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Adjust Color and Elevation

Eylon Sirotkin
  • Updated

Color and elevation adjustments can be made in a layer’s property sheet.

Color Adjustment

The RGB levels of an image layer can be adjusted in the Color Adjustment group of the Properties Sheet. The Color Adjustment group appears in the Properties Sheet only when at least one image layer is in Edit mode.

Note:   The values displayed in the histogram are based on the information currently displayed in the Working Window. For best results turn off the View mode of all other layers and fit the layers in Edit mode into the Working Window.

To adjust the color of an Image layer:

  1. In the Layer List, select Edit mode for the required layer(s). If more than one layer is selected, the Color Adjustment group displays values that are common to all the image layers.
  2. If you want to modify RGB levels by entering precise luminosity, gamma and saturation values, do the following:
    a.  In the Color Adjustment group of the Properties Sheet, select a Channel: RGB, Red, Green or Blue.
    b.  Type the required Luminosity, Gamma and Saturation values in the appropriate boxes.
  3. If you want to modify RGB levels by adjusting the RGB histogram:
    a.  In the Color Adjustment group of the Properties Sheet, click the Adjust button in the Histogram The Adjust Histogram dialog box is displayed.
    adjust_histogram.gif
    b.  From the drop-down list select a channel: RGB, Red, Green or Blue.
    c.  Move the sliders to set the required values.

Note:   A Luminosity value can be any number between 0 and 255. The maximum value must be greater than the minimum value. The Gamma value can be any number between 0.01 and 10.
The process that changes the luminosity value of each pixel in the image data to a new value is as follows:

  • The Minimum and Maximum Input Luminosity Values clip the original luminosity value (0 - 255).
  • The clipped value is transformed by the Gamma where:
      • Gamma = 1 = unchanged
      • Gamma > 1 = brighter
      • Gamma < 1 = darker
  • The transformed value is scaled to fit the range of the Maximum and Minimum Output Luminosity Values.

Scale Elevation

Scaling elevation values enables you to adjust elevation layers that are defined with reference to a baseline other than sea level, or in units other than meters. TerraBuilder assumes when displaying elevation data, that the source elevation information it read was in meters. If, however the elevation information provided was in a different unit of measure, for example, feet, you can convert the elevation data to meters by setting the required scale factor, so that the data displays accurately. In the example of feet to meters, the scale factor = 1 unit in layer/1 meter, which equals 0.3048.

The elevation data in the layer is changed to a new value where:

New Value = Old Value * Scale Factor + Offset Value

Note:   You must make sure that the units of measurement for the scaled elevations are consistent with the units for the Offset.

To scale elevation layer data:

    1. In the Layer List, select Edit mode for the required layer(s).
    2. In the Scale Elevation group of the Properties Sheet, in the Elevation Scale field, type a Scale Factor value for the elevation data in the selected layer(s).
    3. In the Elevation Offset field, type a value to be used as the offset for the elevation data in the selected layer(s).

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