Micropoly Displacement and BVH Issues

General discussion about Cycles 4D.
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ButterGroove
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Joined: Sat Jan 06, 2018 8:03 pm

Micropoly Displacement and BVH Issues

Post by ButterGroove » Tue Feb 13, 2018 5:24 pm

Hey guys, I'm following up from this thread: viewtopic.php?f=3&t=742

I ran a bunch of tests and realized that the CUDA out of memory issues are stemming from micropoly displacement. I've attached a zip file with scene and textures so you guys can see if you are running into similar issues. I think I've narrowed the problem down to the "Dicing Scale" option in the cyObject tag. I understand that lowering this value will lead to finer and more micro displacement, even when applied to a low poly object. I had tried increasing the number of polys in my objects and increasing the resolution of my Dmap but that didn't seem to lead to much more fidelity and micro details. I'm using an 8k Dmap but lowered the resolution to 2k. I've also got a 4k HDR background image which is set to only 1K.

So basically, if I lower the Dicing Scale option too much, I get the CUDA out of memory issues. The lowest I've been able to set it to is 0.25 or so for any of the objects that it is applied to. On top of that, when I have the RTP window running, navigating in my main C4D window is really slow. I can temporarily increase the Dicing Scale to alleviate this, which then of course makes the displacements look really ugly. I'm trying to find the right balance between quality of micro displacements without bogging down renders and navigating too much, and I'm really struggling. I don't understand why this is such an issue when I'm running a machine with 2 GTX 1080s and a GTX 980Ti with the latest Nvidia drivers, 32GB memory, and an 8-core i7 processor.

Another big issue I'm having is getting things to update correctly in the RTP window and during rendering to the PV. I don't really understand the BVH options in Cycles, but that seems to be part of the issue as well. It seems that if I set BVH Type to "Dynamic" in the render settings, things update faster in the RTP window, but slower in the PV. If I set Type back to "Static" then renders in PV are a bit faster. I'm totally baffled by the "Use Spatial Splits" and "BVH Time Steps" options. I've messed around with them but not sure what if any impact they are having. If someone could explain these features that would be really helpful, as the Cycles Help file doesn't really cover them well. Do they have any impact on rendering of Dmaps?

ButterGroove
Posts: 12
Joined: Sat Jan 06, 2018 8:03 pm

Re: Micropoly Displacement and BVH Issues

Post by ButterGroove » Tue Feb 13, 2018 5:27 pm

I'm having trouble attaching the scene files. Does the forum not accept .rar files? File size is about 15 mb. When I go to attach the file it uploads just fine, but doesn't seem to actually be attached to the post...

ButterGroove
Posts: 12
Joined: Sat Jan 06, 2018 8:03 pm

Re: Micropoly Displacement and BVH Issues

Post by ButterGroove » Tue Feb 13, 2018 5:28 pm

File can also be accessed via this link if attaching isn't going to work: https://drive.google.com/file/d/1uORLWS ... sp=sharing

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Mohamed Sakr
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Re: Micropoly Displacement and BVH Issues

Post by Mohamed Sakr » Tue Feb 13, 2018 5:42 pm

0.25 in Micropoly is so much!! leads to millions of polygons.
I usually set it to 1.
and displacement map size won't make a big difference (just the map size memory allocation).
so the big impact is from the Micropoly size that you choose, if it is 0.25 it will be out of memory most likely.
Micropoly is not a feature for modelling base details, it is a feature for fining base details (like a low poly character of 20k polygons, and you use Micropoly to make it 1 Million polys, this will work).
I didn't check the file yet.

ButterGroove
Posts: 12
Joined: Sat Jan 06, 2018 8:03 pm

Re: Micropoly Displacement and BVH Issues

Post by ButterGroove » Tue Feb 13, 2018 6:02 pm

Mohamed Sakr wrote:
Tue Feb 13, 2018 5:42 pm
0.25 in Micropoly is so much!! leads to millions of polygons.
I usually set it to 1.
and displacement map size won't make a big difference (just the map size memory allocation).
so the big impact is from the Micropoly size that you choose, if it is 0.25 it will be out of memory most likely.
Micropoly is not a feature for modelling base details, it is a feature for fining base details (like a low poly character of 20k polygons, and you use Micropoly to make it 1 Million polys, this will work).
I didn't check the file yet.
I need that high level of detail because I'm trying to build a techie looking microscape while using simple polygonal objects. I'm running further tests and now I'm getting this error: "CUDA error at cuCtxCreate: Illegal address" even though I stripped the scene down to just the plane object and even set Dicing Scale back to 1. It's only working on the CPU now. Ugh >_<

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Mohamed Sakr
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Re: Micropoly Displacement and BVH Issues

Post by Mohamed Sakr » Tue Feb 13, 2018 6:30 pm

ButterGroove wrote:
Tue Feb 13, 2018 6:02 pm
Mohamed Sakr wrote:
Tue Feb 13, 2018 5:42 pm
0.25 in Micropoly is so much!! leads to millions of polygons.
I usually set it to 1.
and displacement map size won't make a big difference (just the map size memory allocation).
so the big impact is from the Micropoly size that you choose, if it is 0.25 it will be out of memory most likely.
Micropoly is not a feature for modelling base details, it is a feature for fining base details (like a low poly character of 20k polygons, and you use Micropoly to make it 1 Million polys, this will work).
I didn't check the file yet.
I need that high level of detail because I'm trying to build a techie looking microscape while using simple polygonal objects. I'm running further tests and now I'm getting this error: "CUDA error at cuCtxCreate: Illegal address" even though I stripped the scene down to just the plane object and even set Dicing Scale back to 1. It's only working on the CPU now. Ugh >_<
does restarting c4d (or pc) solve this?

ButterGroove
Posts: 12
Joined: Sat Jan 06, 2018 8:03 pm

Re: Micropoly Displacement and BVH Issues

Post by ButterGroove » Tue Feb 13, 2018 6:58 pm

Yes restarting C4D fixes the error but it comes back in some form or another after some time. Only seems to be an issue with the RTP window. I just got a "CUDA error at cuCtxCreate: Launch failed" Seems to be fine when rendering to PV but the whole point of a render engine like Cycles is to be able to design with the RTP window updating in real-time. I can switch to CPU and RTP works but it is much slower than on CUDA (when CUDA is working). Really frustrating here. Octane is so much faster when it comes to displacement maps but I specifically got Cycles for the Xparticles integration which Octane is lacking in. Not sure what do when I need to make use of micropoly displacement with Xparticles...

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Mohamed Sakr
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Re: Micropoly Displacement and BVH Issues

Post by Mohamed Sakr » Tue Feb 13, 2018 11:12 pm

ButterGroove wrote:
Tue Feb 13, 2018 6:58 pm
Yes restarting C4D fixes the error but it comes back in some form or another after some time. Only seems to be an issue with the RTP window. I just got a "CUDA error at cuCtxCreate: Launch failed" Seems to be fine when rendering to PV but the whole point of a render engine like Cycles is to be able to design with the RTP window updating in real-time. I can switch to CPU and RTP works but it is much slower than on CUDA (when CUDA is working). Really frustrating here. Octane is so much faster when it comes to displacement maps but I specifically got Cycles for the Xparticles integration which Octane is lacking in. Not sure what do when I need to make use of micropoly displacement with Xparticles...
RTP uses more memory (because it is a single large tile instead of small tiles like in picture viewer).
so if you make RTP smaller that will help (may be by using the render region in the RTP).

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