• Maxon Cinema 4D

  Applying HAIR with a density map

  Posted by Brian Murphy on April 15, 2009 at 6:09 pm

  Hey guys, I have a large relief map that spans a long distance. I am only moving a camera around a little bit in a small part of that relief map and don’t wish to apply grass to the whole relief object because of time and RAM so I have created a flat mapped texture of black with that small area designated in white and used that as a density map in my hair material. This does not work, however and seems to apply the grass to the whole relief map – I can’t find any tutorials on a situation like this so what’s going on? Do I apply it to the material or the grass object (which also lets me specify a density map)? I’ve tried both and do not get the results I desire. I can’t “project” the grass texture onto my relief map can I? Not like an ordinary material. Frustrating!

  So, in other words, I want only a small area of my entire relief map to have the grass. I have selected ALL the polygons on the relief object and created my linked selection for my hair object but applying my grayscale image of just the desired area in white to the density field in the grass material, it doesn’t work. What am I doing wrong? Should I be using the DENSITY filed for this at all?

  Thanks,
  Brian

  Brian Murphy replied 17 years, 1 month ago 2 Members · 2 Replies
• 2 Replies

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  Adam Trachtenberg

  April 15, 2009 at 10:27 pm

  First, I would restrict the hair to the polygons that you want populated. The density map essentially culls hairs that aren’t in the white areas of the map, but you still have to generate enough hairs for the entire object in order to get sufficient density in the zone you specifiy with the map.

  The texture or bitmap goes in the Hair object’s Hairs>Growth>Density slot. It’s going to use UVW mapping assigned to the object that’s growing the hair. I think the best way to go about it is to use BodyPaint to create the density map.

  Easiest way to do that is to select the BP painting layout, select the object that will be growing the hair (the plane) and then run the paint setup wizard (tools menu). Select black as the background color. When you’re done with the wizard, paint the areas where you want hair white and save the texture. Then load the texture into the hair object’s density slot. You won’t see the effect until you render.
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  Brian Murphy

  April 16, 2009 at 5:17 pm

  Thanks for the detailed explanation Adam!

  Brian

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