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View Full Version : Displacement maps: Need a bit of elaboration

Lestat
06-22-2003, 09:43 PM
I have this problem with displacement maps - i don't know if there's a setting i'm missing, or if they just won't do what i want them to.

Basically i need them to easily add some cracks to a road. The added geometry isn't a huge problem, i only need a single very high res image, but i need it to look good, so bumpmaps won't work well enough.

My problem is, no matter how i seem to construct the displacement map, it won't make a crack - use a black line on transparent makes a little bump, use a white line on transparent makes a big bump, use a black line on white, oh boy, huge bump with a small indent etc.

Basically i want a 1000x500 map with a crack painted on it, applied to a planar surface (well, almost) using a planar map. And i want it to indent on the surface. How? I'm missing something i think. Could anyone try to explain how the displacement map is interpreted by that channel? And is there a specific setting in the displacement approximator that works better than others? (Using default now).

Thanks in advance. :)

L.
digital NUT
06-23-2003, 04:19 AM
There should be some button within the settings that lets you choose how strong the displacment is. If that's not the problem, I don't know what is ( you say you applied the map to the displacement modifier already, correct?). And also, make sure the surface you are mapping has enough faces to support the picture. Anymore questions, ask away.:thumbsup:
Ian Jones
06-23-2003, 05:10 AM
usually with maps:

grey= no effect
black= negative effect
white= positive effect

So you probably need a grey disp map with black crack lines. Crank the displacement amount to a higehr value if you need more depth.
Ian Jones
06-23-2003, 05:20 AM
Or just spin the map around till its upside down?! :)
Lestat
06-23-2003, 11:19 AM
Originally posted by Ian Jones
usually with maps:

grey= no effect
black= negative effect
white= positive effect

So you probably need a grey disp map with black crack lines. Crank the displacement amount to a higehr value if you need more depth.
I tried using 50% grey, and still the grey part of the map wasn't level with the surface i was displacing. I'll try doing a quick render of the problem later and post, it's probably easier than explaining. (A picture and a thousand words and all).

L.
Marcel
06-23-2003, 02:20 PM
The strength of the displacement map is set my the percentage (just like the diffuse map for example). Only with the displacement map 100% strength means that the displacement is as big as the bounding box of the object, 50% means half the bounding box size, etc etc.

Since it is at 30% at default, you should definitely see the effect of the displacement map.

Have you turned on the editable mesh->surface properties->subdivisions displacement option? That will subdivide the mesh at rendertime to the correct amount of detail. I can image that with the subdivisions the mesh does not have enough detail to make a small crack.
ninjacore
06-23-2003, 02:45 PM
heres the best way i've found.

make a plane whatever size you need. crank the segements up to 100x100 (it can vary to suit needs) and put the Plane Density spinner up, say a value of 5. right underneath this, you will see how many faces the plane will have. these wont be displayed until rendertime.( dont go over a million faces)

after that, slap on your displace modifier, apply your greyscale map, and adjust the Strengh and decay spinners to suit your needs.

hope that helps!

oh yeah, u can also add another displace modifier above the first one to add extra detail. and remember, if your mesh needs more or less faces, u can always go back to the original plane and adjust. better than having to do edit poly conversion!
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