WWII Jeep tread disappearing in Iray.

Petercat

When I render the WWII Jeep in 3DL, I get this:

But when I render it in Iray, I get this:

What happened to the tires? Where did the tread go, and how can I get it back? Or am I stuck with 3DL for scenes with the Jeep in them?

fixmypcmike

Check the Surfaces pane for how the treads are done -- possibly displacement that isn't being picked up in Iray?

Petercat

Fixmypcmike said:

Check the Surfaces pane for how the treads are done -- possibly displacement that isn't being picked up in Iray?

It's showing:

Displacement Strength 50%

Minimum displacement 0.00

Maximum Displacement 1.00

What should I try? I'm not at all experienced with using displacement, but need to learn. Thank you.

Petercat

Okay, I set DS to 200% and Max D to 4.00 and things got ugly:

Might be useful on a monster truck, but not what I was going for...

Oso3D

Make sure the Displacement SubD is at least 3.

3DL displacement goes on a 'per pixel' basis, and adjusts based on the surface very nicely.

Iray displacement is based on the mesh and pushes based on each vertex. It is incredibly sensitive, thus, to mesh density. Displacement subdivision essentially adds complexity just for the purpose of displacement (I think because it may be less hard on rendering than actual subdivision? Not sure)

 

Petercat

timmins.william said:

Make sure the Displacement SubD is at least 3.

3DL displacement goes on a 'per pixel' basis, and adjusts based on the surface very nicely.

Iray displacement is based on the mesh and pushes based on each vertex. It is incredibly sensitive, thus, to mesh density. Displacement subdivision essentially adds complexity just for the purpose of displacement (I think because it may be less hard on rendering than actual subdivision? Not sure)

 

Where do I find the Displacement SubD setting?

scorpio

In the surfaces tab underneath the displacement settings.

Petercat

scorpio said:

In the surfaces tab underneath the displacement settings.

Do you mean surfaces: editor: displacement? All I see are displacement strength, minimum displacement, and maximum displacement.

Oso3D

Try setting displacement strength to 0 and back to whatever it is? Sometimes when converting it misses subd.
 It should be right after maximum displacement.

barbult

Have you converted the surface to Iray Uber shader? That will be necessary to see the SubD Displacement Level. To convert the surface, select the Jeep in the Scene pane. Then go to the Surfaces pane, Editor tab and expand the Jeep WW2 to see all the surfaces that make it up. You will see rubber as one of the surfaces. Select it (or select all of the surfaces, even better). Then go to the Surfaces pane, Presets tab and drill down to Shaders>Iray>Uber and double click on the !Iray Uber Base shader. Now go back to the Surfaces,Editor tab and be sure that only the rubber surfaces is selected. Scroll down through the channels until you come to SubD Displacement Level. There you can change it from 0 to 3, as Will suggested. Don't go too high on that value! it will slow your render down dramatically. Even with the SubD Displacement Level set to 3, the tread is not going to look as nice as the 3Delight render. Displacement in Iray just works differently and not very well.

The attached file uses Displacement Strength .5, Minimum Displacement 0, Maximum displacement 1.00, SubD Displacement Level 3. It looks poor, but my computer can't take any higher level of SubD for this model.

Oso3D

Oh jeez, I had just assumed conversion to Iray for second render. Yeah. What Barbult said.

 

barbult

One thing you might want to consider is converting the displacement map to a normal map. Then delete the displacement map from the rubber surface and insert your converted normal map in to the rubber surface Normal Map channel. It will render much faster, use much less memory and look better in my opinion. It will not be true displacement, though.

You can get a tool to convert your displacement map to a normal map here.

 

barbult

Here is my best attempt. It uses both Displacement and Normal Map. The Displacement gives it some true geometry offset and the Normal Map gives it a better level of detail.

Displacement Strength .5, Minimum Displacement 0, Maximum displacement 1.00, SubD Displacement Level 3

Normal Map 1.00 (using map converted with Photoshop using Nvidia tool)

You can experiment with different min/max displacement levels, but be very careful to not increase the subD too high.

Richard Haseltine

You could use the Geometry Editor to select, hide and delete everything but the tyres on one copy of the jeep, hide (or delete) the tyrres on the original, and apply the SubD to only the tyres - that willa llow you to use a higher level as you aren't dividing everything else. But normals, or bump, plus a limited amount of displacement is probably better - it's one of the annoyances of Iray.

Petercat

barbult said:

Have you converted the surface to Iray Uber shader? That will be necessary to see the SubD Displacement Level. To convert the surface, select the Jeep in the Scene pane. Then go to the Surfaces pane, Editor tab and expand the Jeep WW2 to see all the surfaces that make it up. You will see rubber as one of the surfaces. Select it (or select all of the surfaces, even better). Then go to the Surfaces pane, Presets tab and drill down to Shaders>Iray>Uber and double click on the !Iray Uber Base shader. Now go back to the Surfaces,Editor tab and be sure that only the rubber surfaces is selected. Scroll down through the channels until you come to SubD Displacement Level. There you can change it from 0 to 3, as Will suggested. Don't go too high on that value! it will slow your render down dramatically. Even with the SubD Displacement Level set to 3, the tread is not going to look as nice as the 3Delight render. Displacement in Iray just works differently and not very well.

 

 

No, I hadn't. I just did, though, and got the results you did. But with Dstrength at .50 and MaxD at 2.00, with SubD at 4.0, I got this:

 

So I'm getting closer! Thanks, everyone!

 

Petercat

Maybe I should just bite the bullet and buy "Warehouse Building with Items"... But I like this Jeep better!

And now that you all have pointed me in the right direction, I actually like the tire tread better, too.