Module 3

Working with Grids

April 2014

Eric Böker

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In this module you will learn: • How to load a Grid using Saga

• Set a Coordinate Reference System to your Grid

• Stretch the colour schemes of you Grid

• Perform a Terrain Analysis using the Interactive profiles module

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Load a Grid that is in your Folder C:\Users\XXX\Desktop\SagaCourse\Data\Gridsfiles Choose: As.sgrd Note that in Saga the grids extension is: .sgrd

Once the Grid is Loaded check in the Messages Window for any error messages. In the Manager Window under Data/Tree you will see the Grid: 01.AS. With the Name: 50; 5707x 3935y; 214832.576585x 7481345.87525y

Explain.

How to load a Grid using Saga

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Once your Grid is selected in the Manager Window, check the Object Properties Window under Description. Details description of your AS Grid is found. Note that under Projection you read Undefined Coordinate System. The Next step will be to set a Coordinate Reference System to your Grid. In the Manager Window, Select the Modules Tab, Right Click the Modules Libraries Icon and Type Proj.4 and Okay button. The Module Libraries locates the Modules and now you can choose from the list the Appropriate module. Set Coordinate Reference System: Define or change the Coordinate Reference System (CRS) associated with the supplied data sets.

Set a Coordinate Reference System to your Grid

Double Click the Module: Set Coordinate Reference System In the new Tab, under Data Objects/Grid select the grid you want to assign the Coordinate System. In Our case the AS.sgrd Then under Project Parameters/User Defined select from the drop down list the UTM

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Set a Coordinate Reference System to your Grid

Under UPGS code/Geographic Coordinates Systems, select WGS84

Under UPGS code/Projected Coordinates Systems, select WGS84/UTM zone 34S

The Set Coordinate Preference System Module should look like this: Note the EPSG Code 32734 for further use See also http://www.epsg-registry.org/

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Set a Coordinate Reference System to your Grid

Click the Okay button to execute the module. Check the messages Window/General. You can read in Green that the module execution succeeded. Under Objects Properties Window/Description once the AS.sgrd is selected the full description of the file shows you that now its reference projection system is correct.

Click the Add the Map/New command to appear the As grid in a new window. As you can see the appearance of the As grid is not so nice.

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Set a Coordinate Reference System to your Grid

Reorganise your work space with the AS grid, the road shape and the Histogram of the AS values. From the Histogram read the interval of AS values. In the Object Properties Windows/Settings under Colors/Scaling you can also read the value range of the AS grid. Change the Scaling/Mode option to Logarithmic (up) with Logarithmic Stretch Factor of 100. Play around until the your happy with the stretching factor. Note that the values of the Grid do not change its only the colour stretch who does (Histogram)

Stretch the colour schemes of you Grid

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In the properties Window tick the Show Cell Values. Apply the changes and see that for each Cell the actual values is shown. You can change the Boundary Effect using the drop down menu select “none” for example. In the display Properties see the effect of using Interpolation Bilinear on the Grid.

Stretch the colour schemes of you Grid

http://www.saga-gis.org/en/index.html

Follow the same steps and add to the existing AS the RTP1dv Layer grid. Move the AS on Top (Module2) On the Workspace Click the Modules button and select Terrain Analysis/Profiles [Interactive] In the new tab select the Grid System and Select for the >>DEM option a grid that you want to see and work when orientating our profiles. Under >Values Select any available grid on which you want to extract values from you profiles Position (AS and RTP1dv).

Perform a Terrain Analysis using the Interactive profiles module

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Zoom to the Fortuna/Fiesta anticline closure. Select the action button On the AS grid Left Click your mouse to the point where you want to start a profile and drag the Action Arrow to the point where you want the profile to stop. Then right Click your mouse to end the interactive profiling. A yellow line was drown. In the Manager Window under Data/Tree 2 new shapes were added. Line and Point shape were added with the name: Profile [AS]

• Perform a Terrain Analysis using the Interactive profiles module

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Right Click in the Manager Window the Profile [AS] new shape until you select Diagram under Attributes.

Select under the Attributes the Attributes you want to be shown in the Diagram. For the X axis select Distance. Press Okay. Following the previous described steps make new profiles and see that the Profile Diagram changes automatically

• Perform a Terrain Analysis using the Interactive profiles module

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The End

Any Questions ????