One of the challenges of working with Heightmap based terrain is the visual rendering of the 16-bit altitude data to standard computer 8-bit displays.
When abstracted as an image, a Heightmap is essentially a 16-bit grayscale bitmap. Unfortunately modern computers can only display an 8-bit grayscale. This poses a number of questions regarding the optimal methods of rendering the Heightmap to provide a good visual representation of the full 16-bits of altitude data.
HMES approaches this issue in a two-fold manner, with full color gradient ramps and auto-ranging color gradient ramps. A variety of gradient ramp styles are provided, including planet-like altitude simulations such as arctic, desert, and lush green worlds, where the colors can change from dark blue oceans to green forests to white snow-covered mountain peaks. While other terrain software typically supply only one method of coloring, HMES supports both full color range and auto-ranging color sets, with the appropriate style set for each specific rendered 2D or 3D view.
The HMES full color range color sets always have their darkest color starting at the 16-bit absolute altitude of 0 and their lightest color ending at the 16-bit absolute altitude of 65535. This is essentially how the standard RGB color space relates to conventional paint software, and is used in HMES when performing paint style functions such as brightness, contrast or gamma. The limitation on using this type of colorset selection for displaying Heightmaps is the fact that most Heightmap content use such as video games is commonly limited to the central 4000 to 8000 altitude range out of the 65536 range total, resulting in an image display that is typically close to monochromatic when rendered on a 3D mesh.
The HMES auto-range color sets more closely resemble the planet-like range of colors from ocean or land up to mountain peaks. The auto-range color sets also automatically scale to the current extents of the Heightmap altitude range, so the lowest Heightmap altitude is always the same ocean blue and the highest Heightmap altitude is always the same white mountain peak. This type of colorset selection is excellent for displaying 3D rendered terrain meshes, and is used in most of the HMES 3D view modes. Its limitation is that it does not work well in the 2D paint style functions, so it is typically not used in those views.
TerreSculptor HMES on an Atom 330 PC with Windows 7 displaying the auto-range desert colorset. The axis icon and grid are hidden, the water level is visible.
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