topic Re: Displacement - Triangulation Issue in Visualization

Displacement - Triangulation Issue

derekjackson — Thu, 11 May 2023 09:53:39 GMT

Hi,
I'm playing around with CineRender's Brick shader, and trying to get some convincing results when using it in conjunction with Displacement.

I've just done a test render and there seem to be some real oddities. The shadows between the bricks appear larger and blurred in certain areas (boxed in red). There's also a weird diagonal artefact on the first floor. The wall is one consistent element, yet the change seems to be related to window position. I can only assume it's something to do with how the wall is triangulated at render time.

Has anyone else had this? Is it a PhotoRendering setting that I've got wrong, or a bug of some sort? Any advice welcome!

Re: Displacement - Triangulation Issue

Erwin Edel — Tue, 18 Sep 2018 13:25:32 GMT

How big of a displacement are we talking? I generally start modelling anything from 10 mm up. The few times I've tried displacement the render times were rediculously long.

Re: Displacement - Triangulation Issue

derekjackson — Tue, 18 Sep 2018 13:29:47 GMT

10mm. Render took about 3 hours, so using Displacement seems plausible for the odd shot - if it looks okay!

Re: Displacement - Triangulation Issue

Erwin Edel — Tue, 18 Sep 2018 13:35:21 GMT

3 hours is too long for me

We do a lot of renders for clients and try to keep them at around 5 mins max for exteriors, where we finish things off with a bit of photoshop.

Creating a pattern in a complex profile won't take very long and the render without displacement will be fast.

I did notice some weird behaviour when I was still trying stuff out with cinerender around AC18 times to get to a mode where we are now with render times nice and fast and decent enough results.

I think the best results were with creating a morph plane with subdivision that sat on top of the actual surface. It's been a few years, so maybe someone else who is actually using this stuff can shed more light on the subject.

Re: Displacement - Triangulation Issue

derekjackson — Tue, 18 Sep 2018 13:48:15 GMT

Hmm - a morph plane would be a major hassle, given that we're still shuffling window positions around.

Shame that the Displacement shader can't be relied upon - the bits that worked look great!

Has anyone found a way around the issue via settings in the Displacement shader options?

Re: Displacement - Triangulation Issue

Erwin Edel — Tue, 18 Sep 2018 14:12:41 GMT

Thinking back this might have been sub polygon displacement.

Just had a look at the help for this: https://helpcenter.graphisoft.com/user-guide/77481/

Not overly thrilled by the results for bricks there. Edges are too rounded / soft to be believable, IMO.

Re: Displacement - Triangulation Issue

derekjackson — Wed, 19 Sep 2018 08:49:49 GMT

Well I'm trying the sub-divided Morph plane trick to see if that works. I can always up the SPD number too...

Yep, the rounded bricks don't look too good up close, but it should work well from a distance - mortar shadows relating to sun position, nice silhouettes on building edges, etc...

Re: Displacement - Triangulation Issue

Lingwisyer — Wed, 19 Sep 2018 08:52:47 GMT

If you use a Normal map instead, I do not think you get the rounded effect.

Ling.

Re: Displacement - Triangulation Issue

derekjackson — Wed, 19 Sep 2018 13:05:20 GMT

True, but you don't get the nice silhouette either...