Shader Options

The Shader Options section of Configuration controls options for the display of elevation data using the daylight, gradient, slope, and HSV shaders, as well as editing of Custom Shaders. Shaders are the color ramp or color steps that are applied to visualize terrain data by elevation value, slope or slope direction.

Access the Shader Options by selecting the configure button Configuration button from the File Toolbar or Tools menu, and navigating to the Shader Options section.

Surface Color

Sets the calculated surface intensity color.

Low Color

Sets the lowest elevation value color.

High Color

Sets lowest elevation range color.

Low Color Start (Advanced)

Sets where in the HSV color range the lowest elevation will be.

Value

Modifies the HSV value parameter.

Saturation

Modifies the HSV saturation parameter.

Range

Modifies how much of the full HSV range is to be used. Increasing this value leads to color wraparound.

Save HSV Options...

Save the current HSV options in a text file.

Load HSV Options...

Load a set of HSV options from a text file. Loading the options will change the sliders and the preview image, but will not be activated in GM until clicking the OK or Apply button.

Minimum Slope

Slope Value

Allows the user to set the slope at or below which the Minimum Slope Color is used.

Color

Specifies the color which all parts of the terrain with a slope at or below the Minimum Slope Value will be colored with.

Maximum Slope

Slope Value

Allows the user to set the slope at or above which the Maximum Slope Color is used.

Color

Specifies the color which all parts of the terrain with a slope at or above the Maximum Slope Value will be colored with.

Coloring Between Min and Max Slope Values

Smooth Gradient

Specifies that all portions of the terrain with a slope between the Minimum Slope Value and the Maximum Slope Value will be colored with a smooth gradient of colors that vary with the slope from the Minimum Slope Color to the Maximum Slope Color.

Custom Color

Specifies that all portions of the terrain with a slope between the Minimum Slope Value and the Maximum Slope Value will be colored with a single color that can be modified with the Select... button.

Slope Algorithm

Specify the neighborhood operation used to calculate the slope values. The slope value is calculated at a given pixel location based on the elevations in the surrounding pixels. The algorithm choice defines the size of the moving window used and the statistic.

The choices are:

  • Avg Maximum 4 Adjacent (Default) - calculates the average slope in a 3 X 3 circle surrounding the pixel (not including indirect neighbors connected by the corners, i.e. Rook's case).
  • Avg Maximum 8 Adjacent-calculate the average slope in a 3 X 3 square surrounding the pixel, including all direct and indirect neighbors (i.e. Queen's case).
  • Maximum 4 Adjacent- calculates the maximum slope in a 3 X 3 circle surrounding the pixel (not including indirect neighbors connected by the corners, i.e. Rook's case)
  • Maximum 8 Adjacent-calculate the maximum slope in a 3 X 3 square surrounding the pixel, including all direct and indirect neighbors (i.e. Queen's case).

East Color

Set the color to use for slopes facing directly East.

North Color

Set the color to use for slopes facing directly North.

South Color

Set the color to use for slopes facing directly South.

West Color

Set the color to use for slopes facing directly West.

ADVANCED: Offset Angle in Degrees

Specify an angle offset in degrees to add to the calculated slope direction in order to shade against slope directions other than cardinal directions.

The Custom Shaders dialog can be used to create . Custom shaders control exactly how elevation data is rendered in terms of how pixel values relate to colors.

To edit an existing custom shader, navigate to the Edit... button in Configuration Shader Options Custom Shader section.
The Delete button in Configuration Shader Options removes the currently selected custom shader.
Pressing the New... button displays the Custom Shader dialog (pictured below) which allows the user to create a new custom shader. New shaders can also be created from the Add Custom Shader...option on the Shader drop-down in the Viewer toolbar, or the Custom Shaders button on the Dynamic Hill Shading tool.

To create a new shader, enter a value in the Height/ Slope entry field. Press the Add button to specify the color associated with that value. Once the color is selected from the color picker, the swatch and value will be displayed in the Elevation/ Slope Colors list.

The Preview on the right side will show the shader color ramp, with a cross bar representing the location of the specified values. Check the Blend Colors Between Elevation/ Slope values option to create a continuous shader, or deselect it to create a classified shader.

The Custom Shader dialog specifies a custom elevation data color palette, and the relationship to the pixel values.

Name

The Name field provides a place to enter the name to associate with the shader to allow the user to select it. The Elevation Colors section display the elevations and their color values associated with the custom shader.

Elevation/ Slope Colors

This list displays the defined colors and values used in the shader.

Pressing the Change Color and Change Value buttons allow the user to change the values associated with the current elevation selected in the Elevation Colors list.

The Delete Value button deletes the currently selected elevation.

The Evenly Space Elevations Starting at Arbitrary Base Elevation button will allow you to quickly populate the list of elevation values with a series of evenly spaced values starting at some specified elevation. You can then assign the colors as desired after that. For example, you could use this to quickly populate the list with all elevations from 0 meters to 5000 meters with an elevation every 500 meters, then modify those as desired.

The Set Elevations to match REM shader… adjusts the elevation ranges for the currently selected colors while making the custom shader. This option lets you mimic the default REM shader with different colors, and further refine the elevations. To use this option, first specify your min and max elevation values or choose to Initialize from Other Shader.

REM shaders typically have bright colors at low elevations. To match this you will be prompted to reverse the colors in your chosen ramp.

New Height/Slope Entry

New elevations can be added by entering the elevation (in the currently selected units) and pressing the Add button.

Load existing shader options

The Initialize from Other Shader button will allow you to initialize the list of color/ elevation pairs to those used by either the Global Shader built into Global Mapper or another user-created custom shader. This allows users to easily create a slightly modified version of an existing shader if they'd like.

The Initialize from Palette File button allows you to initialize the list of color/ elevation pairs from a color palette file in any recognized format (like a comma-delimited file of R,G,B components on each line). Since palette files don't contain elevation values, the elevations will be incremented by one for each color and set to automatically scale the colors between loaded elevation values.

The Initialize from Surfer CLR File button allows you to initialize the list of color/elevation pairs with a a CLR file created by the Surfer application by Golden Software. You can use the Save to Surfer CLR File button to save your custom shader to a CLR file. This is useful for making copies of a custom shader and providing them to other users.

Additional Options

Elevations shaded with a custom shader will use the color specified for each elevation value. Any elevation values between two elevation/ color values will be a blend of the two bounding colors if the Blend Colors Between Elevation/ Slope Values option is checked. For example, if an elevation of 500 meters was set to black and an elevation of 1000 meters was set to white, an elevation of 750 meters would be colored a medium shade of gray. Any elevations below the minimum specified elevation will use the same color as the minimum elevation. The reverse is true for any elevations over the maximum elevation. If the blend colors option is not checked, any elevation between two elevation values will be set to the color associated with the lower of the elevation values.

To scale shader to the elevation range of the currently loaded data rather than stay at fixed elevation values, check the Scale Shader to Loaded Elevation Values. This will make your shader behave similar to most of the built-in shaders, like the Atlas or Color Ramp shaders. For example, if you check this option and specify that an elevation of 0 meters is blue and 1 meter is red, and the actual loaded data has a range of 100 meters to 500 meters, then 100 meters will be blue and 500 meters will be red, with the values gradually shaded in between (if you have the blend colors option checked).

Use the option to Repeat Color Range for Elevations Outside Range to repeat the defined colors for an elevation range when they go outside a specified range.

If you would like to shade based on the slope of the terrain rather than the elevation values, use the Shade Slope Values (Degrees) Rather than Elevations option. This will change the provided values so they are treated as slope angles in degrees and allow you to setup shading based on the slope.

This option will reverse the colors of the current Global Shader, visible in the shader drop-down menu on the Viewer toolbar, or on the Vertical Options tab.