Puddle map is controlled by Alpha Channel (opacity) of "Details Map" (roadDetailsMap, rdt, also this 397 guide). There are a few ways to do it with free/opensource software. In Blender, you can select all road mesh, and add a new UV channel to each of the road materials, then create a new texture & UV map (with all selected road mesh as a whole) in this UV channel, then paint puddles on this texture (puddles are the transparent part of the texture, you can also take reference from LochDrummond's rdt dds file). Once done, export (***_rdt.tga > MapConverter > ***_rdt.dds, also all the new *.gmt with new UV map) & loading track in devmode. Then open material editor, and assign ***_rdt.dds to Road Details Map, change UV channel to one of the channel that you added in Blender (depends on order, could be UV_B, UV_C, or UV_D). Then you can test wet effect with weather panel. Also another slight easier way to make puddles without having to map extra UV & texture. You can just create a black Road Details Map texture (size based on main road texture) and paint (transparent) puddles directly on it, then export and assign in material editor using UV_A channel (same as main road texture). If you do it right, it will look just as good as the other method. -------------------------- Edit: Steps to create Road detail map in blender: The idea is to create & map a single new UV map for all racesurface objects on UV channel 2, 3, or 4, so that this new texture covers the whole track surface. 1. Select all racesurface objects. 2. Switch to UV mode (top tab UV editing), then hit "a" hotkey to select all mesh. 3. On Left side, select one of the unused UV channel 2 or 3 or 4 (either one, or any other names that is not main channel). If there is only one channel, then you will have to create an extra one (then you can select the newly created UV channel). If there are several racesurface objects, then you will have to repeat this step for all of the objects one by one (or first merge all racesurface objects into one object). 4. On Left side, click Menu > Image > New, set texture size 4096 or bigger, then click ok. Now you have a new black texture ready to be mapped. 5. On Right side, switching to top down view by "num 7" hotkey on keyboard, then hold Left-shift & press down middle mouse to move the view just enough to cover the whole mesh. 6. Make sure it is still in top down view, Now on Right side top menu, click UV > Project from View (bounds). 7. Now you can see that Left side view has the whole mesh mapped to the black texture, you may also want to slightly resize the UV frame smaller than the canvas (left side). It is a good idea to save now (backup 1st). 8. Next, switch to "Texture Paint" mode(top tab), then paint transparent puddle on this black texture according to the mesh's wire frame. 9. When all done, save the image by click Menu > Image > Save (or Save as), and convert to DDS using MapConverter. 10. Last, make sure you have saved & exported all the modified racesurface objects to GMT for game to use, those objects now carriy the new Road detail map texture UV channel info. Then you can test & adjust Road detail map in material editor.