a m i e h t f o s t n e l a v i u q e l l e c d i r g e t a i r p o r p p a e h t o t n i -m o o z n e h t n a c
tor and try to match the features displayed on the monitor with those on the map.
-s a e m e h t r o e r e h w . d e s u n a c u o y , e g a m i e h t n o t s e r e t n i f o a e r a r u o y d n u o f e v a h u o y e c n O 5
urements option in d.display to determine the row and column numbers for the four corners e b o t n m u l o c t s a l d n a , n m u l o c t s r fi , w o r t s a l , w o r t s r fi e h t e r a s e u l a v e s e h T . a e r a e h t f o
entered in the tape extraction screen.
If a photograph of the digital image is available, the rows and columns to be extracted can also e h t n i s n m u l o c d n a s w o r n w o n k f o r e b m u n l a t o t e h t h t i w s e h c n i g n i t a i c o s s a y b t i m o r f d e n i m r e t e d e b
scene. For example, if the total length of the photograph is 12 inches, the total number of rows on the , o t o h p e h t f o p o t e h t m o r f s e h c n i 2 s n i g e b t s e r e t n i f o a e r a e h t f o r e n r o c t s e w h t r o n e h t d n a , 0 0 0 2 s i e p a t then: 12" / 2000 rows = 2" / x rows 3 3 3 . 3 3 3 = x
The northwest corner of the area of interest starts at row 333. The starting row, ending row, starting . r e n n a m s i h t n i d e t a l u c l a c e b n a c n m u l o c g n i d n e d n a , n m u l o c 7.1.2.3. MSS Band Extraction
: s i n e e r c s t x e n e h T __________________________________________________________________ d e t c a r t x e t n a w u o y s d n a b e h t y b x n a e k a m e s a e l p _____1 _____2 _____3 _____4 E U N I T N O C O T > C S E < T I H , S R E W S N A L L A G N I T E L P M O C R E T F A (OR____<__Ctrl-C_____>__TO CANCEL)________________________________ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ e h t f o l l a e c n i S . s d n a b e s e h t f o t e s b u s a y l n o t c a r t x e o t t n a w y a m u o y t u b s d n a b 4 s a h y r e g a m i S S M
bands can be extracted from tape now and gathered together in different combinations for different : e b t h g i m s d n a b r e w e f g n i t c a r t x e r o f s n o s a e r , p u o r g . i d n a m m o c e h t g n i s u r e t a l s n o i t a c i l p p a
1 For initial identification of the area of interest; extract one band first to locate the area of r o , ) n o i t c a r t x E n m u l o C d n a w o R . 2 . 2 . 1 . 7 n o i t c e s b u s e e s ( t s e r e t n i
2 For application purposes; the application requires only the use of some of the bands. e m a N p u o r G / x fi e r P . 4 . 2 . 1 . 7
You are then asked to enter the prefix/group for the band raster files to be created. This name g n i w o l l o f e h t d e t c a r t x e e r a s d n a b 3 f i , e l p m a x e r o F . S S A R G o t n i d e t c a r t x e e l fi d n a b h c a e e d e c e r p l l i w
3 band files will result:
prefixname.1 2 . e m a n x fi e r p prefixname.3 g n i e b e l fi p u o r g y r e g a m i e h t r o f e m a n e h t e m o c e b y l l a c i t a m o t u a o s l a l l i w e m a n x fi e r p d e fi i c e p s e h T
created. Each MSS image (i.e., each MSS tape set) should be given a unique prefix/group name. Any y r e g a m i e m a s e h t o t n i d e t c a r t x e e b n a c t e s e p a t r o e g a m i S S M e n o m o r f s t e s b u s e g a m i f o r e b m u n
group (same prefix/group name), even if they all have different row/column coordinates. Only different -a e r e h T . s p u o r g y r e g a m i t n e r e ff i d o t n i d e t c a r t x e e b d l u o h s ) s t e s e p a t S S M t n e r e ff i d , . e . i ( s e g a m i S S M
son for this is that the purpose of an imagery group is to identify raster files for classification and . t e s e p a t S S M o t t e s e p a t S S M m o r f y r a v s e i t r e p o r p n o i t a c fi i t c e r d n a n o i t a c fi i s s a l c d n a , n o i t a c fi i t c e r
7.1.2.5. The Extraction Process
The extraction process will begin by first skipping the number of specified files, advancing to the e h t n o d e y a l p s i d s i n o i t c a r t x e e h t f o n o i t e l p m o c t n e c r e p e h T . e p a t e h t g n i d a e r n e h t d n a , w o r g n i t r a t s
screen. If more than one tape is required to store the image, the program will pause and inform you to . e p a t t x e n e h t t n u o m
Note: After extracting an image from tape, the mapset region in the x,y coordinate LOCATION will Y R E G A M I E H T 5 n o i t c e s e e s ( e p a t e h t m o r f s n m u l o c d n a s w o r d e t c a r t x e e h t n o p u d e s a b t e s e b
LOCATION, subsection 5.1. Creating an X,Y Coordinate LOCATION, and section 6, REGIONS . ) S K S A M D N A 7.1.2.6. MSS Output
The extracted band files will be listed as raster files available in the current MAPSET and may be . s t n i o p . i r o t s a r . d , y a l p s i d . d d n a m m o c S S A R G e h t r e h t i e g n i s u d e y a l p s i d
Note: If more than one image or image subset is extracted into the same x,y LOCATION, and the s n m u l o c d n a s w o r e h t n o d e s a b e r a h c i h w ( s n o i g e r t e s p a m t n e r e ff i d e v a h s t e s b u s e g a m i r o s e g a m i
extracted), then, to display a raster file in the LOCATION, you will have to check the current MAPSET -c e s e e s n o i t a n a l p x e d e l i a t e d a r o F . d e y a l p s i d e b o t e l fi r e t s a r e h t s e h c t a m t i t a h t e r u s e k a m o t n o i g e r
tion 6, REGIONS AND MASKS. g n i h c t a P t u o b A . 3 . 1 . 7
When more than one MSS image is needed (and therefore extracted) in order to include an entire o t t n a w y a m u o y e c n e u q e s g n i s s e c o r p e g a m i e h t n i t n i o p e m o s t a , n o i t a c i l p p a n a r o f t s e r e t n i f o a e r a
unite the images. In GRASS 4.0 the program to accomplish this is r.patch. See section 15, PATCH-. h c t a p o t w o h d n a n e h w t u o b a n o i t a m r o f n i r o f S E G A M I G N I
7.2. Extracting TM Imagery From Tape
Note: Please become familiar with section 6, REGIONS AND MASKS before running a tape extrac-.
n o i t
This program must be run in a LOCATION with an x,y coordinate system (for further information see . ) N O I T A C O L Y R E G A M I E H T , 5 n o i t c e s
i.tape.tm is the GRASS program that extracts Thematic Mapper (TM) imagery from tape. When d e s o p a t x u j e b l l i w y e h t , t n e s e r p e r a s d a u q r u o f l l a f I . s d a u q r u o f n i d e r o t s s i t i , d e r u t p a c s i e g a m i M T a
on the image as follows:
_______ 2 1 _______ 4 3 _______ . y l e t a r a p e s d e t c a r t x e e b t s u m d a u q h c a e , e r o f e r e h t d n a , e g a m i e t a r a p e s a s a e p a t n o d e r o t s s i d a u q h c a E
Each quad will require a new run of i.tape.tm.
Before running a tape extraction, it is a good idea to check to see if there is enough disk space -i t l u m y b d e t a l u c l a c e b n a c d a u q M T a n i s e t y b f o r e b m u n e h T . e n i h c a m r u o y n o s e l fi d e t c a r t x e e h t r o f
plying the number of rows in the quad by the number of columns in the quad and then multiplying that a n i s n m u l o c d n a s w o r f o r e b m u n e h t g n i n i m r e t e D . d e t c a r t x e e b o t s d n a b f o r e b m u n e h t y b r e b m u n
TM quad is explained in subsection 7.2.2., Row and Column Extraction. : e p y t t p m o r p S S A R G e h t t a , m a r g o r p e h t n i g e b o T 4 m t . e p a t . i
The first prompt in i.tape.tm asks for the tape device name. This is sometimes /dev/rmt0 (for a . e n i h c a m h c a e h t i w s e i r a v s i h t t u b , ) 0 0 6 1 f o y t i s n e d
The next prompt is:
Please mount and load tape, then hit RETURN --> n e e r c S n o i t a c fi i t n e d I M T . 1 . 2 . 7 __________________
MASSCOMP users may first have to assign the tape drive the appropriate density. Frequently, the density of the
4
data stored on tape is 1600 bpi (bytes per inch). The relevant command to assign the tape drive is then usually assign . x 0 0 6 1 n g i s s a r o 0 0 6 1
After hitting RETURN the first screen in the program asks for information about the data. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
please enter the following information
: n o i t a c fi i t n e d I e p a T Image Description:
Title for the Extracted Cell Files:
AFTER COMPLETING ALL ANSWERS, HIT<ESC>TO CONTINUE ) L E C N A C O T > C -l r t C < R O ( __________________________________________________________________ -s i m e h T . n o i t a c fi i t n e d I e p a T r o f d l e fi e h t o t n i r e b m u n D I e n e c s e h t s r e t n e y l l a c i t a m o t u a m a r g o r p e h T
sion, path, row, quadrant, date, and whether the image is corrected is automatically entered into the -u c c a s i t i , d e h c u o t n u t f e l , t u b r e s u e h t y b d e t i d e e b n a c n o i t a m r o f n i s i h T . n o i t p i r c s e D e g a m I r o f d l e fi
rate and informative. The user should enter other pertinent information and the title for the extracted y r o t s i h e h t o t n i y l l a c i t a m o t u a d e r e t n e e r a n o i t p i r c s e d e g a m i e h t d n a n o i t a c fi i t n e d i e p a t e h T . s e l fi r e t s a r
files for the raster files by GRASS. n o i t c a r t x E n m u l o C d n a w o R . 2 . 2 . 7
The second screen is:
__________________________________________________________________ T C A R T X E R E P P A M C I T A M E H T
please select the desired tape region to extract
) 4 8 9 2 -1 ( _ _ _ _ _ _ _ : w o r t s r fi last row: _______(1-2984) ) 0 2 2 4 -1 ( _ _ _ _ _ _ _ : l o c t s r fi last col:_______(1-4220) E U N I T N O C O T > C S E < T I H , S R E W S N A L L A G N I T E L P M O C R E T F A (OR____<__Ctrl-C_____>__TO CANCEL)________________________________ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ r e l l fi d n a a t a d e g a m i g n i n i a t n o c s n m u l o c d n a s w o r f o r e b m u n l a t o t e h t e r a s e s e h t n e r a p n i s r e b m u n e h T
(zeros) on the tape. The last row of each quad contains zeros. Quads 1 and 2 contain 2983 rows of w o r t s a l e h t t c a r t x e o t t o n t s e b s i t I . a t a d e g a m i f o s w o r 2 8 9 2 n i a t n o c 4 d n a 3 s d a u q d n a , a t a d e g a m i
(row 2984 on Quads 1 and 2 and row 2983 on Quads 3 and 4) because, if Quad 1 is patched to Quad 3 e h t h g u o r h t t s e w d n a t s a e g n i n n u r a t a d o n f o e n i l a t l u s e r l l i w e r e h t , 4 d a u Q o t d e h c t a p s i 2 d a u Q r o
image. If TM quads are to be patched side to side, you will also want to avoid extracting the zeros on . e c a p s k s i d y r a s s e c e n n u p u e k a t o s l a l l i w , e s r u o c f o , s o r e Z . d a u q h c a e f o s e d i s t h g i r d n a t f e l e h t
Methods to identify the row and column coordinates to be extracted from a TM quad are described . w o l e b
Any subset of the quad on the tape can be extracted. To find the row and column numbers : l u f p l e h e r a n o i t a m r o f n i f o s e c r u o s l a r e v e s , d a u q M T a f o t e s b u s a y f i t n e d i o t d e d e e n
1 The center point and corner point latitudes and longitudes of the image from the Landsat t u o t n i r p h c r a e s
2 A diagram of the position of the 7.5-minute and 15-minute maps of the image relative to s d a u q M T e h t
d a u q e h t f o s p a m e t u n i m -5 1 d n a -5 . 7 e h T 3
4 A photograph of the image if available
e p a t e h t h t i w s e m o c t i f i e g a m i e h t t u o b a n o i t a m r o f n i g n i b i r c s e d t u o t n i r p A 5
GRASS display commands are also helpful. If enough disk space is available, one band of an d e t c a r t x e e b n a c , t s e r e t n i f o a e r a e h t n i a t n o c o t n w o n k d a u q a f o n o i t r o p a f o d n a b e n o r o d a u q e r i t n e
and displayed. Running the measurements option in d.display or d.where (following the use of d.rast) y a l p s i d l l i w s e t a n i d r o o c e s e h T ( . n e e r c s e h t n o d a u q d e y a l p s i d e h t f o s e t a n i d r o o c y , x e h t o h c e l l i w
negative numbers in the north-south direction but, by ignoring the negative sign, the correct row ) . d e t r o p e r s i r e b m u n
To find the area of interest using these display options in GRASS, the features displayed on the e d u t i t a l ( d a u q e h t f o s e t a n i d r o o c n w o n k e h t s p a m e h t n o g n i t a c o l y b s p a m e h t n o d n u o f e b n a c r o t i n o m
and longitude) and looking for the displayed physical features. If the latitude and longitude coordinates e t a c o l p l e h o t d o h t e m e n o , ) s p a m 0 0 0 4 2 : 1 y n a m , e l p m a x e r o f ( s d n u o b r i e h t n i h t i w s p a m y n a m n i a t n o c
the area of interest is described below.
1 Draw an approximate square or rectangle representing the entire quad stored on tape. Iden-M T e h t r o f t n i o p r e t n e c e h t g n i s u ( s t n i o p r e n r o c e d u t i g n o l d n a e d u t i t a l n w o n k e h t y f i t
image) and mark these on the square. Section the square into a grid and approximate the . n o i t c e s r e t n i d i r g h c a e r o f e d u t i g n o l d n a e d u t i t a l
2 Based on the known latitude and longitude for the quad, gather together all of the maps (of -c e s d n a , e r a u q s r e h t o n a w a r D . g n o l / t a l e h t n i h t i w d e n i a t n o c e r a t a h t ) e l a c s e t a i r p o r p p a n a
tion it into a grid in which each cell represents a map. Mark the latitude and longitude of . n o i t c e s r e t n i h c a e
3 Locate your area of interest on the square that represents the grid of maps (step 2).
u o y " , e r a u q s p a m " e h t n o g n o l / t a l e h t d n a " , e r a u q s d a u q " e h t n o g n o l / t a l e h t t a g n i k o o l y B 4
can determine in what grid cells of the quad the features you are interested in lie. You can d n a r o t i n o m y a l p s i d e h t n o d a u q e h t f o s t n e l a v i u q e l l e c d i r g e t a i r p o r p p a e h t o t n i -m o o z n e h t
try to match the features displayed on the monitor with those on the map.
r o e r e h w . d e s u n a c u o y , d a u q d e y a l p s i d e h t n o t s e r e t n i f o a e r a r u o y d n u o f e v a h u o y e c n O 5
the measurements option in d.display to determine the row and column number for the four n m u l o c t s a l d n a , n m u l o c t s r fi , w o r t s a l , w o r t s r fi e h t e r a s e u l a v e s e h T . a e r a e h t f o s r e n r o c
to be entered in the tape extraction screen.
If a photograph of the TM image is available, the rows and columns to be extracted can also be e h t n i s n m u l o c d n a s w o r n w o n k f o r e b m u n l a t o t e h t h t i w s e h c n i g n i t a i c o s s a y b t i m o r f d e n i m r e t e d
scene. For example, if the total length of the photograph is 12 inches, the total number of rows on the , o t o h p e h t f o p o t e h t m o r f s e h c n i 2 s n i g e b t s e r e t n i f o a e r a e h t f o r e n r o c t s e w h t r o n e h t d n a , 0 0 0 2 s i e p a t then: 12" / 2000 rows = 2" / x rows 3 3 3 . 3 3 3 = x
The northwest corner of the area of interest starts at row 333. The starting row, ending row, starting . r e n n a m s i h t n i d e t a l u c l a c e b n a c n m u l o c g n i d n e d n a , n m u l o c
: s i n e e r c s t x e n e h T __________________________________________________________________ d e t c a r t x e t n a w u o y s d n a b e h t y b x n a e k a m e s a e l p _____1 _____2 _____3 _____4 _____5 _____6 _____7 E U N I T N O C O T > C S E < T I H , S R E W S N A L L A G N I T E L P M O C R E T F A (OR____<__Ctrl-C_____>__TO CANCEL)________________________________ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ e h t f o l l a e c n i S . s d n a b e s e h t f o t e s b u s a y l n o t c a r t x e o t t n a w y a m u o y t u b s d n a b 7 s a h y r e g a m i M T
bands can be extracted from tape now and gathered together in different combinations for different : e b t h g i m s d n a b r e w e f g n i t c a r t x e r o f s n o s a e r , p u o r g . i d n a m m o c e h t g n i s u r e t a l s n o i t a c i l p p a
1 For initial identification of the area of interest; extract one band first to locate the area of r o , ) n o i t c a r t x E n m u l o C d n a w o R , . 2 . 2 . 7 n o i t c e s b u s e e s , t s e r e t n i
2 For application purposes; the application requires only the use of some of the bands. e m a N p u o r G / x fi e r P . 3 . 2 . 7
You are then asked to enter the prefix/group for the band raster files to be created. This name g n i w o l l o f e h t d e t c a r t x e e r a s d n a b 3 f i , e l p m a x e r o F . S S A R G o t n i d e t c a r t x e e l fi d n a b h c a e e d e c e r p l l i w
3 band files will result:
prefixname.1 2 . e m a n x fi e r p prefixname.3 g n i e b e l fi p u o r g y r e g a m i e h t r o f e m a n e h t e m o c e b y l l a c i t a m o t u a o s l a l l i w e m a n x fi e r p d e fi i c e p s e h T
created. Each TM quad (i.e., each quad tape set) should be given a unique prefix/group name. Any e m a s e h t ( p u o r g y r e g a m i e m a s e h t o t n i d e t c a r t x e e b n a c d a u q M T e n o m o r f s t e s b u s e g a m i f o r e b m u n
prefix/group name), even if they all have different row/column coordinates. Only different TM quads s i s i h t r o f n o s a e r e h T . s p u o r g y r e g a m i t n e r e ff i d o t n i d e t c a r t x e e b d l u o h s ) s t e s e p a t d a u q t n e r e ff i d , . e . i (
that the purpose of an imagery group is to identify raster files for classification and rectification, and . t e s e p a t d a u q o t t e s e p a t d a u q m o r f y r a v s e i t r e p o r p n o i t a c fi i t c e r d n a n o i t a c fi i s s a l c
Examples of prefix/group names for a TM quad might be 37quad1, 37quad2, 37quad3, and , w o r r o h t a p M T e h t s i " 7 3 " r e b m u n e h T . e g a m i M T a s i t i t a h t s e t a c i d n i " d a u q " d r o w e h T . 4 d a u q 7 3
whichever might distinguish it from another TM image, if more than one TM image of the same date is . e g a m i e h t f o d a u q e h t y f i t n e d i 4 d n a , 3 , 2 , 1 s r e b m u n e h T . N O I T A C O L y , x e m a s e h t o t n i d e t c a r t x e
All quads that will be patched should be extracted into the same x,y LOCATION (see 6.2.6., About . ) g n i h c t a P
7.2.4. The TM Extraction Process
The extraction process will begin by first skipping the number of specified files, advancing to the r o f s n m u l o c d n a s w o r d e t s e u q e r e h t g n i t c a r t x e r e t f A . e p a t e h t g n i d a e r n e h t d n a , d e t s e u q e r d n a b t s r fi
each band, the program creates support files for each band. The percent completion of the extraction is . s t e s e p a t e l p i t l u m n i d e r o t s s i t i , s d a u q 4 o t n i d e d i v i d s i y r e g a m i M T e s u a c e B . n e e r c s e h t n o d e y a l p s i d
The number of tapes required to store one quad depends on the number of bytes per inch (bpi) in which d n a e s u a p l l i w m a r g o r p e h t , d a u q e n o e r o t s o t d e r i u q e r s i e p a t e n o n a h t e r o m f I . d e r o t s e r a a t a d e h t
Note: After extracting an image from tape the mapset region in the x,y coordinate LOCATION will be -A C O L Y R E G A M I E H T , 5 n o i t c e s e e s ( e p a t e h t m o r f s n m u l o c d n a s w o r d e t c a r t x e e h t n o p u d e s a b t e s
TION; subsection 5.1., Creating an X,Y Coordinate LOCATION; and section 6, REGIONS AND . ) S K S A M 7.2.5. TM Output
The extracted band files will be listed as raster files available in the current MAPSET and may be . s t n i o p . i r o , t s a r . d , y a l p s i d . d s d n a m m o c S S A R G e h t g n i s u d e y a l p s i d
Note: If more than one image or image subset is extracted into the same x,y LOCATION, regardless t n e r e ff i d e v a h s t e s b u s e g a m i r o s e g a m i e h t f i d n a , p u o r g e m a s e h t o t n i d e t c a r t x e e r a y e h t r e h t e h w f o
mapset regions (which are based on the rows and columns extracted), then, to display a raster file in the e h t s e h c t a m t i t a h t e r u s e k a m o t n o i g e r T E S P A M t n e r r u c e h t k c e h c o t e v a h l l i w u o y , N O I T A C O L y , x
raster file to be displayed. For a more detailed explanation see section 6, REGIONS AND MASKS. g n i h c t a P t u o b A . 6 . 2 . 7
As was mentioned earlier, each quad requires a separate i.tape.tm extraction and each quad should o t , d e t c a r t x e s i d a u q e n o n a h t e r o m n e h W . ) p u o r g y r e g a m i ( e m a n p u o r g / x fi e r p e t a r a p e s a n e v i g e b
include an entire area of interest for an application, at some point in the image-processing sequence you n o i t c e s e e S . h c t a p . r s i s i h t h s i l p m o c c a o t m a r g o r p e h t , 0 . 4 S S A R G n I . s d a u q e h t e t i n u o t t n a w y a m
15, PATCHING IMAGES for information about when and how to patch. e p a T m o r F y r e g a m I l a t i g i D f o s e p y T r e h t O g n i t c a r t x E . 3 . 7
Note: Please become familiar with section 6, REGIONS AND MASKS before running a tape extrac-.
n o i t
This program must be run in a LOCATION with an x,y coordinate system (for further information, see . N O I T A C O L Y R E G A M I E H T , 5 n o i t c e s
i.tape.other is the GRASS program that extracts all other types of digital imagery from half-inch s t c a r t x e t a h t m a r g o r p c i r e n e g a s i m a r g o r p s i h T . ) y r e g a m i M T d n a y r e g a m i S S M n a h t r e h t o ( e p a t
imagery using the tape description that is input by the user. i.tape.other cannot extract images that con -n o c f l e s e r a t a h t s e g a m i t c a r t x e y l n o n a c t I . r e d a e h e m a s e h t g n i z i l i t u r e h t o n a o t e p a t e n o m o r f e u n i t
tained on one tape.
Note: i.tape.other must be run in a LOCATION with an x,y coordinate system (see section 5, THE . ) N O I T A C O L Y R E G A M I
Before running a tape extraction, it is a good idea to check to see if there is enough disk space -i t l u m y b d e t a l u c l a c e b n a c e g a m i n a n i s e t y b f o r e b m u n e h T . e n i h c a m r u o y n o s e l fi d e t c a r t x e e h t r o f
plying the number of rows in the image by the number of columns in the image and then multiplying r e b m u n e h t e n i m r e t e d o t w o h n o n o i t a m r o f n i r o F . d e t c a r t x e e b o t s d n a b f o r e b m u n e h t y b r e b m u n t a h t
of rows and columns in an image, refer to subsection 7.3.5., Generic Row and Column Screen. : e p y t t p m o r p S S A R G e h t t a , r e h t o . e p a t . i n i g e b o T 5 r e h t o . e p a t . i
The first prompt in i.tape.other asks for the tape device name. This is sometimes /dev/rmt0 (for . e n i h c a m h c a e h t i w s e i r a v s i h t t u b , ) 0 0 6 1 f o y t i s n e d a __________________
MASSCOMP users may first have to assign the tape drive the appropriate density. Frequently, the density of the
5
data stored on tape is 1600 bpi (bytes per inch). The relevant command to assign the tape drive is then usually assign . x 0 0 6 1 n g i s s a r o 0 0 6 1
