correct geometry for vray displacement?

[chow choppe]

hi everyone

 

whats the correct geometry for using a diaplcement map

when i put it to plane the edges lift up from ground

and if i use box for grass all the faces get vray displacment separately and they get split up at the edges.

 

do i need to unwrap the grass object?

 

whats the right way?

[Thablanch]

The edge is displaced.. so the modifier does the job ok.. The map used for the displacement should be black on the edges, so the geometry can stay on the ground.. If it is grey or white, the color on the edge is getting displaced, and the thing goes up.

 

For edges on a box, lets sat, use a smooth modifier prior to the displace, this will keep the edges together.

[Ricardo Eloy]

It also deppends on what type of displacement you're using. When using 3D, you can check the Keep Continuity option to try to avoid that. You can also apply a mesh smooth mod, but you have to keep in mind that the displacement effect follows the normals, so it's expected to blow the edges where the angle between the faces is too high.

[chow choppe]

Thablanch

 

So u mean every time i have to uvw unwrap my all grass areas and make a texture in pshop

 

because right now i am just tiling a displacement map on my grass object using the UVW's.

 

or am i understanding something wrong here

 

thanks

[Nic H]

post some pics of what you are trying to do

but generally try to keep reasonable size quads for displacement, no skinny triangles or weird shaped faces.

Edited June 12, 2009 by nicnic

[Thablanch]

Tile a map is ok, all I'm saying is that a non-black pixel will get the geometry displaced, so, an edge can go up because of a map...mabee you need a concrete trim of some kind, where the grass, not to see the edges.

[Dave Buchhofer]

displace 40mm, shift -40mm?

[Stephen Thomas]

With displacement any part of the map with 50% grey will stay where it is. What you could do is do a screen grab of your grass areas and then paint the edges with a soft brush in photoshop to make a quick mask. Then use the mask in a mix map to blend between your original displacement map and a 50% grey colour. You'll need to assign a seperate uvw map for the mask but you'll have better control of how your displacement height falls off towards the edges using this method.