Frontier bump issue

sboerner · March 22, 2020, 04:14:09 PM

I noticed this some time ago and thought it might come up here, but haven't seen any specific references to it.

I'm seeing problems with displacement (bump) mapping on imported objects in recent frontier releases of Terragen. Version 4.4.45 (which I think is the most recent official release) works fine. But with later frontier versions bumps along edges, and negative bumps, seem to create ridges that cast shadows and render much darker than the rest of the object.

Has anyone else noticed this?

(Forgive the low-quality noisy renders.)

Edit to note that the rope displacement is slightly negative, all other displacements are positive.

bobbystahr · March 22, 2020, 05:05:26 PM

I've not noticed that but there's an update you don't have. I have 4.4.49..maybe that would fix it.

sboerner · March 22, 2020, 10:08:29 PM

Thanks, Bobby. I didn't realize that I'd missed a version. Just tried it, same result.

Matt · March 22, 2020, 11:11:09 PM

Can you send me an object that shows this problem? I don't have one in my test suite.

sboerner · March 22, 2020, 11:45:18 PM

I think I've figured it out. In the original file the wood shader had a small negative displacement offset, so I set that to zero. The rope shader had a negative displacement (which turned out to be unnecessary), so I made that a positive offset. The object renders fine now.

It's interesting that version 4.4.45 tolerated these negative values. But it's easy to avoid the problem by not using them, and maybe that's best practice anyway.

Happy to send a file, Matt, but maybe this was user error?

WAS · March 22, 2020, 11:47:26 PM

Maybe it's the quality of the first example but your fixed example appears to have no bump, just texture.

sboerner · March 22, 2020, 11:51:58 PM

Probably the difference in lighting (and poor quality of the first example). There's definitely a bump.

Matt · March 23, 2020, 03:02:37 PM

I'd like to see one of these objects anyway (with negative displacement). The render should be OK with bump generated from negative displacement. I've had to play whack-a-mole on bump mapping issues, and your objects seem to be an edge case I haven't seen before.

sboerner · March 23, 2020, 04:13:01 PM

OK, I'll send that as soon as I get a chance.