Rendering small scale scenes

[JuhaHo]

I'm working on a product visualization. For some reason I get very messy rendering results. V-Ray clipper isn't working either. I believe the tiny scale of my scene is causing the problems. This somewhat complex product is less than one millimeter in size. Obvious thing to try would be scaling the scene up. Does V-Ray have any parameters, that would help without scaling?

[fixeighted]

Hmm...I just tried this with a tiny teapot of 0.005mm radius. I haven't worked out how to get it to display in the viewport at that scale using a camera or in persective mode (with mm set in both settings) but
as far far as rendering goes there is no problem, apart from adaptive dome giving obvious block artifacts.
With a 1mm cube there are no issues here at all, so you should be ok with the correct scene settings.

EDIT: Clipper also works ok here with those settings.
EDIT: Silly me...of course you need to adjust viewport clipping at that scale also.

[JuhaHo]

Thanks fixeighted,

Here's a comparison of rendering and a viewport screenshots. The corner does not render correctly. Is this a lightning or maybe a renderer setting? The size of this spot is much less than 1/10 mm (or unit). Rescaling the scene didn't change anything.

[fixeighted]

Not sure what I'm looking at tbh...can you share a stripped scene with just a part maybe, with your lights?

[JuhaHo]

I tested with teapot,and didn't notice any problems there. Too bad the customer is not manufacturing teapots.I tested with different lightning too, but nothing helped. Any ideas?

[fixeighted]

To be honest I can't really be sure what the object is and so what might cause it. It looks like a bevel on a cylinder, so it could be the geometry is not right somehow. Or something else entirely....
Without more info you probably need to send it to support, to cover NDA issues here

[JuhaHo]

I tested the geometry with built in Max default Arnold renderer, and there's no problem. I used Max default lights and see no Artefacts there. On both cases I used max physical camera So it must be V-Ray or V-Ray light issue. I wonder what parameters I should check.

[fixeighted]

That doesn't unfortunately identify any bad geometry, as other renderers will render bad stuff quite happily, whilst Vray will not. As in this post a while back https://forums.chaosgroup.com/forum/...em-please-help
Your object could have a simlar thing going on - easily fixed with the same technique. I hope that helps

[Buck]

I'm working on a product visualization. For some reason I get very messy rendering results. V-Ray clipper isn't working either. I believe the tiny scale of my scene is causing the problems. This somewhat complex product is less than one millimeter in size. Obvious thing to try would be scaling the scene up. Does V-Ray have any parameters, that would help without scaling?

This is what I would do. I think it would make your life a lot easier.

On a few projects in the past, I've had to work with scenes that were extremely large and very very far away from the world origin. So large that even in the viewport and in animations (this was Maya, but probably applies to other software too), when objects or cameras got way way far away from the origin things would start to jitter around due to precision error of the enormous size of the numbers. Even if the camera and the object you were viewing were next to each other, just being that far away from zero caused problems. Plus, working with those giant numbers was difficult, having to stretch your interface out just to see how many zeros or commas were in the numbers. Our solution wasn't to scale the scene down, but to shift everything so that the camera and objects were closer to world zero. That fixed the problems. Scaling would have worked too, but we opted to move instead of scale.

If your scene is that small, I would scale up by a factor of 10, or even 100 or 1000, and move on.

[JuhaHo]

That doesn't unfortunately identify any bad geometry, as other renderers will render bad stuff quite happily, whilst Vray will not. As in this post a while back https://forums.chaosgroup.com/forum/...em-please-help
Your object could have a simlar thing going on - easily fixed with the same technique. I hope that helps

This might be the case. I originally imported the Step file by using Polytrans, but gave up because the geometry was a bit too coarse. Then switched to built in Max ATF importer. The geometry looked much better in viewport, but then I got artefacts as described. I moved back to Polytrans inport and no artefacts there, however the coarseness of the mesh is visible.

[fixeighted]

It'll need to be exported with higher tessellation is all - sounds like they gave you a viewport resolution version rather than the hi-res one.
And whoever is exporting it needs to make sure that they join all the surfaces etc., to prevent these errors
and make it generally nicer to work with, i.e. less for you to potentially fix
I didn't even know Polytrans was still in existence...not used it for years so can't help with that - but you shouldn't need it, as Max can import step files.
If you get stuck then I can most likely sort it out but that of course means sharing the model - totally secure this end but I understand any reluctance

[JuhaHo]

Thanks again,

I use Polytrans almost daily, have been using since mid 90's. Sometimes I even Fix my corrupted Max meshes there. I also use the PT polygon reduction tools of it a lot. In this case I used most dense settings for meshing, but still got too few polygons.

I have not yet tested Polytrans mesh healing tools for built in Max imported geometry.

[fixeighted]

You could check out this https://www.npowersoftware.com/NewPo...oOverview.html as an alternative, which will allow you to have basically the same level of control in the model as in the original software but within Max.

[JuhaHo]

A little follow up. I managed to do better tessellation by using Polytrans import. Rendering the same model, I didn't get the artefacts. So it seems Max built in importer was the source for the rendering problems.

[fixeighted]

That's a good result then, I'm glad.
I remembered that Max's import module for these wasn't good - haven't tried in a while.
Anyway, problem solved