## Settings

| The "Settings" dialog controls the following parameters: The size of the quadrangle to download (1 degree, 0.5 and 0.25 degrees) Substitute Z = 0 values: In places, the Shuttle Radar Topography (SRTM) mission yielded no data. Very small areas have been corrected by NASA and USGS using interpolation, but larger areas (more than approx. 16 contiguous pixels) have to be fixed by the client application. In the latter case, interpolation might introduce a considerable error in altitude, but keeping Z = 0 values will leave unnatural pits in the terrain. Align quad to grid: If checked, then the grid boundaries are rounded to the nearest quad size multiple. If not checked, then the given address will be centered in the texture. Note that the given address may not show up in the center of the TruFlite-rendered 3D image: it may be shifted vertically, depending on the elevation at that point. Remove intermediate files: Keep this selected all the time unless you encounter problems or wish to document the image generation steps. Use waypoints: if checked, select a waypoint list file using the Browse... button. A waypoint list file contains waypoints to be painted on the terrain. The image to the left shows such a waypoint list: the red line. Note: When this help file was designed, the final look of the waypoints on the terrain has not yet been determined. In future releases, color and thickness may change without notice. Output file names from coordinates: if checked, then the output file names contain the coordinates of the top left (northwest) quadrangle corner. Line thickness: the thickness of the waypoint line, in pixels. Z Scale: a default of 0.02 is set. HTTP Timeout: The number of seconds the program will wait for a server response from a request before giving up. Increase this if you receive frequent timeout error messages.

TIGER Tiles explanation: The U.S. Bureau of the Census is the data supplier for the texture data: roads, rivers, etc. One download covers 1200 by 1200 pixels. Since a one degree quadrangle of the elevation data (SRTM) covers 3600 by 3600 pixels and is therefore considerably larger, you have the choice to adapt the size and the resolution of the TIGER texture data to the SRTM data.

If using 1 tile, the texture file size and resolution is small. If using 3 by 3 tiles, the texture file is larger, resulting in a higher resolution. Note, however, that all line drawings will appear thinner and all text will appear smaller in the 3 by 3 tiles mode: to match the elevation file, the 3 by 3 texture will be downscaled.

> 1 tile, original size | 3 by 3 tiles, original size
> --- | ---