Do you like the grainy look on iray renders?
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Do you like the grainy look on iray renders?
I personally like it 
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No, not so much and in a couple of areas I have big white dots even after 8 hours of CPU render. The graininess can look a natural part of the render but the big white dots cannot.
yes one needs to define graininess as opposed to fireflies
this is a problem in all unbiased engines.
a bit of noise can just make it look like a fast film emulsion but emitters tend to create a different kind of noise that is quite distracting, Casuals despeckle is quite good for single images.
Videos I have a hard time cleaning up and get comments on youtube about not enough samples but what the posters do not realise is I can increase those samples 10x maybe even 100x in some cases with little difference other than making an animation impossible to finish rendering in my lifetime.
I blur where possible but that even does not remove it all.
Avoiding emitters seems the only answer, I tend to just render a lot of outdoor scenes!!!!
You can like and hate this render engine (iRay) at the same time.
The good thing about iRay is the real photorealistic light flow, compared with the workarounds for 3Delight (UE2-IDL).
But even at 99.5% of real "convergement" (as they call it), in the outdoor renders some shadow areas still remain badly grainy. In most cases I used the sun-sky.
And those light-specles only disappear above 99%.
I currently had an indoor scene with 4 ceiling lights, which even after 8 hours (cpu-only) still was at 0%. This time I used photometric lights (square areas) instead of mesh lights, as supposed somewhere here in the forum. But in the current case photometrics seemed to be way slower. (Did the same scene earlier with mesh lights using DAZ4.8). Or it's a general issue of the newer iRay engine.
Nope. Not at all. I especially hate it in promo images. Why would I buy something where I cannot see what the final product is really like?
tends to suggest that product does not render well either.
There are two possible conclusions:
1. The vendor doesn't have a sufficiant GPU card, or
2. the details of the product (polygons, sufaces, ...) exceed the capacity of a powerful GPU card.
In both cases: Renders with that product need an eternity.
As an old user of high-speed films the grain doesn't bother me, for most of my experiments. The wonderful handling of shadows yields so many surprises that I feel I have have so many other things to think about now, and grain isn't an issue. At least for now.
And anyway not all renders are grainy... some are silky smooth, reminiscent of using professional sheet films like Kodak Vericolor II, in the old 4 x 5 inch format. Not that I've used a whole lot of the latter but I *have* done some work in the past.
I have never seen grain with iray. It sounds like you have an under-powered graphics card.
Please see the area, the red arrow points at. The render needed about 8h to gain real 99.5% of convergement.
I'd be interested to know what GPU you are using. I would see a better result than this after half an hour or so
You're not likely to see much of an improvement with just changing the convergence ratio. These are underlit/indirectly lit areas which Iray will always have trouble with.
Instead, try increasing the rendering quality from its default 1. This value sets an internal threshold to what Iray considers a converged pixel. Values under 1 mean a lower threshold, and a faster render. Over 1 is the opposite. There is an approximately doubling in render time for each 2X increase in the quality threshold. You won't necessarily see a speed improvement in the render overall, but with experimentation with the render metrics, you could at improve the final result.
You might also play with the architectural filter, which provides added hints for indirectly lit areas.
Hi Tobor,
thank you for the explanation of the quality parameter. For 3DL (shading rate) it worked the opposite way round.
Applying additional filters (architectural, caustic) increases render times for sure.
As long as the GPU cards are not able to cover scenes with detailed environments, I prefer quick renders (at CPU-only) but optimum quality.
The scene above would need GPU-mem over 20GB.
Is that what the scene actually uses (as indicated by something like GPU-Z) or is it a guess? Textures, not geometry, tend to increase scene size the most. The jeep has little specific texturing (the paint doesn't need it; the tire textures are simple) and sand can be tiled. Human characters man require higher memory from texturing, but the shot distance is such that the textures are low res.
If the scene really does consume a lot of memory from the meshes, you can switch to Memory optimization, which flattens all geometry to one piece; however, this is at the sacrifice of speed.
I wonder if some of the slowness might come from improper shaders. This scene looks more like it uses 3Delight shaders that are auto-converted during rendering (lack of metal appearance in the trim of the jeep; "clay" appearance to some of the hair, etc). This is seldom efficient.
Hi Tobor,
you may have a closer look to the tire profile.
This is not simple bumb; it is real displacement. And for iRay you have to spend a sufficient amount of triangles / divisions. Same for the sand ripples.
Improper shaders? I used the iRay Uber Shader as the base to transform the surfaces. OK, perhaps I can tune some of the metal areas of the jeep better. And with the hair of the girl in the front right you're correct. This is an ugly hair prop. Have to exchange it as soon as I get some money.
But the memory need is what was reported from the task manager. I already subtracted what was occupied by the system and DAZ itself.
Related to the use of smaller texture maps:
This approach is not without problems. Even with not too small resolution you get a lot of artefacts. I got this trouble with a lot of sets. Had to magnify the affected maps by a factor of 4 to get rid of these.
As an experiment I changed the texturemap of a test prop to its half. On the memory need I didn't see any change. - Did this in a seperate experimental scene.