Shaded Relief

Use the Grid and Image > Filters > Shaded Relief menu option (GRIDSHAD GX) to create a shaded relief image from a grid. You must then combine the shaded grid with the original grid to produce a grid composite in your map.

This method is ideal for creating quick images or for creating images from a Geosoft Script file. You should be aware, however, that the final format of a manual image is not compatible with an interactive image. Therefore, if you want to shade the grid interactively, use the Display Image dialog to display the grid in a Map window and then shade it interactively using the dynamic functionality provided in the Interactive Shading for producing and modifying a shaded relief image based on a grid.

Shaded Relief dialog options

Input grid

Input grid file name

Script Parameter: GRIDSHAD.IN

Output shaded grid

Output shaded relief grid

Script Parameter: GRIDSHAD.OUT

Illumination inclination

Illumination inclination, 0 degrees (horizontal) to 90 degrees (vertical). The default is 45.

Script Parameter: GRIDSHAD.INC

Illumination declination

Illumination declination, 0-360 degrees azimuth. The default is 45 (N 45 E).

Script Parameter: GRIDSHAD.DEC

Vertical scale factor

Vertical scale factor, m/z unit. A default is calculated from the grid image.

Script Parameter: GRIDSHAD.SCL

Application Notes

  • The output image values will be the input image surface reflectance coefficients in the range -1 to 1. A reflectance of 1 means the image surface faces the light source; 0 means the surface is parallel to the light source; and -1 means the surface is facing completely away from the light source.

  • Use a grey or lgray colour table to display a shaded relief image. NORMAL colour zoning usually produces acceptable results.

  • The scale factor to use for a given data set is entirely dependent on the type of data, and can vary by many orders of magnitude. The most common approach is to first default the scale factor to see what the program produces. If the new image has too much relief (contrast), reduce the scale factor. If the image is too flat, increase the scale factor.

  • The output grid produced will be one cell smaller in dimension than the input grid, and the origin will be displace one-half cell in the positive X and Y directions.