Flickering in MPR rendering

[zasid]

I have project deadline next week and m getting flickering in my AO Pass

here are my settings

Arealite turned into enviroment lite Using HDRI

Geometry on Motion blur.

Mantra setting is ALLOW MOTION BLUR and rendering engine is MPR

but its is flickering please help me out

Many many thanks !!!

Zasid.

[symek]

I have project deadline next week and m getting flickering in my AO Pass

here are my settings

Arealite turned into enviroment lite Using HDRI

Geometry on Motion blur.

Mantra setting is ALLOW MOTION BLUR and rendering engine is MPR

but its is flickering please help me out

Many many thanks !!!

Zasid.

I can't tell you what's going on in your setup (haven't seen it) but:

1) Try to pre-blur your hdri map (a lot).

Alternatively:

2) Try to use an ambient occlusion shader with bend normals and HDRI map applied on it. You will get more stable results with it + you will be pleased with advantages of irradiance cache this shader can utilize.

Such shader, perhaps the best solution for image based lighting, isn't included in H., but there are a number of examples for it starting from a fresh thread here:

http://forums.odforce.net/index.php?showtopic=7077&st=12

At the end, it seems to be complete code (I haven't tested it though).

cheers,

sy.

[zasid]

Hey Symek I m quite new to all this and I really dont know how to use this code can u please tell me how to use it ??Many thanks .

Where can I get this AO Shader with bend normals?

[symek]

Hey Symek I m quite new to all this and I really dont know how to use this code can u please tell me how to use it ??Many thanks .

Where can I get this AO Shader with bend normals?

Did you try to pre-blur you HDRI map? You should, it also can help a lot.

As to shaders:

Take a look at the long post of Mario on a second page of the thread. Code "Version 6" is probably what you want.

Open Houdini. Menu File -> New Operator Type -> Light Shader (name it some how, choose OTL to save your new shader in it, Accept -> Code Tab -> Paste the code there (note credits for Mario;) ) and Accept.

Add new Light Template into a scene and apply new shader on it. Setup shader's parameters (map for example). Go to Mantra ROP and turn on Irradiance Cache. There are more parameters for that cache, which you can add via Edit Rendering Properties. Done.

EDIT: HDRI should be pre-blured also. There was a significant change in a way Mantra was bluring RAT texture of the fly. I don't remember the build but for some point, you could easily ask mantra to blur map in rendertime in 200pix without slowdown. The problem is that cubic environmental maps start to show corners if heavy blurred, Thus pre-blurring is the option.

Edited May 31, 2008 by SYmek

[rob]

Hello ,

Sorry its been a few days I had a computer drive fail on me obviously thats delayed things for me. Theres two occlusion shaders to roll out with all the code completed and I have done a flicker free fighting teapot scene using the Irradiance caching which will work for you zasid.

Look at the Mantra node , notice how the irradiance is being written out !! thats the secret . It will certainly helo you get over your production hurdle.

Post up some project images ...

Rob

rs_irradianceTeapots04_H9.1.hip

Edited May 31, 2008 by rob

[zasid]

Thanks alot ROB.I will surely post up some images as soon as I get a chance.let me just check your file first.Thanks a ton!

[zasid]

Hey Symek ,

Yes I have been using a pre blured HDRI map.What I did was it was basically at 1300X500 HDRI so I brought it to cop network blur and resize it to something like 500Xsomething to make it smaller .I think that should be ok.Let me post the example hip file so that you guys can have a look.

thanks

zasid

[zasid]

Ok guys here is the exact hip file that I am using.

I didn't enable the motion blur in Mantra to render it quickly but I m using MicroPoly PBR renderer and this is the problem I m having take a look at the anim file and then

see my hip file setup.I am not including texture.rat files as they are increasing the file of the zip but I have made the hip file for you guys to test at exactly the same setting I m using.

If you notice in the last 5 6 frames the lite kind a flicker like thunder storm effect also:).I really have no clue how to fix this and will be very thankful for your help on this.

Many Thanks

Zasid

problem_anim.mov

MPR_PROBLEM.zip

[zasid]

Hello Rob,

This is the test I just did with your file.and the problem is still there.I am using displacement value quite high I think does that has any thing to do with this flicker also?

Please see the attached anim

SCRACKED.mov

[anamous]

Is there a specific reason why you are using micropoly PBR? you mentioned this being an AO pass, in that case I think it's much wiser to use normal micropoly mode with a light template object pointing to a VEX Global Illumination light shader (where you can also specify your HDRI). also, get rid of the environment light in that case. IMO it's the easiest way to get an AO pass.

If you definitely want to use MPPBR, you have to greatly increase both your shading rate and your minimum ray variance count to get flicker-free results. the shading rate can be found on the object's render tab, and ray count can be found on the Mantra ROP under Sampling/Min Ray Samples. You should be setting the shading rate to something like 2 or 3 and the samples to something like 200 before things get interesting. Please be aware that rendertimes will explode.

Also, if you need PBR and don't mind some grain, you can try the normal PBR engine, set the pixel samples to something like 30x30. the grain will mostly be static which in some cases even looks nice.

cheers,

Abdelkareem

Edited May 31, 2008 by anamous

[symek]

Hello Rob,

This is the test I just did with your file.and the problem is still there.I am using displacement value quite high I think does that has any thing to do with this flicker also?

Please see the attached anim

Upss, like anamous said. I don't see the reason for using PBR nor MPBR here. I thought by MPR you mean Micro-Polygon-Render. Follow Rob's setup to set AO efficiently.

cheers,

sy.

Edited June 1, 2008 by SYmek

[rob]

I have had a brief look at the file.

1) you have no lights in your scene ? key , fill etc etc

2) If you want occlusion use the light template and add the blurred .rat file as per the file I gave you

3) to find out why it flickers ...

Turn off displacement , what happens ...

Your geometry is fractured surely it would be better to fracture at the point of impact

R

[zasid]

Hello Rob,

For the AO Pass,I think I don't need Fill and key lite

I used one Area lite by making it an environment lite and yes I did used the blurred hdr that I have attached with that zip file.

Object is basiscally a fractured object that I imported from max so I cannot break it rite at the impact time.

I did turn of all the displacement for the test but the flickering was still there.

I also tried with ur method by coping ur nodes into my file but the flicker was still there.

I really dont know what to do now.

Many Thanks

Zasid

[rob]

Zasid ,

If the displacement map isn't causing the flicker and we know the occlusion doesnt flicker whats left is the primary suspect. Look at the fractured geometry you brought in.

[zasid]

Hello Rob,

You were so right !!! the problem is with the geometry.Actually I used a CLIP sop to divide my Fractured objects in 3 layers with 3 groups on it to put 3 different textures and the problem starts from their .I also used Facet sop that makes every poly unique so now when a I apply my shader with a displacement value of -0.05 which is quite high it sperated them apart and then I get a thck black like in between two polies and that is wat flikcer on the edges the most.Rite not I m struggling to fix it but I really don't know how to do it at the moment.Thanks for point me the rite way!!!