Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: Correntes on 2016-11-16, 18:25:35

Title: crystal rendering slow
Post by: Correntes on 2016-11-16, 18:25:35

Hi guys,

I'm using corona final built (trial).
Default render settings.

I'm trying to render a simple scene:

an office interior Hdri on corona environment and a quartz crystal  on top of a white table.
The crystal material is a gradient map on refraction and a bump map. thin (no refraction) and caustics unchecked.

The problem, is slow as hell...


Can someone help me ?

Title: Re: crystal rendering slow
Post by: romullus on 2016-11-16, 20:09:25

Can you attach your material screenshot and render you've got? I can't imagine you can get acceptable result when rendering gemstone without refraction.

Title: Re: crystal rendering slow
Post by: Correntes on 2016-11-17, 12:17:07

I think you misunderstood me.

The options  *thin (no refraction) and *caustics are unchecked

Title: Re: crystal rendering slow
Post by: maru on 2016-11-17, 12:50:51

There is some slowdown expected when rendering refractions, which take a lot of screen space. It gets worse if the geometry is complex. Unfortunately I am afraid that this cannot be easily solved right now, but we are interested in optimizing Corona for scenes like this.

Just to be sure - could you send us this scene? https://coronarenderer.freshdesk.com/support/tickets/new We would just check if everything is correct. Maybe at least some speedup is possible.

Title: Re: crystal rendering slow
Post by: Correntes on 2016-11-17, 13:35:57

Maru: sent  the whole scene by wetransfer.

Right now we have vray, I'm thinking in buy a couple of corona licences to the office so I'm comparing corona to it.

In this particular scene, Vray is also slow but noticeable faster than corona.


I i understand that a scene like this will be slow but how come I see allot of renders in gallery with crystal glasses in close up ?
People just let it render ? In "in house" works that's ok but in production its not viable.
The video from alex roman to silestone comes to mind. That in corona would be possible in reasonable time (with reasonable hardware like 4 or 5 dual xeons ) ?

Title: Re: crystal rendering slow
Post by: Ludvik Koutny on 2016-11-17, 16:25:22

There's currently a bug that causes extremely slow rendering of many overlapping refractions when caustics are disabled. This could be your case too. Try to enable caustics on your refractive material.

Title: Re: crystal rendering slow
Post by: Correntes on 2016-11-17, 18:05:11

Rawalanche:

Yeah enabled caustics and definitely helped. Still slow but helped.

Is this bug a priority at the moment ?

Title: Re: crystal rendering slow
Post by: Ludvik Koutny on 2016-11-17, 18:13:19

I don't think so... but that's up for Ondra to say.

Is there any reason your crystal material has enabled diffuse, other than making it look worse? :)

Title: Re: crystal rendering slow
Post by: Correntes on 2016-11-17, 18:56:10

yeah i'm struggling with the material.

Right now I have difuse disabled with translucency at 0,8 fraction. If not I have allot of black.
Still not satisfied though

I had also a problem with mapping...

Title: Re: crystal rendering slow
Post by: Ludvik Koutny on 2016-11-17, 20:05:57

There shouldn't be any diffuse or translucency in crystal material. Otherwise it will be slow and look wrong

Title: Re: crystal rendering slow
Post by: maru on 2017-08-02, 15:31:08

I'm happy to announce that the bug causing extremely slow hybrid glass rendering (solid glass with caustics disabled) has just been fixed.
It will be soon available in a daily build:
https://coronarenderer.freshdesk.com/support/solutions/articles/5000570015-daily-builds