VEX Glass : Evironment Map(Edge) Flickering or Jittering?

[cloudfx]

Hi all,

I have a cracked glass geometry and have VEX Glass assigned to it.

I put an full white image(not a sequence img) as an environmental map to make white crack line.

I am using "micropolygon rendering" because physically based rendering does not give me nice white cracked lines.

When I rendered sequence, the edge is keep flickering..

Its not step size of render I guess.

I guess I did something wrong and cant find what is wrong!

It is not from spec. Did anybody had like this kinda problem?

I just made an optimized scene and attached with rendered seq.

Please take a look if anyone get a chance! HELP!

Thank you very much!

glassRenderProblem.zip

Edited May 23, 2008 by Jae Yoo

[Jason]

Would you mind posting images of your desired effect?

[cloudfx]

Would you mind posting images of your desired effect?

I cant right now but I will make something else that I can post. The problem is the white cracked line is flickering like anti-aliasing problem.. but I raised sample rates and its still same..

It did not flicker at first time but it just happend.. hmm.

[cloudfx]

I cant right now but I will make something else that I can post. The problem is the white cracked line is flickering like anti-aliasing problem.. but I raised sample rates and its still same..

It did not flicker at first time but it just happend.. hmm.

Problem solved;;

I put Cache node after the extrube node to render and I had to update the cache data everytime I change my setting or should've turn on the bypass flag!!

I think that was why it was keep flickering!

Now, render looks fine..

But Thank you for fast replying, Jason!

[cloudfx]

Problem solved;;

I put Cache node after the extrube node to render and I had to update the cache data everytime I change my setting or should've turn on the bypass flag!!

I think that was why it was keep flickering!

Now, render looks fine..

But Thank you for fast replying, Jason!

Actually, Still getting the problem. I uploaded the optimized scene file so please take a look and help if anybody possible.

glassRenderProblem.zip

[cloudfx]

anybody help on this problem! there is attachment.

[symek]

anybody help on this problem! there is attachment.

This problem is, as you said, directly related to anti-aliasing of secondary rays in reflections. Some of Mantra's settings you should consider to tweak:

1). Min and Max Samples for Ray Variance Anti-aliasing. Puting Min to 5 solves the problem in my opinion.

2). You can tweak also Variance amount for above rays setting (absent by default, you can add this via Edit Rendering Paramaters

- in mantra ROP or

- on your glass Object or

- in a shader raytracing call (which is in your case gather() statement. This option implies creating your own shader possible coping all code from a default one).

3). Ray Shading Quality of Dicing tab of your object. This is separate quality control for ray tracing. It seems to not affect your scene though, but just in case...

4). You can also add to your object and turn on Raytrace Shading parameter. It will force Mantra to shade every sample instead of micro-poligon vertices. It greatly increases raytracing quality, but slows down render...

On my system the scene renders in 8 seconds without any of above steps, and takes up to 18 second per frame with the last (4.) change in settings. 1,2,3 steps takes about 10-14 seconds...

hope this helps!

cheers!

sy.

PS BTW Using Mantra in pure Ray Trace mode usualy produce stable reflections without any tweaking, but you end up without any micro-poligon advantages and noticable slower rendering, so this is a choice you should consider as the last I think.

Edited May 29, 2008 by SYmek

[cloudfx]

Thanks for replying so great.

That was really informative, but raytracing render and raise up the min sample value to even 5 to 16.. and it didnt really work out..

I still got the flickering..hmm

Is there something to do with filter?

Edited May 30, 2008 by Jae Yoo

[symek]

Thanks for replying so great.

That was really informative, but raytracing render and raise up the min sample value to even 5 to 16.. and it didnt really work out..

I still got the flickering..hmm

Is there something to do with filter?

You haven't included your environmental map in the scene, so I made my test with Houdini default HDRI maps, perhaps this was a reason for good results. Try other settings. Or attach scene with texture and we can look at it. I don't see why such scene couldn't be rendered properly in Mantra..

[stevenong]

Yep, like SYmek, I used one of the HDR maps that ships with Houdini: $HFS/houdini/pic/DOSCH_SKIESV2_01SN_lowres.rat and it works well. I believe there's too much contrast in the map you're using. Also, you might want to use the Facet SOP to cusp the sides to get sharp edges.

Cheers!

steven

[cloudfx]

Yep, like SYmek, I used one of the HDR maps that ships with Houdini: $HFS/houdini/pic/DOSCH_SKIESV2_01SN_lowres.rat and it works well. I believe there's too much contrast in the map you're using. Also, you might want to use the Facet SOP to cusp the sides to get sharp edges.

Cheers!

steven

HEY- that was it. I had too strong contrast.

I put 3 value of environment tint!

When I put the value as 1.

It did not flicker anymore. I see a little bit but it will be alright!

$HFS/houdini/pic/DOSCH_SKIESV2_01SN is work great!

Thanks!