I'm triying to set up a mesh light only scene (AKA IDL emitter, isn't it?) in Poser Pro 2014 and I keep bumping into this problem.

The scene has three cubes with the default material shader and one set up as a mesh light with an ambient value of 10 and no shadows and visible in camer ticked off. Lights are turned off. The transition from light to dark is not smooth but full of that noise that makes the base cube looks as if it had a "sandy" bump map (seen more clearly on the second render)

These are my settings. I've tweaked again and again every little thing but the only difference I get is increasing irradiance catching reduces the "scale" of the noise but it keeps appearing. I'm running an up to date 64-bit Poser Pro 2014 on Windows 7 but the same scene and settings rendered in Poser 11 gives the same results. Can someone help me?

If you use a cube as emitter, what else did you expect than a grainy light? Remember the light on a location is only made from a limited number of samples. One pixel 'sees' 3 rays of light from the bottom of the cube and 1 from the side. The next 'sees' 3 samples from the side and only 1 from the bottom. Angles to normals of bottom and normal of side are significantly different so gives different amount of light. Use a sphere as emitter for more even result.

Thanks but I think that's not the problem. This is the result using a sphere. In the first example I used a cube but I've come across the same noise using a single sided square also.

Increase raytrace bounces from 2 to maybe 4. That will tend to smooth out light distribution. There will be a cost in render time.

Increasing pixel samples will also help, but it occurs all over the scene, not distributed with concentration on light bounces, so you pay a render time cost for less improvement.

Increase both irradiance caching and indirect light quality to maybe 70; that will cause Firefly to give more attention to light cast by a mesh. It will cost render time.

To save some render time, for Firefly, choose a bucket size which is an integer multiple of two, e.g., 8, 16,32,64,128. Avoid partial buckets at the edges of the frame by choosing a document window size (render size) in which both the vertical and horizontal are integer multiples of the bucket size, e.g., 1024x768, with a bucket size of 32.

Superfly has no speed advantage using integer multiples of two; just choose the bucket size and render size such that the bucket size divides evenly into both the vertical and the horizontal. 1200x750, with a bucket size of 30 (or 25, or 50, etc). Superfly will also be happy using the same dimensions as Firefly, such as 1024x768 with a 32 pixel bucket.

Gamma correction would normally be 2.2

Whether using Firefly or Superfly, be aware that lighting a scene with mesh lights comes at a cost in render time. One reason why so many of my test renders are night scenes is because I'm checking to see that the mesh lighting works; I also want to gauge how much of a hit in render time it incurs.

Another way to get a clean render quicker is to use a weak point light (inverse square attenuation) in conjunction with the mesh light. The mesh light provides the correct spread of cast light (because the light is cast from the entire surface of the geometry), and the Poser point light will clean up IDL grain/splotchiness.

Thank you. I've tried those values but the noise keeps appearing U_U

I have tried tweaking every setting, even to the point of not just turning off the lighst but deleting them just in case their mere existence was the cause. All I get is some difference in the noises's "seed".

My point is I've seen around a lot of renders done with mesh lights and none showed this noise nor anybody mentioned finding this problem. Does it happen only to me? Is there some kind of weird incompatibility between Poser Pro 2014 and my motherboard and/or OS? Then why it happens in Poser 11 too? It makes me mad because besides that fact mesh lights behave wonderfully. Look at those soft shadows.

It isn't just you; Firefly IDL tends to get those splotches in the absence of enough Poser light.

Here are some things you can do to improve it:

[_] Run two or three renders, each with somewhat different values in irradiance caching, IDL quality, and pixel samples. That changes the splotch "seed". Then blend those renders in PhotoShop.

[_] Use a weak Poser point light (attenuation set to inverse square) to supplement the mesh light. In P11 the point light is a ball mesh, so scale the point light up to increase its profile.

[_] use a ceiling (indoor shots) or use a skydome with the sky texture plugged into the alternate_diffuse socket of the root node. This gives rays something to bounce off of.

[_] Render in Superfly, with ambient boost applied to the mesh light cube (see the add-in nodes in this material sampler) The render caveats for Superfly is to give it maybe 16 meshlight samples, and 5 diffuse bounces. Set the overall pixel samples high, maybe 80, and then cancel/export the render once it clears up the graininess.

That puts my mind at rest. I'll follow your advice, thank you very much!