reflection rendering speed optimization

[dryo]

Hello. Thank you for creating this amazing piece of software. I am in the middle of rendering a short animated film with Mandelbulb 3D. I have encountered a performance bottleneck with reflections. I was wondering if there was anything I can do to speed the calculations of reflections.

Currently I am rendering frames at 2K resolution. Certain shots have dramatically different reflection calculation times than others, even though the formulas and lighting are the same. I understand that the complexity of the shot will increase rendering time, but I am not seeing a correlation between subjective visual complexity and reflection render times.

Example:

Shot A calculates diffuse pass in one minute, reflection pass in two minutes.

Shot B calculates diffuse pass in one minute, reflection pass in one hour.

The two shots are different framings of the same formula, parameters, and lighting. Raytrace reflection Depth is set to a value of one.

It should be noted that I have analytical distance estimation disabled for aesthetic reasons-- I need the fractal shapes to remain consistent when changing camera zoom and transforms.

So, if there's any chance I can speed up these reflection calculations, I'd love to hear suggestions.

Best wishes, and many thanks.

Aaron

[Jesse]

Hello,
1 hour seems to be buggy somehow?
Would be great if you could send me those parameters as text in a private message, then i can look if there is an issue, thanks!

I can think of some settings that may cause longer render times for reflections, like not using 'vary DEstop on Z' and having rays that are follow very close a long straight object surface, with a relative high Zend value.
But 60 times longer that main calculation...

The analytical calculation can change the object as more iterations are calculating, but the non-analytical calculation also.
There might be differences that could maybe fixed with the DEstop value.  I already thought of an absolute DEstop value option so the object will always stay as it is, for animation purpose.  Zooming is not really possible this way.


The best is if i could have a look at that strange parameters, cheers!

[dryo]

Thank you for your reply. I just upgraded from 1.76 to 1.78 and that seems to have fixed the problem. I can still send you the parameters if you want to try to debug. Let me know if you want that.

By the way, while I have your attention, it would be great if there was a way to separately save out the various passes: alpha, diffuse, specular, ambient, ambient occlusion, and reflections. There's so much magic that can be done in post-production if the various elements can be saved to separate image sequences. Currently the z-buffer is all we have, although I haven't tried it.

Thanks once again,

Aaron

[PhotoComix]

--- it would be great if there was a way to separately save out the various passes: alpha, diffuse, specular, ambient, ambient occlusion, and reflections. There's so much magic that can be done in post-production if the various elements can be saved to separate image sequences. Currently the z-buffer is all we have, although I haven't tried it.
Aaron

i just wonder if your suggestion may be integrated in mine http://www.fractalforums.com/index.php?topic=10636.0 but maybe is more complex to implement