Indigo Renderer Forum

Hi all !

I hope you can help me (I'm french, please excuse my strange english).
I try to make glasses.
I've tried a lot of things :
- volume, thin glass material used
- volume, created specular material (ior 1.4)
- volume, glass indigo preset
(all faces "painted" with the material for each of these tries).
I tried every normals combinations, to paint only one face or to apply every material on a single face, nothing to do : my glasses are transparent but the sun light can't go through it...

Look (left window : a glass, right window : nothing)





I tried with all rendering methods, same result.

Thanks for your help, I'm lost.

Win7 x64
Indigo 3.0.12 trial 64bits
Intel Q6600@3.2 Ghz
NVidia Geforce 9600GT

EDIT : Ok, the Bidir MLT mode seems to work fine.
So the question is : is there a way to make the sun light go through a glass in pt mode (which allow the gpu use) ?

In your rendered image, you can see some "sparkles" on the floor where the spot of sunlight is supposed to be, can't you?
Thats what eventually will form your light spot.
Light through glass takes a long time to render, so just wait some more
I'd recommend using MLT BiDir in this case.

€dit: You can use PT with glass acceleration on the GPU, too.
I guess it will take some longer render times then, however.

Yes you're probably right. I will wait longer and see. Thanks for your reply.

ducon wrote:So the question is : is there a way to make the sun light go through a glass in pt mode (which allow the gpu use) ?

Yes, it's called Glass Acceleration and was introduced for PT very recently. Before that it was for bidirectional PT only.

If it's not yet available in SkIndigo it's definitely shipping. You can also activate it in the Indigo UI, once the scene is loaded and before the render is started. It is compatible with GPU acceleration.

I was absolutely sure to have tried with glass accel. checked !
It works fine now.
Thanks a lot.

Unless you are dealing with shaped glass volumes I'd suggest Bidirectional Pathtracing with Glass Acceleration.

While it was the direct light trough the window/door glass is what you were missing, most of your scene is actually indirectly lit and single directional path tracing is not the best rendering method for it

MLT (Metropolis Light Transport) may be overkill for this scene as well as the actual source of light is relatively large. MLT is called for if you have small sources of light combined with shaped specular materials. Keyword here is caustics.

Very nice atmosphere in your scene BTW!

Hello, I had problem with the glass also.

Let me ask a (stupid) question: Does GPU acceleration prompt you to use PT (Path Tracing) only?

munkey wrote:Does GPU acceleration prompt you to use PT (Path Tracing) only?

Yes, atm GPU mode only supports pure PT and switches to it if activated, but Glass Acceleration is usable with in GPU mode too!

Oh I see, thanks.

And I had also some issues with exit portals - they did not trespass the light from the sun layer (there were no shadows in the interior) - like in the image above. If I turned the GPU acceleration off, it was ok, but the render time was higher. What's the connection between glass & exit portals & GPU acceleration please?

munkey wrote:And I had also some issues with exit portals - they did not trespass the light from the sun layer (there were no shadows in the interior) - like in the image above. If I turned the GPU acceleration off, it was ok, but the render time was higher.

Yes, EP + GPU rendering is broken atm. I'm sure it gets fixed during some of the next beta releases

munkey wrote:What's the connection between glass & exit portals & GPU acceleration please?

Ehm.. strange question ^^

The GPU mode is ported version of Indigos PT render mode to work under OpenCL & CUDA for GPUs to work together in hybrid mode with the CPU. Porting it is no job of pressing a button but rather complex. So the GPU rendermode might still have some issues and room for optimization since this whole field is still quite state-of-the-art.
So this is the general Raytracing mode you choose here, while the other both are trigger optimizations to enhance render speed in certain situations that need to be decided by the artist if used or not.

Glass Acceleration was introduced not long ago to push light through Glass render situations further and enhance the calculations but having still a small reduction in general render speed for not related scenes, so its optional and not hard-coded.

The Exit Portals are a older tool in Indigo to focus calculations on certain openings where exterior light enters a room for example, very effective and a great time saver!

Hi Zom-B, I have a different perception than you about PT limitations. However to be fair I must state than I am not taking part in Indigo's own development, it's well above my head.

Zom-B wrote:Yes, EP + GPU rendering is broken atm. I'm sure it gets fixed during some of the next beta releases

While I am hoping to see PT enhanced in the future, I understood that it doesn't cope with portals well due to its very nature. At the most I may have understood that this limitation was a strategic choice before that nature: having an otherwise faster PT, at the cost of portals functionality.

That's to illustrate the artistic blur around the (complex) topic

Zom-B wrote:

munkey wrote:What's the connection between glass & exit portals & GPU acceleration please?

Ehm.. strange question ^^

That question may come from me, I suggested somewhere a relation with PT performances for each of: portals, and glass without Glass Acceleration.

Again I can't tell for sure, but a priori I am rejecting the expression broken portals with PT. I am hoping to be demonstrated otherwise with a "fix"

Headroom wrote:Unless you are dealing with shaped glass volumes I'd suggest Bidirectional Pathtracing with Glass Acceleration.

While it was the direct light trough the window/door glass is what you were missing, most of your scene is actually indirectly lit and single directional path tracing is not the best rendering method for it

MLT (Metropolis Light Transport) may be overkill for this scene as well as the actual source of light is relatively large. MLT is called for if you have small sources of light combined with shaped specular materials. Keyword here is caustics.

Very nice atmosphere in your scene BTW!

Thank you !

Interesting nickname!

Etienne

CTZn wrote:Hi Zom-B, I have a different perception than you about PT limitations. However to be fair I must state than I am not taking part in Indigo's own development, it's well above my head.

Zom-B wrote:Yes, EP + GPU rendering is broken atm. I'm sure it gets fixed during some of the next beta releases

While I am hoping to see PT enhanced in the future, I understood that it doesn't cope with portals well due to its very nature. At the most I may have understood that this limitation was a strategic choice before that nature: having an otherwise faster PT, at the cost of portals functionality.

That's to illustrate the artistic blur around the (complex) topic

Zom-B wrote:

munkey wrote:What's the connection between glass & exit portals & GPU acceleration please?

Ehm.. strange question ^^

That question may come from me, I suggested somewhere a relation with PT performances for each of: portals, and glass without Glass Acceleration.

Again I can't tell for sure, but a priori I am rejecting the expression broken portals with PT. I am hoping to be demonstrated otherwise with a "fix"

From what I understand, it also has to do with improving the importance sampling algorithms, so I guess 'Pathtracing' is a pretty broad term that could encompass a variety of techniques and new developments...

I could not pretend otherwise Tom, but my impression was that there was a choice/compromise beneath the current limitations. I like your angle more though.