Hi, I’m new to blender and I have not made a big scene.
I did a rendering in blender cycles, the same scene in LuxRender renderize, trying to configure the same.
These were the results.
the first rendering in cycles, with 1500 samples did not look good
In blender cycles with 2500 samples per pixel.
uhm, the lighting looks totaly different, did you remove the default background shader for cycles? the main difference you should see is in the caustics, beacuse we don’t have bidirectional pathtracing (yet).
Cycles and Lux are two very different rendering engines. The comparison is lacking as well, as you don’t mention the type of integrator you used with Luxrender.
The goal of Cycles is to be an engine for animations, while Lux is a full spectral renderer based off of PBRT. Any scene with caustics in Cycles is going to take forever, simply because its integrator isn’t designed to handle them.
sorry, it’s true that bad recreate the scene, but as I said I am very new to blender (just a few months) and still not do many things gladly share the. blend although the rules say you can not I post links and if you can not put a download link. I will try to recreate the scene better for both cases. Thanks for the clarification of LuxRender and cycles.
My video card is an ATI 5570 ddr3, so I can not do with GPU render. My cpu is a core 2 duo e8400 to 3ghz each core and 8gb of ram. Sorry if the translation is bad
@marcoG_ita
Haha, thanks for clarify. Yes, it was my idea.
@Redwood
Cycles is pure Path Tracer. It track light paths from camera to objects , with direct light feature to sample light sources that can not be hit from camera (point and spot lights). For caustics you definitely need good HDR background or triangle mesh with emission as light source. Imagine, how hard to hit small light square from camera, solid angle so small after interreflection inside glass object. As marcoG_ita said, i have very experimental patch that trying to extend Cycles with bi-directional features. It still lack many of real bi-directional features, but at least it can sample from light to camera if last hitten object can be “evaluated”, it help with caustics a lot. I asked tor .blend just to try it myself and podt result here, maybe in 2 hours it can render with quality close to Luxrender.
It’s an implementation of Veach-style bi-dir with participating media. The blog is really interesting as a whole too, I’ve been reading it for about a year.
A GTX460 is probably around 8x faster or more than your CPU. A better card is even faster.
And luxrender is not able to use a card like Cycles does.
Luxrender can use several methods, not only path tracing that at the moment is the only thing Cycles does. But Path Tracing is pure brute force. So really is not fair to compare luxrender and cycles at the moment. For me luxrender is much much better than cycles. But Cycles is hyperfast if you have a GPU card and your scene doesn’t use things Cycles lacks or fails (caustics for example are not a good thing Cycles does because Path Tracing is not able to see where caustics are and focusing there with more samples that other methods do. So with caustics luxrender will be much better.
Also luxrender is spectral render, you can tune the lights to emit a range of wavelengths. Cycles uses lights that are only that wavelength. So the realism you get with luxrender is much more realistic than with Cycles that always have that “plastic” look when compared to same done in luxrender. But well you can mask this using HDR where the light is from so many points and so many different wavelengths that the result you get is similar in both renderers.
So you need to know what each renderer can do the best and choose. At the moment Cycles is far behind in development so its only advantage when compared to luxrender is speed. But I am a fervient fan of luxrender and you can tune luxrender to be not much slower than Cycles.
Do you see those caustic rainbows to the right? That is what a spectral renderer is able to do and a not spectral (Cycles) can’t do. Don’t ask to Cycles to give caustics so wonderfult like luxrender can do. Cycles can’t do it until some other methods than Path Tracing are implemented, like Bidirectional.
Welcome to blender by the way. This program is really fun and a lot of things are being developped and going to be added in the coming months. Exciting times ahead.
I must have forgotten to save the file, but it’s simply three glass shaders, one red, one green, one blue, the red one with an IOR of 1.4, Green with 1.45, and blue with 1.5, added together. It takes tens of thousands of samples for the caustics to show up(though the refractive abberation is quite fast)
That was very good, with more samples would be better. I want to learn to give that effect
More samples actually doesn’t help. I probably have the same setup as OL77, but after a while most of that color that you see goes away and becomes flat looking again. This is what it would be with more samples:
Well, in principle it should work, blue light is refracted more than red light, even if the “resolution” isn’t so great for the transitions between red green and blue.
Do we really need spectral sampling? It is very easy feature, any one can add basic in few days if not hours. Jiggle wavelenght, make [RGB]<->[Intensity, wavelenght] conversion, and maybe black body light source for more coolness. Very few places must be modified, Fresnel calculation, and glass shader.
Hi storm, I’ve got no knowledge of how cycles or ray tracing works but I am trying to learn what I can. Can you tell me why an HDRI would work well for caustics? I kind of understand why triangle meshes would be good, but it seems HDRI’s would be worse than lamps.
As for spectral sampling, I think it would be good and it would make cycles more ‘mature’, and it could be useful in special cases, but Bi directional should be much higher on the priority list I think. (how is that going BTW?) Would spectral sampling have any effect on speed, or would it be an option to turn on and off? This would only cause the rainbow (spectral) effect right, not help with sharper caustics? Sorry, as I said I know nothing about cycles code.
Thanks for all you’ve done so far, I can’t wait until your code is completed and put into trunk! (I know it takes time)
