Shadow Problems

[meowviin]

I'm quite new to Houdini and I'm not sure if I'm putting things in correctly though. Im using a GiLight to create the AO but even after I turned it off/ Delete it. the problem is still there.

I'm facing really bad shadow patterns on my stairs after i rendered. It happened to gives me the feeling of a moire pattern. But, when i turned off all the shadows. It is still happening. I tried to change my texture as well but It is still happening. Can someone advise me please.

I tried to change the lights color as well.

It is an animated camera and this is the problem I'm facing over two frames.

BUT I'm suspecting that, It is not a shadow problem since I'm already tried to disable shadows and lights one by one.

Thanks,

meowviin

Edited January 4, 2011 by meowviin

[LaidlawFX]

do you have a scene file you can upload?

[Macha]

I can hardly see whats on that image, but is it an aliasing problem? What if you change the filter type or size, or increase dicing or anything else related to it? Randomize the position a tiny bit, etc.

Edited January 4, 2011 by Macha

[meowviin]

@LaidlawFX: I'm sorry, but I'm not suppose to upload any source from my intern company.

@Macha: I'm not sure if its an aliasing problem, but I don't think its a shadow problem definitely, since there are no light sources after disabling them and they still exist. Where do i change the filter type or size, or increase dicing? I'm quite new, and just started picking up houdini during my internship. It is a staircase with blocky shadow during animation.

Thanks in advance for your suggestion though.

Edited January 4, 2011 by meowviin

[meowviin]

this is the animated sequences and that shadow-like black blocks on the stairs is the problem.

I don't know if increasing the filter will take longer to render, because it definitely does for maya.

Currently, for my scene, it takes like 5-7mins to render. Are there any advise to reduce the rendering time as well?

Edited January 4, 2011 by meowviin

[LaidlawFX]

It's hard to get enough info from those little thumb nails. You should be able to create a new scene from scratch you can upload here to help of just the step pattern. If you can repeat a problem in a separate isolated instance it is a lot easier to fix it. a simple scene please? It would make the fixing go quicker. It's what you would need to do for sidefx for them to answer your problem. Here is a stab in the dark at any rate.

It is possible the pattern is being created by fine detail in the stairs. For instance if each step is made of a separate stones. If it is fine geo get rid of it for a simple box across the whole stairs. if your image is goign to be that small. If you plan on blowing up the image make sure their real is a problem at that scale

Otherwise in the mantra rop... you can play with the random seed, noise level, and jitter with out any real render time increase. to change the sampling patterns

For render time increases you can play with pixel samples and min-max ray samples depending on the render engine there are separate setting to adjust for each engine. If your are not using the mantra renderer then that would be helpful to note.

Also if you use motion blur in the end it may just blur it away.

Are you using depth map shadows or ray trace shadows? Different problems can arise.

Is the black pattern on the brown at the top a texture or from a depth map shadow? If this is a texture then you need to increase your sampling on the light and the mantra rop to fix the stairs.

What are the make up of the lights in the scene? an environment light will cause natural AO to begin with, so you do not necessarily need to use a separate pass to do this.

[meowviin]

I tried turning off all the lights already to slowly debug the issue, but eventually. I ended with a default distant light, without any shadow. The problem still persist.

i Tried removing the texture and change it already. But it is still the same. Even when i use a blank texture.

I plan to use Ray Trace Shadow for my scene in the end. But in order to fix my problem, I had to turn off my shadow first. So, there are no shadow in the scene when i tried to bug fix it. The image that i provide has Ray Trace Shadow casted.

How do i play with random seed and noise level, and jitter?

[LaidlawFX]

I tried turning off all the lights already to slowly debug the issue, but eventually. I ended with a default distant light, without any shadow. The problem still persist.

i Tried removing the texture and change it already. But it is still the same. Even when i use a blank texture.

That seems like it me might be a geo problem, where each step is built out of individual pieces of stone or cement, or some mantra issues.

I plan to use Ray Trace Shadow for my scene in the end. But in order to fix my problem, I had to turn off my shadow first. So, there are no shadow in the scene when i tried to bug fix it. The image that i provide has Ray Trace Shadow casted.

So when the shadows are off there isn't a problem? Is that right? You'll need to increase the shadow sampling quality on the lights to smooth out any shadow noise, this is connected to the pixel sampling quality and min-max samples on the mantra rop on the properties/sampling tab. At least it ain't a deep shadow problem.

How do i play with random seed and noise level, and jitter?

Ok so with out seeing the scene I'm gona say this from scratch. Go to the out network and find the output driver. There should be a mantra rop already there, if not place one down so you can adjust the parameters for the render engine, on the main tab set the camera to your scene camera. On the properties tab set your output picture to render directory. On the render tab set the render engine to Physicaly Based Rendering, PBR, if straight polygons represent a majority of your scene, if nurbs or sub-d represent a majority of your scene use the micro PBR. Also I only suggest PBR if you are using H11 or greater, other problems will pop up. If you are using the irradiance function, volumetrics, or not using area lights heavily switch it to micropolygon or raytracing.

On the Properties/sampling tab to directly answer your question is where the random seed, noise level(mr anti-aliasing contrast), jitter(mr equivalent), sample lock(mr equivalent) are, these do not do miracle work but they'll change up your sampling points. To increase you sampling points you need to use pixel samples and min-max samples. PBR works best if you crank up max ray samples and slowly bring up the min, pixel samples won't increase render too much in PBR mode, but will slow your scene down in micro polygon. This area should increase your render times, but you should be able to get ride of the step issue. This is kind of the equivalent to the min max samples in mental ray in may or the visibility and sampling quality on the rasterizer.

[meowviin]

When i turned off the shadows, they are still there. So definitely not shadow issue i guess. I did some of your steps. But it is still there.

Randomly, i clicked on, Increasing the Geometry Shading QUality from 1 to 2. It kind of fixed the problem.

Thanks for all the advise and tips that I can use probably on another bug or improve my scene with it!

Thank you, Thank you!! =D

[LaidlawFX]

yeah that's the geometry dicing, it chops up your micro-polygons even finer(increase the number of shader samples thusly). It'll def do the trick. I'm glad you found it.

The reason I don't suggest it straight off is that by default it is not the most efficient way to improve a scene(my personal opinion). But if it works, it works, all scene are built dif. It's def the default of the old school guys.

peace

Edited January 6, 2011 by LaidlawFX