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Let's use a Europe file of the GTOPO 30 arc second data set: "W020N90".
Cut a 2° by 2° sample, northwest corner at 2°W, 45°N.
| Dialog "Calculate/Import Filters/Binary DEMs..." | Result: "dem1.tga" |
|---|---|
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"dem1.tga" is the file TruFlite needs to create 3D perspectives of the terrain.
Each pixel represents an integer number containing the elevation value. In the above import dialog we specified z Scale: 256. The data source file "W020N90.DEM" contains elevation values in meters. Each value is then multiplied by 256 and stored as a colored pixel in "dem1.tga".
Here are some samples for how TruFlite's TGA files store the elevation values:
| Elevation | Red | Green | Blue | Color |
|---|---|---|---|---|
| 0 | 0 | 0 | 0 |  |
| 1 | 0 | 0 | 1 |  |
| 255 | 0 | 0 | 255 |  |
| 256 | 0 | 1 | 0 |  |
| 512 | 0 | 2 | 0 |  |
| 24000 | 0 | 93 | 192 |  |
| 1000000 | 15 | 66 | 64 |  |
| -1 | 255 | 255 | 255 |  |
| -24000 | 255 | 162 | 64 |  |
Our file "dem1.tga" always has Blue = zero because all elevation values are multiples of 256.
Let's use this file as the only input file for "scene1.trf", our first step.
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11/10/23.
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