crystal rendering slow

[Correntes]

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 ?

[romullus]

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.

[Correntes]

I think you misunderstood me.

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

[maru]

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.

[Correntes]

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 ) ?

[Ludvik Koutny]

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.

[Correntes]

Rawalanche:

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

Is this bug a priority at the moment ?

[Ludvik Koutny]

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? :)

[Correntes]

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...

[Ludvik Koutny]

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

[maru]

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