 Refer to this excerpt from the ReadMe.txt included in the Armadillo_1_0_157.zip update:
A "probability map" is a normal Photoshop 24-bit image that defines the probability of a tree showing up at a given location on the terrain. It does NOT guarantee a tree will go there, but it CAN prevent a tree from going there. To make a Nats probability map: Create a 24-bit TGA at 1280x1280 resolution. Pure white colors yield high probability of a tree going there. Black yields zero probability a tree will go there. 128,128,128 grey = 50% probability and so on. It works just like a displacement, only brightness equates to higher probability of tree placement rather than terrain height. Once you've painted your map, rotate it 90 counter clockwise. This is dumb. There is a bug I can't fix tonight. Save the 24-bit targa in the same folder as your armadillo project, named the exact same as your base project name, with a "_prob" attached to the file. For example: You have a project named myfirst.prj Name your probability map myfirst_prob.tga Paint your prob maps BLACK everywhere you DO NOT want trees to show up ever, such as on your track. Also, paint your prob maps black everywhere you place 3D models and DO NOT want trees to show up sticking through the object.
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The info in the excerpt above is straight forward; refer to it for the basics. The explanation below was realized from mistakes I made while learning to use probability maps I hope they help you with your designs.
The 1280x1280 pixel image represents more than just the track tile. This is not made clear in the read me. While the familiar Displacement and Texture maps used in Armadillo are sized per tile the Probability map is sized for the whole MCM2 environment or universe.
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This is an example of my Starwatch Staircase Nationals Track design illustrating how the 1280x1280 pixel area is subdivided into a 5x5 grid of 256 pixel tiles. The main track tile is in the center surrounded by the perimeter tiles which are in turn surrounded by the boundary tiles. |
You may have noticed that the readme makes no mention of Stunt, Enduro, Baja, or Tag layout instructions. This is what works for me:
Use a 1536x1536 pixel image with a 6x6 pixel grid. You may already be aware that the 513x513 pixel Stunt, Enduro, Baja and Tag Displacement maps you design are used to create four tiles, rather than one, in the MCM2 environment.
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This is an example of my Starwatch Staircase Enduro Track design illustrating how the 1536x1536 pixel area is subdivided into a 6x6 grid of 256 pixel tiles. The four main track tiles are in the center surrounded by the perimeter tiles which are in turn surrounded by the boundary tiles. |
This is a to scale example of a 1536x1536 probability map I have used successfully. It is very simple but it works just like it is supposed too.
Notice that I have followed the instructions in the Readme.txt; The image is oriented 90 counter clockwise compared to the Displacement or Texture maps. |
The sharp number crunchers out there may notice that I have mentioned a 256 pixel grid while the displacement maps use numbers like 257 or 513. I believe Armadillo is set up to use a 257 pixel displacement map that is actually a 256 pixel square plus a ONE PIXEL STRIP added to the right and bottom edges. The data in the strip is tobe identical to the left and top edges respectively. This convention helps with tiling the terrains and keeping the seams smooth.
For precise placement of the tree lines trim the displacement maps to 256 pixels square when using them as reference guides. If you shrink or resize the maps from 257 to 256 the trees will seem to drift away from your reference points in some places.
Look for more info about displacement map tiling in an upcoming tutorial. |
I hope this tutorial was helpful. Please contact me with any comments or questions.
Mike McCue |
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