Caustics quality

[Micha_cg]

Caustics quality

Two ideas from my workflow:

... if you can, use the _renderwindow command for critical areas. I have used it for area shadow noise tests. OK, if you would use a photon map, than it will not work so good.

... if you can calculate high res images without to much time increase, than you could render a high res image -> denoise the critical areas -> downscale the image. This method help to keep the details and to kill the noise.

[flipside]

Caustics quality

Can you point me in the right direction to 'denoise' an image?

[Thomas An._cg]

Caustics quality

... if you can, use the _renderwindow

Yes, that is a good way to go for IR+LC. I usually sample small 10x10pt areas here and there and they render within 60 sec at good settings to check how smooth is the GI in that area.

... if you can calculate high res images without to much time increase, than you could render a high res image -> denoise the critical areas -> downscale the image. This method help to keep the details and to kill the noise.

I would be carefull with that approach. You have suggested it for Maxwell as well, but it may not be the best way to go and I don't know if it really saves any time). If you double the size of the image then you quadruple the area so the render time goes up.

Instead of scaling up, I would render at the actual rez, but then scale it within photoshop in order to take denoising samples. Also, another way is to copy/paste a few squares of noise and tile them on the side of the image in photoshop (make the canvas larger to have room) and then use those those tiles for the denoiser.

Also, I have found that the built in denoiser from Paintshop pro is just as good and more convenient than using NeatImage.

Vray, is overall quite smooth so we don't need to denoise too often (except maybe some areas from the DOF or some low noise left from the GI due to incorrect settings)

[Thomas An._cg]

Caustics quality

Can you point me in the right direction to 'denoise' an image?

Wouter, there is denoising software if you scroll down this post:
http://www.asgvis.com/phpBB2/viewtopic.php?t=202

I find that the built in denoiser in PaintShop Pro does a very good job. You can lasso-select specific areas (use feathering for the lasso outline) and then denoise those areas only.

[Micha_cg]

Caustics quality

Thomas, you could add IrfanView to your list. It is for free and bring a good upscale algorithm (also used in pro software).

http://www.irfanview.de/

More infos here: http://www.fredmiranda.com/SI/index.html

I use the upscale, if I want to quick print an image, but dosn't like to render it again.

[Thomas An._cg]

Caustics quality

Thomas, you could add IrfanView to your list. It is for free and bring a good upscale algorithm (also used in pro software).

http://www.irfanview.de/

More infos here: http://www.fredmiranda.com/SI/index.html

I use the upscale, if I want to quick print an image, but dosn't like to render it again.

I prefer XnView, have you tried it ? (it is free too and I like it a little more than Irfran view)

[Micha_cg]

Caustics quality

Impressiv list of image formats ... and hdr.
Seems to be a must.

[Thomas An._cg]

Caustics quality

Impressiv list of image formats ... and hdr.
Seems to be a must.

[Thomas An._cg]

Caustics quality

http://www.chaosgroup.com/forum/phpB...=14303&start=0

This thread looks interesting. This fellow is having similar issues starting out, so his progress would be interesting (rendertimes and glossy objects).

[Thomas An._cg]

Caustics quality

Wouter,

Do you think the missing options: "Use Irradiance Map" and "Treat Glossy Rays as GI rays" on the material editor would play any effect in speeding up the noise on the coins any further ?

Regards

[flipside]

Caustics quality

Definatly not the use ir map option. This is by default on, and if you turn it off, you are saying that the lighting should be calculated by QMC GI on that object. Imagine you have a whole scene which requires only low IR map settings, but there is 1 object that needs to be ultra fine GI quality, then you could turn off the 'use ir map' option for that material.

Not sure about the other option.
Vray manual:
Treat glossy rays as GI rays - this specifies on what occasions glossy rays will be treated as GI rays:

Never - glossy rays are never treated as GI rays.

Only for GI rays - glossy rays will be treated as GI rays only when GI is being evaluated. This can speed up rendering of scenes with glossy reflections and is the default.

Always - glossy rays are always treated as GI rays. A side effect is that the Secondary GI engine will be used for glossy rays. For example, if the primary engine is irradiance map, and the secondary is light cache, the glossy rays will use the light cache (which is a lot faster).

[Thomas An._cg]

Caustics quality

Definatly not the use ir map option. This is by default on, and if you turn it off, you are saying that the lighting should be calculated by QMC GI on that object.

Thanks. I didn't know it was on by default

Not sure about the other option.

Yeah I was reading that, but without testing I am not sure what the effect really is.

[flipside]

Caustics quality

same here

[Thomas An._cg]

Caustics quality

Someone (Vlado ? ) posted this at CgTalk.

I think, on the technical aspect, it is the best render I have seen for this scene. It beats the Maxwell images too in terms of clarity.

The only thing .... I wish we knew something about the photon map settings for the 5 hour image:

[vlado]

Caustics quality

The caustics photon map settings were 30,000 caustics subdivs for each light; in the render settings: search distance: 0.2; max photons: 0; max. density: 0.04. I'm not sure if the scene scale is the same between the different versions of the file though.

The resulting photon map was huge, a little less than 3GB, but this was not a problem since I rendered the scene on a 64-bit machine with 4 GB of RAM under WinXP 64-bit edition. Even though I used a 32-bit version of V-Ray, the 64-bit version of Windows can give a lot more memory to an application than the 32-bit version.

Also, I should note that the machine was a dual dual-core AMD Opteron at 1800 MHz, so that means 4 rendering threads. If I had to render on a single-processor machine, it would have been about 21h of rendering.

Other than that, the primary GI engine was irradiance map, and the secondary - light cache with 1000 subdivs. "Use light cache for glossy rays" was off. AA was adaptive QMC 1/100, and the noise threshold was very very low - maybe about 0.0004.

Also, while testing the scene, I found a bug in the photon mapped caustics - they were darker than they should be, so I had to fix this first.

Anyways, it's a very difficult scene (precise caustics in V-Ray in general are hard to deal with); although V-Ray did a fairly good job in the end, I think it should be possible to make it better and faster with less memory... just need to figure out how

Best regards,
Vlado