[fv]

I have just tried some test with displacement.
Regretfully it does work. For example, the displacement materials from the mxmgallery do not work on my SU models. All other materials work ok but with displacements in them I have a scale problem with the texture mapping. The applied mappings in SU are reduced in size in MXCL and the displacement itself becomes distored and enlarged when compared to what I see in MXED.

Any help here?

[fv]

sorry, downloaded a scaled texture from the gallery. Some people make materials or textures with a predefined scale factor for all the imagemaps.
If you place those in SU you will have some problems...

Anyhow, I got really weird wobbly displacements. Have to be careful downloading materials...

[Mihai]

Have a look in the manual about displacement, and check absolute scale for more predictable results.

[Richard]

Mate you may find that the materials have been adjusted to suit the test scene.

I think it would be great if NL introduced another option under the displacement tab to scale displacement height as a percentage of the representative tile size ie: if you have a grass texture that represents a actually area of 2mx2m a setting of 1.5% would represent 30mm of grass height!

[Mihai]

Well, how much it's tiled won't matter. If you use absolute scale, no matter the size of the geometry the material is attached to, you will get that height. So it's easier than trying to think in converting to a percentage.

[creasia]

I had problems with displacement too, and mostly on sandbox objects, but this does not work well at all. Displacement doesn't seem to like triangle shaped faces. Try recreating it with quads, or in other words make all your geometry using four sided square faces.

This made a world of a difference for me.

[Richard]

Mate I'm not having any problems with displacement on snadboxed surfaces! Remember Maxwell will I think break them down to triangles anyway! Funny though I'm not really finding speed gains breaking planes up! Though I understand I should.

I think though I need some help with displacement maps and settings I'm having to use simply put - rediculous precision settings! In fact with a roof tile material I'm trying to create I've had to use a precision of 2500 - if I select adaptive I waited nearly an hour before the render even kicked in!

Mihai is this why I'm not getting speed gains? Is precision increased as the surface is more triangulated? Meaning the more I break my surface can I lower my precision?

[Fernando Tella]

Mihai is this why I'm not getting speed gains? Is precision increased as the surface is more triangulated? Meaning the more I break my surface can I lower my precision?

That precision is really high. I'm usually moving between 30 and 150 but you have to triangulate the mesh quite a lot; but maybe that's something sketchup don't like very much.
Yes, the more you triangulate the mesh the more you can lower the precision and faster it renders.

[Richard]

Thanks mate - yeah I too thought it was high! This afternnon I ran a test with the surafce really broken up and like some previous test this time selected the adaptive option and it ran very fast.

I'd suggest the 2500 precision was required due to the size of the single plane. Once this was broken up speed came with the use of adaptive!

[Mihai]

Adaptive will try to extract every bit of detail from the displacement texture, so it's a way to see just how much detail you can get using a certain texture, and it's easier since you don't have to test manually which precision setting is ok for a certain geometry. But most times, especially if the displacement is not going to be seen in an extreme closeup, it's better to have adaptive off and manually enter a precision setting. Especially if you have a large displacement texture with lots of detail, you will get high render times.

It matters also how subdivided the geometry is to start with like Fernando pointed out. Take care also not to have very long and thin triangles in the base geometry since this can cause problems in the displacement.

For example the base plate in this image would not be so good, while the tube is ok.

http://www.thermoanalytics.com/support/ ... image5.jpg

[Richard]

Thanks for the explanation Mihai!!!

Mate the results came out that if I had my whole roof pitch as a single plane and selected adaptive the render time was rediculous and a setting of 2500 needed to get the right result.

If I segmented the roof significantly then using adaptive the render times are really quite fast - obviously then in that case the 2500 is massive overkill!

Mihai for president!!!