Tutorial case study D (GIS import)

(1)

Tutorial case study D (GIS import)

Parent topic: 3D

GeoModeller User Manual and Tutorials

Author: Desmond Fitzgerald, Intrepid Geophysics Editor: Claire Edwards, Intrepid Geophysics Update V2012: Stewart Hore

In this case study:

• Tutorial D1—GIS import

Tutorial D1—GIS import

Parent topic: Tutorial case study D (GIS import)

Making use of existing 2D maps, Arc Shape files, etc. In this tutorial:

• D1 Tutorial Overview

• D1 Stage 1—Start the project, define properties, choose projection and load DTM

• D1 Stage 2—Open points list editor and import shape files

• D1 Stage 3—Add geological formation A1 and assign shape as a boundry for this unit

• D1 Extensions to Geophysics

D1 Tutorial Overview

Parent topic: Tutorial D1—GIS import

• Prior interpretations of Geology captured in GIS • This takes the form of many parts such as

• Solid geology • Dykes • Faults

• Commonly in attributed shape files

• We wish to review this information in the context of building a 3D model, but only that which falls within the project box

• May have to convert the projections

• May have to weed or thin the line work as it is overspecified for what it is • May have to do some graphical adjustments before acceptance into the model • This data has to have added input from the user as to exactly what it represents in a

3DGeomodel context

Solution

• Bring GIS data into the Plan view Points Editor

• Only show the data that falls in the project box - clip to the edges

• Allow the User to edit/review and then classify exactly what the GIS data represents • Geology boundary

• Fault

(2)

Bowen Basin Example

• 2003 study area, approximately 200 * 200km in Queensland • Compliation of all geophysics, topography

• Interpreted geology, faults, dykes, anomalies

• Mostly captured in ArcShape files with Coordinate System of GDA94/Map Grid of Australia, Zone 55

Stages of the tutorial

• D1 Stage 1—Start the project, define properties, choose projection and load DTM

• D1 Stage 2—Open points list editor and import shape files

• D1 Stage 3—Add geological formation A1 and assign shape as a boundry for this unit

D1 Stage 1—Start the project, define properties, choose projection and load DTM

D1 Stage 1—Steps

1 Create a project with the following parameters:

• Name: TutorialD (Note: No spaces!) • Authors: your name

• Description: a comment of your choice • Projection: GDA94/MGA zone 55 • Unit: m • Geographical area: XMin = 600000. XMax = 650000. YMin = 7550000. YMax = 7600000. ZMin = –9000. ZMax =1000 .

Choose menu option Project > New. 3D GeoModeller displays the Project properties

dialog box. Complete the fields as given above and choose OK.

(3)

2 Load DTM with paremameters as shown below.

Create topographic surface From a DTM with the following properties:

• Name: Topography

• Filename:

GeoModeller\tutorial\CaseStudyD\TutorialD1\Data\dtm2.ers

• Description: a comment of your choice

Choose From a DTM in the Project creation successful dialog box. 3D GeoModeller displays the Load topography from an ASCII grid dialog box.

Enter the Name and Description fields as shown above and choose Browse to navigate to

GeoModeller\tutorial\CaseStudyD\TutorialD1\Data\dtm2.ers

Choose OK.

3D GeoModeller opens a 3D Viewer, which shows the bounding box of your project.

3 Save the project. From the main menu, choose Project > Save As, navigate to the directory where you want to save your work, assign a project name and save.

Note that a completed version of the tutorial is available in

GeoModeller\tutorial\CaseStudyD\TutorialD1\Completed_Project\

TutorialD1.xml. Do not overwrite it.

D1 Stage 2—Open points list editor and import shape files

1 Bring up the points list editor, expand to full table view and open a shape file using the file import option.

On the Points List Editor toolbar choose Float or dock the Points List Editor . From the Show Points List information or table menu in the toolbar choose Table .

(4)

From the toolbar select Show shape file input .

Choose Browse and navigate to

GeoModeller\tutorial\CaseStudyD\TutorialD1\Data\interp\ geology_solid.shp

Choose Open

Dock the points list editor by clicking on Float or dock the Points List Editor .

D1 Stage 3—Add geological formation A1 and assign shape as a boundry for this unit

1 Create a geological formation with the following parameters:

• Name: FormationD

• Colour: Light blue (RGB 0; 255; 255)

Choose main menu option Geology > Formations > Create–Edit.

In the Create–Edit geology formations dialog box, use the following sequence: • Enter the Name.

• Specify the Colour (Double click the Colour field and select the colour from the palette. Use the RGB tab if you want to get it exact, but this is not essential).

(5)

2 Assign shape as a boundary for FormationD:

In the Structural toolbar, choose Create geology data .

FormationD will be selected in the Geological Formations and Faults menu box as it is the only formation/fault

Choose Create and then Close. The shape should now be blue.

3 Add a second shape with high threshold and assign the shape to FormationD.

From the Points List Editor toolbar choose Float or dock the Points List Editor . Enter 16 into the Segment field and press Enter.

Set the Treshold level to High using the threshold slider (See below). There should now be 50 points in the points list.

Choose Float or dock the Points List Editor to dock the points list editor. From the Structural toolbar, select Create geology data .

FormationD will be selected in the Geological Formations and Faults menu box. Choose Create and then Close. The second shape should now be blue.

D1 Stage 3—Threshold discussion

The Threshold slider bar is used for weeding out unnecessary precision in the representation of the shape. Low threshold includes all original points, while high threshold gives about one third of the points without generally degrading the shape too much.

D1 Stage 3—General Comments

• This scheme relies on reliable geolocation of all your spatial data from different sources • Full projection and datum conversion facilities, are provided to do the on-the-fly changes • Can be used for ASCII csv files, Intrepid line and point datasets, Geosoft gdb.

• Is extensible to MapInfo with some work on a driver • Only proven for ArcShape files as yet

(6)

D1 Extensions to Geophysics

Euler

• This scheme has potential for Euler Clustered Depth Estimates to be managed in a Plan View • Threshold changed to pick on reliability

Geophysics Flight Line—Profile/Sections

• One could easily imagine selected flight lines from an airborne survey • Each line has a Geomodeller section

• These sections generated automatically

• A method such as Naudy giving possible 2D magnetric Dykes, dip, width and susceptibility

• Threshold used to control Similarity

Image Processing—Geophysical Grid Enhancements

• An additional layer in the plan view to cover the basic rendering and stretching of normal geophysical grid data sets

• Not just the import of a jpeg image