slower than molasses

[glorybound]

I have a scene that is rendering out beautifully, however, it is slower than molasses. The roof is displaced, so are the shakes, siding, and stone. If I globally disable displacement, the rendering time drops to around 45 minutes. I am following all the rules to speed up displacement, so it is what it is. My question is, are you guys modeling siding, shakes, and roof? Or, are you just not displacing things? I understand when people talk about fast render times. which I can get also, if I didn't use displacement.



What initiated this post is a discussion I had with another V-Ray guy, earlier this morning. He asked me what a good exterior render time is for me, and I said I am happy with 4-5 hours, per still. He said that if his render times, for an exterior was more than 45 minutes, something would be really wrong in his scene. After further discussion, I found out that he doesn't displace things. His siding would be a bitmap with lines on it, same with his shakes, and his roofs are just bitmaps. I like the siding to have depth, which adds a ton of detail along trim and other geometry. The shakes look much better displaced for the same reason and roofs with random material id make for a seamless roof.

Is it worth the time for the extra subtle detail? Is so, is it best to model everything and avoid displacement? Is there anything out there that models the siding and shakes? I know I could rotate walls, use multi-floor and rotate them back, but that's a pain. I know there are plugins for roofs, however, I haven't found them to be very fast to use.

Yes, the estimated time on the above scene is 15 hours and 45 minutes!!!

[Morne]

Jip, I feel your pain. I'm going through the EXACT same issue at the moment. Bump mapping SUCK for siding and roof. Displacement is the only way, but it takes forever! A modeled siding wall will render 1000 times faster, but yes try and find a way to do it fast with a wall that has different sized windows, nevermind the gable bit, multi story building etc. Modeling the siding sure will be a huge pain. Hmm I wonder if railclone has an easy option here, I'll check with Paul and report back here
Also, I wonder how VRayNormalMaps would perform. That's basically a fancy bump map, but at least it looks 3D. I wonder if it will be enough for siding or we'd still fall back on displacement

[glorybound]

I thought of Rail Clone, too. Let us know what you find out. I think I looked down that path before and came up empty, but I might be wrong.

[vlado]

If you are using the 3D displacement mode, you can turn on the "static geometry" option and it will be quite a bit faster.

If you are using 2D displacement, you can try reducing the "precision" parameter from 8 to 1. I hope to do some more things about it in future builds.

Best regards,
Vlado

[Morne]

If you are using the 3D displacement mode, you can turn on the "static geometry" option and it will be quite a bit faster.

If you are using 2D displacement, you can try reducing the "precision" parameter from 8 to 1. I hope to do some more things about it in future builds.

Best regards,
Vlado

For the roofs I use 2D and it's pretty fast. If I use that on my walls, the walls go invisible for some reason so I use 3D on the walls. The thing is with 3D, I have to set the edge length very small to get any kind of good result and that is where things start to fall over. Hope you don't mind me chiming in Bobby, I think we're having pretty much the same issue with this one?

[Deflaminis]

Does it have to be displacement? Railclone is awesome but expensive, what about http://www.avizstudio.com/tools/atiles/ You could replace the Atiles with custom geo from what I understand. Too basic?

[flino2004]

I model the siding...I haven't tried yet modifying the geometry with a greyscale map for stone and shingles.

[vlado]

If I use that on my walls, the walls go invisible for some reason so I use 3D on the walls.

That doesn't sound right at all; can you attach a scene with just some part of the wall so that we can take a look?

Best regards,
Vlado

[glorybound]

Also, here is my VraySampleRate, so I am optimizing like I should. I can't try anything now, because my machine is chomping away



Morne, take it away, if you want. We seem to have the same need for faster displacement. I do have "static geometry" checked, but I haven't tried "precision" parameter from 8 to 1. I tried Avizstudio, but it was cumbersome, at least it was several years ago. Or, at least, not as easy as the "Displacement Roof Surfaces" script.

[jacksc02]

Model as much as you can.
I used to displace things like wall and floor tiles but in the end it is so much quicker to model.

[glorybound]

I stopped the render, because I wanted to tweak something in the scene, so I set my 2D displacement to precision 1 while I was in there. Yes, it does seem to render faster without any change in displacement quality. It looks like it's going fast enough to turn my DOF back on, which always looks better V-Ray.

[vlado]

OK, good to know.

Best regards,
Vlado

[Morne]

Paul sent me this so far:

Apparently same type of thing will work for siding

[glorybound]

Awesome. Thanks for looking into this.

[Paul Roberts]

Hi!

Morne kindly asked me comment here about RailClone so here goes....

RailClone has the ability to generate 2d arrays based on a clipping spline. As well as defining the size and shape of the array any splines inside the boundary will cut holes thought the geometry. This could be used quite easily to quickly populate facades or roofs. Also because RailClone instances any geometry that isn't sliced, it should render very efficiently too.

Rather than explain I've recorded a short video, no audio though I'm afraid. The first part explains the basic technique using clipping splines extracted from the source geometry, the second part show a script to speed up the process. I should mention the script is just something I made for personal use and released on the forum, it's not an official part of RailClone. We actually have plans to make applying styles to surfaces like this much simpler in upcoming versions. We want them to remain linked to the surface so they're fully interactive and with no need for extra scripts. If you have any ideas you'd like to contribute to this, they'd be welcome.

As you can see this technique works best for planar surfaces, for anything that's curved a different approach could be taken that uses a spline to define the curved path of the wall, and a clipping spline just to cut holes for windows, doors etc. I've help users in the past to create eyebrow dormers in roofs so unusual curves are possible. Something else I should mention is that at present clipped geometry is not automatically capped. We did implement this but due to some limitations of max's SDK we couldn't satisfactorily UVW map the capped polygons so it's removed until we can fix that issue. You could of course convert the RC object to regular instances or an editable mesh and fix the problem that way.

The techniques show in the video are compatible with the free lite version of RailClone so if you wanted to test it out, please feel free.

I hope that helps, please let me know if you have any questions.

Cheers,

Paul

P.S There's also a nice tutorial on creating Slate Roofs created by one of users using a slightly different technique that may be of interest. You can read it here: http://www.vizioen.be/blog/2015/2/8/...te-roof-part-i. There's also a chapter in our Next steps with RailClone guide on Clipping Splines if you fancy a read!