Flight Unlimited III high resolution terrain processing workshop

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The color rules of the high resolution levels 3, 2, 1 and 0

As mentioned in the White Papers of Looking Glass Just don't expect to plop in a big 8-bit bitmap file and have it work as a terrain texture. - is true. The simple way is valid for levels 7 down to level 3 only - just convert your bitmaps to targa files using the palette 908 and you get the map codes. From level 2 to level 0 the files are compressed and bound to the upper level - that the way to squeezes 3 texels into one byte.

As explained in the superpalette page, there are texels with 2 bit color code and with 3 bit color code. A byte has 8 bits 2+3+3 and can store the 3 texels using this coding. On the next page you will learn how tricky this simple rule is implemented.

texel             texelc23

Sergey's utilities are starting with 1 map for each level 3, 2, 1 and 0. The compress process start with level 3 an match the color of level 2 for the subpalette given from level 3. Then same procedure for level 2, with a color match of the level 1 map. Last step same as before for level 1 matching the color of the map of level 0.

My GenQuadrant tool is going another way and start with a level 0 map in Targa format. The first 3 steps are going in a bottom up direction. step 1 generate a level 1 map by choosing the best fit for a subpalette including the 4 neighborhood texels and storing the subpalette code as level 1 texel. Same is done for level 2 and level 3. now we have all maps and the level 2 - level 3 assignments are all valid - but during the up process there are some texels in the level 1 that have changed to fit in the level 2 palette and that will also affect the level 0. In the last steps, starting with level 2, the level 1 is matched to the predefined subpalette in level 2 and then makes the last color modification to the level 0 using the predefined new subpalette codes of level 1. After that the color is valid for the full chain.

The color dependency of the subpalette sharing affects 64 level 0 texels, 16 level 1 texels, 4 texels of level 2 and 1 texel of level 3 as shown in the next pictures.

texel11 texel12 texel13 texel14
texel21 texel22 texel23 texel24
texel31 texel32 texel33 texel34
texel41 texel42 texel43 texel44

Information: André Meystre
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