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Flicker Free City Scene

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Flicker Free City Scene

Unread postby grabiller » Mon Jan 28, 2013 3:45 pm

Hello,

Just out of curiosity, do you have a scene version of the City sample scene that can be rendered without flicking ?

I've created a slow camera forward dolly movement, and tried a lot of settings changes (camera sampling, light/shadow sampling, gi sampling etc..) and so far, I've been unable to produce a flicker free animated sequence.

I've disabled GI, still flicking, especialy in high density area. I've enable mipmapping, still flicking.

I'm just discovering Clarisse so I may not look at the right place. Any idea/hint on how to produce a flicker-free animated sequence on this scene ?

Aside from that, I like very much the design/approach of Clarisse.

Thanks,
Guy.
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Re: Flicker Free City Scene

Unread postby isoyann » Mon Jan 28, 2013 4:06 pm

Hi,

This scene contain very high frequency details (lots of small objects per pixel in the background). Unfortunatly, there is no secret to get flicker free animation with combined slow movement / ultra high detail density : the problem is the same for any renderer, without using LOD, when you fire rays in the background (for example 10 rays), in each frame, each one will hit a different object (or detail.. ) and return a different color. For this scene, you must set the antialiasing samples in the raytracer to 8, which give you 64 samples per pixels, with blackman-harris filter. This is generally a good number for this kind of scenes.

A better approach is to render the background on a different clarisse image, with a second camera, and project it on a plane in the background of the main render. This way, you will be able to render the same scene very fast, without flicking (this is the kind of setup used in the 3dmatte project). This setup will still be interactive, and if nothing is moving, clarisse will render it only once...

Thanks for your interest in Clarisse,

Yann
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Re: Flicker Free City Scene

Unread postby grabiller » Mon Jan 28, 2013 4:17 pm

Hello Yann,

Indeed that's a good idea and it makes sense, I'll investigate this path.

Cheers,
Guy.
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Re: Flicker Free City Scene

Unread postby aweidenhammer » Sun Feb 03, 2013 4:56 pm

Bits of geo that are so small that they cover less than a pixel can be a nightmare for many raytracers. Some handle it in different ways. If you set the BG to a layer, you could upres the BG layer to avoid the sub-pixel issue, or do as suggested, and make it a "plate".

Some renderers might use camera distance to swap BG geo for voxels, which can improve flickering issues. Even if you can't render voxels, you might use distance to swap objects for blockier versions with much less high-freq detail, or detail baked into textures. Is there anything like that supported in Clarisse?

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Re: Flicker Free City Scene

Unread postby isoyann » Mon Feb 04, 2013 3:51 pm

Some renderers might use camera distance to swap BG geo for voxels, which can improve flickering issues. Even if you can't render voxels, you might use distance to swap objects for blockier versions with much less high-freq detail,


In the current version you can already setup LOD distance swap using distance clipping on 3d layers : for example, set the layer A to near clip 0, far clip 500m, and layer B in background set to near clip 490m (a little overlap give better results), far clip to infinite. Then use a low def version for objects in the layer B geometries group... you can even use two different raytracers, using more samples for the background.

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Re: Flicker Free City Scene

Unread postby aweidenhammer » Mon Feb 04, 2013 8:28 pm

Cool. I'm running some flicker tests (different AA and filter settings) on some very dense leaves on a tree scatter setup. When I get home I'll see some results.
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Re: Flicker Free City Scene

Unread postby capsilus » Mon Jul 29, 2013 8:19 pm

Will there be lightcache/irradiance map precalc's like in vray? That always helps me eliminate flicker from massive scenes.
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Re: Flicker Free City Scene

Unread postby isoyann » Tue Jul 30, 2013 6:08 pm

Yes, this is planned for future releases of Clarisse... we are open to any render techniques than can help our users to get faster/better results in specific cases and irradiance cache are part of this. But keep in mind this will not help for geometric aliasing (this is the main source of flickering in massive scenes.. lots of details smaller than one pixel).
In 1.5 you will be able to add a little bit of Depth of field.. this can help for very thin details that are far away from the camera (in real life, even with a very sharp lens, they are blurred by atmosphere ).

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