Terrain Shader Tutorial

Import DEM File

Geographic Imager will detect when elevation data is being opened in Adobe Photoshop. The Import DEM File dialog box will automatically open where you can specify a DEM schema and other settings.

1.In Adobe Photoshop, browse to the Tutorial Data folder and open Namu Water.dem from the \Tutorial Data folder.

2.In the Import DEM file dialog box, click the Create New Schema button.

This opens the Edit DEM Schema dialog box. The Schema Name is already populated with the name of the file. It also populates the Lowest and Highest Elevation values according to the DEM’s data range.

3.Since these values are acceptable, they do not need to be modified. Click OK.

4.The Select Schema now reflects the data range of the DEM.

5.In the Import DEM file dialog box, click the Advanced button.

The value -32767.00 in the Display as transparent pixels list is a predefined value that represents no data. This value can't be deleted and is common to all DEM files. To display elevations as transparent pixels, populate this list with elevation values.

6.Click the Add new value button. Double-click <new value> and enter a value of 0.

7.Click OK to close the Advanced DEM Schema Settings and click OK to accept the settings of the Import DEM file dialog box to finish the import.

The chosen custom DEM schema maps the range of elevation to the Adobe Photoshop grayscale colour-space, displaying the highest contrast possible. A transparent area is visible where all elevations with a value of 0 that was specified in Advanced DEM Schema Settings.

The elevation value of 0 is considered water for this DEM. Since the area that represents water is now transparent, it is now very easy to create a background layer and apply a different colour to it (remember that the colour-space is grayscale). In the next exercise, you will apply a gradient map to the elevation data layer using the Terrain Shader and also create a background.

8.Keep this document open for the next Terrain Shader tutorial.

Terrain Shader

Terrain Shader is used to style images with elevation data. You can quickly create a gradient map adjustment layer using predefined or custom colour maps.

1.Continue working with Namu Water.dem from the previous Import from DEM tutorial.

2.On the Geographic Imager panel, click the Terrain Shader button.

3.Click the Colourization Schema check box to enable its frame options. The Apply Colour Map option is chosen and automatically applies the first colour map (or the last colour ramp used) in the list. If it’s different than what you see in your dialog box, choose the World colour map.

The Create Single Layer option is checked by default which creates one gradient map adjustment layer. Unchecking this option will create a gradient map adjustment layer for each layer. The Use Continuous Colour option is also checked by default. It ensures the colour ramp has smooth transitions between colours instead of discrete colours.

4.Click the Import Colour Map From File button in the Colourization Schema frame (third button to the right of the colour map).Choose the file Colour Ramp Examples.grd from the Tutorial Data folder.

5.Choose Elevation 3 from the Colour Map drop-down list and click Import.

6.Choose Elevation 3 from the Colour Ramp drop-down list and then click the Edit Selected Colour Map button.

The Edit Colour Map dialog box shows how the elevation is mapped to the colour ramp. Hover over the colour ramp to see how the elevation values correspond to the chosen colour ramp.

7.Right-click the colour swatch of the table entry for Colour Stop 1 (at the top of the list) and click Edit Colour Stop. Alternatively, click the colour chip slider on the colour ramp.

8.In the Select Colour for Colour Stop dialog box.  Enter new colour values of Red: 204, Green: 198, Blue; 181.

9.Click OK to close the colour dialog box. Click Save and on the following dialog box, choose the Save as a new colour map option. Enter My Colour Map as the new name.

10. Click OK to return to the Terrain Shader dialog box.

11. Click the Apply Shaded Relief check box. Change the angle to 40 and adjust the Intensity to 35.

12. Click OK.

Your customized colour ramp is applied to the DEM. In the Layers panel, notice that the original DEM (and background) is maintained. The shaded relief and colour map layer are at the top of the layers list.

To add a background, simply create a new layer and position it at the bottom of the Layers list.

13. Create a new layer and rename it to Background. Use the Adobe Photoshop Paint Bucket Tool and fill the layer with a blue colour (R: 100, G: 130, B: 175).