VRay's ppt rocks!

[studioDIM]

I'm using for the first time the ppt mode of vray to render a lift with loads of glossy (inter-)reflections...

It's SO quick i'm getting excited every time i push the render button.

Previous tests with standard rendering methods led to very long rendertimes (over 9 hours on my AtlhonXP 2250 mhz) and lots of grain, even at the highest subdivs levels.

Ppt is resolving loads of tiny modelling detail with great accuracy, and converges VERY quickly to an acceptable noise level, no matter what i throw at it.

I hope i'll be able to post an image when the job's done.

For now, confrabulations to the team!

Lele

[timmatron]

Can you show an example? I haven't really seen a ppt rendering without a lot of noise yet.

[vance3d]

Yeah, I'd like to see what you mean by an acceptable noise level. My tests have required loads of time to get it to a level I think would be good for broadcast TV.

V Miller

[studioDIM]

here's a crop of a testrender (watermarked, sorry...) at 288*512

Edit: ALL the surfaces in this picture exhibit some degree of glossy reflectivity (from 0.975 to 0.6), even though it's not quite visibile at this size. There isn't one surface without them.

I'm not speaking about broadcast animations, though.
Rather, architectural/design viz.

I left it running when i left home to do some shopping for food, and came back.
I'd like to stress that this was clean-ish after under 10 minutes of rendering(250 or so samples per pixel).
This was stopped at 1h51minutes (1155 samples/pixel).

I will let you know more precisely what kind of sampling is needed to get it properly cleaned at the target resolution of 1024x2048.

regards, Lele

[studioDIM]

Err, one question:

does ppt works with DR?

I know Lightcache doesnt, but ppt?

Lele

[timmatron]

I will let you know more precisely what kind of sampling is needed to get it properly cleaned at the target resolution of 1024x2048.

Looking forward to that, thanks.

[Morbid Angel]

no ppt does not work with dr. As its based on the same method as LC

[studioDIM]

Oh, thanks Morbid Angel.

Lele

[vlado]

While ppt doesn't work in DR mode, you still can split an image across several machines. However, this would only work for still images:

(*) Uncheck the "Time-independent" option of the QMC sampler.
(*) Uncheck the "Clamp output" option in the Color mapping rollout, since we want HDR output.
(*) Even though you are rendering a still image, set the rendering to an animation range.
(*) Make sure you are rendering the animation to .hdr images.
(*) Use backburner to render the animation.
(*) Blend the resulting images in an image processing program.

Since each image has a different noise pattern (because of the time-independent option), blending them would have the effect of averaging the noise and thus reducing it.

Rendering to .hdr images is essential, as otherwise you will not get a correct averaged result. Programs that process .hdr images correctly are rare, but if anyone is interested, I can get them a program that does the last step - blends a number of .hdr images into one final image.

I used this approach to render the image for the "Caustics II" thread, although in that case I used photon mapping and not ppt, but the principle is the same.

Best regards,
Vlado

[sv]

if anyone is interested, I can get them a program that does the last step - blends a number of .hdr images into one final image

yes i'd be interested in knowing this.

[studioDIM]

Since each image has a different noise pattern (because of the time-independent option), blending them would have the effect of averaging the noise and thus reducing it.

Ahahah, CLEVER!

I'll give it a try as i get to the studio on Monday

BTW, results are really really good as things stand.
I asked just as an icing on the cake :P

one more question, though:
is there a difference in rendertimes if materials' diffuse value + reflection value exceeds 255?
I've seen a thread on a competitor's forum (one that has a similar, but less efficient method that ppt ) that explained how that would change for the worst the rendertimes and the quality of the output image in terms of contrast.

I can't say I noticed a huge difference so far, but some higher range noise did pop up with a plastic that exceeded the 255 value.
Was it my perception, or it does matter to an extent?
"Unbiased" and all of that is getting to my imagination, i guess...

regards,
Lele

[dennis]

Since each image has a different noise pattern (because of the time-independent option), blending them would have the effect of averaging the noise and thus reducing it.

i guess this is a bit like maxwells 'cooprative rendering' ?

[jujubee]

Hey Vlado - a little side-question - will there be the ability to calc Lightcache over DR?

[studioDIM]

Rendered a full size one overnight (1152x204, for 5.5 hours, and without any post-processing, these are the results...

here, 350kb

[studioDIM]

Since each image has a different noise pattern (because of the time-independent option), blending them would have the effect of averaging the noise and thus reducing it.

Now now..
So i rendered my 2048 image overnight, stopped at 5 and a half hours, and am happy, but it's not quite there yet.
So i move to frame 1, render for another couple of hours, then blend the new image back in the old one.

Voila', VRay's ppt has a "Resume rendering" function
Oh, and it's not disabled in this release, either...

Now, what was the proggie you were talking about, Vlado?
I was thinking of using combustion with some weird blendmode on rpfs or exrs, but i guess there's better...
Photogenics can do it? It seems spot on for HDRI painting and retouching...

re,

Lele