Display Tab

The Display tab for Elevation Data (pictured below) contains controls allowing the user to control the color intensity (brightness/ darkness), color transparency, blending, anti-aliasing, and color shading of the selected layers.

Color Intensity

The Color Intensity setting controls whether displayed pixels are lightened or darkened before being displayed. It may be useful to lighten or darken raster overlays in order to see overlaying vector data clearly.

Translucency

The Translucency setting controls to what degree overlays underneath the selected overlay are visible. The default setting of Opaque means that underlying overlays will not be visible. Settings closer to Transparent make the overlay increasingly more see-through, allowing overlapping data to blend.

Transparency

In the Transparency section, the Transparent option allows a particular color (or colors) to be displayed transparently, making it possible to see through a layer to the layers underneath.

The Set Transparent Color... button allows the user to select the color (or multiple colors for palette-based files) to treat as transparent in the selected overlay(s) as well as save the palette for palette-based files to a color palette (.pal) file.  

The Exact to Fuzzy slider in the Transparency section controls how similar to the selected transparent color(s) that a color in the image has to be before it is also treated as transparent. The Exact side means that only exact matches on color will be treated as transparent, moving the slider towards the Fuzzy side makes progressively less similar colors be treated as transparent. This is useful for getting rid of colors in lossy formats like JPG and ECW where the colors are not exact.

Blend Mode

The Blend Mode setting controls how an overlay is blended with underlying overlays, in addition to the Translucency setting.

The Blend Mode settings allow Photoshop-style filters to be applied to overlays, resulting in often stunning results. The results from a particular set of overlays from a particular blend mode setting can often be hard to predict, so rather than try to understand what is technically happening for each blend mode it's best to just experiment with different ones until you find one that you like. The Hard Light setting seems to work well with satellite imagery overlaid on DEMs, but the others can be quite useful as well.

The Transparent option allows a particular color to be displayed transparently, making it possible to see through a layer to the layers underneath. For Example, when viewing a DRG on top of a DOQ, making the white in the DRG transparent makes it possible to see much of the DOQ underneath. Pressing the Set Transparent Color... button allows the user to select the color to treat as transparent in the selected overlay.

Resampling

The Resampling option allows the user to control how the elevation value for each displayed/export location is determined based on the values in the file.

The following resampling methods are supported:

• Nearest Neighbor - simply uses the value of the sample/pixel that a sample location is in. When resampling or reprojected an image this can result in a stair-step effect, but will maintain exactly the original color values of the source image.
• Bilinear Interpolation - determines the value of a new pixel based on a weighted average of the 4 pixels in the nearest 2 x 2 neighborhood of the pixel in the original image. The averaging has an anti-aliasing effect and therefore produces relatively smooth edges with hardly any jaggies.
• Bicubic Interpolation - a more sophisticated method that produces smoother edges than bilinear interpolation. Here, a new pixel is a bicubic function using 16 pixels in the nearest 4 x 4 neighborhood of the pixel in the original image. This is the method most commonly used by image editing software, printer drivers and many digital cameras for resampling images.
• Box Average (3x3, 4x4, 5x5, and 7x7) - the box average methods simply find the average values of the nearest 9 (for 3x3), 16 (for 4x4), 25 (for 5x5), or 49 (for 7x7) pixels and use that as the value of the sample location. These methods are very good for resampling data at lower resolutions. The lower the resolution of your export is as compared to the original, the larger "box" size you should use.
• Filter/Noise/Median (2x2, 3x3, 4x4, 5x5, 6x6 and 7x7) -  the Filter/Noise/Median methods simply find the median values of the nearest 4 (for 2x2), 9 (for 3x3), 16 (for 4x4), 25 (for 5x5), 36 (for 6x6) or 49 (for 7x7) pixels and use that as the value of the sample location. This resampling function is useful for noisy rasters, so outlier pixels do not contribute to the kernel value. Some common sources of raster noise are previous compression artifacts or irregularities of a scanned map/image.
• Box Maximum (3x3, 4x4, and 5x5) - the box maximum methods simply find the maximum value of the nearest 9 (for 3x3), 16 (for 4x4), 25 (for 5x5), or 49 (for 7x7) pixels and use that as the value of the sample location. These methods are very good for resampling elevation data at lower resolutions so that your new terrain surface has the maximum elevation value rather than the average (good for terrain avoidance). This method behaves the same as the average on raster/imagery layers. The lower the resolution of your export is as compared to the original, the larger "box" size you should use.

Shader

The Shader option allows the user to choose which elevation shader is to be used for coloring the cell values within this layer. By default, all gridded layers will share the elevation shader selected on the toolbar, but there may be certain situations where you want to color one layer differently than the others and exclude it from the loaded elevation range. One common example is a gridded layer that actually has non-elevation data.

Check the Use Global Enable/Disable Hill Shading Option to indicate that the use of hill shading on this layer should be controlled by the global option to enable or disable hill shading for all layers. The global option can be changed from the Shader Toolbar or from the Vertical Options tab on the Configuration dialog.  

When the Use Global Enable/Disable Hill Shading Option box is not checked, then use the Use Hill Shading for this Layer check box to control whether or not to use hill shading when the selected layer is displayed.  If this box is checked, the layer will have hill shading applied regardless of the current value of the global hill shading option.

If more than one elevation layer are selected, and those layers have different settings for Use Global Enable/Disable Hill Shading Option, then a light grey check will appear in the box. Any subsequent changes to the hill shading options will then be applied to all selected layers.