when rendering a large image?

[reis0111]

Over the weekend i tried, unsuccessfully to render an image. It was 8500ish by 5500ish but the screen just remainded black during the rendering. I am using qmc as the first engine and light cache as second. Is this a setting prblm with the light cache, the subdivides or samples? Any help would be appreciated. :'(

[dalomar_cg]

Re: when rendering a large image?

Yea, I believe I've come across this before, and although I don't remember what the cause was I do believe that it was a similar type situation. My advice would be to change how you actually go about the calculations...in other words, just changing to a very large resolution won't work, but if you precalculate as much of your lighting as possible and render to a vrimage that will most certainly help. Any lighting solution that can be precalculated is view-specific, not resolution specific, so you may try rendering those out at a lower resolution, saving those solutions, and loading them up for the final render. This will allow for more memory to be available to the render process, which is at the heart of the issue I believe. It is also good for larger resolutions to render to a VRImage, which basically writes the image bucket by bucket as opposed to at the end of a frame, which frees up even more memory. There's a quick large res tutorial which you can find here which details the process. Also you will need the VRimage to exr converter to work with the vrimage.

[reis0111]

Re: when rendering a large image?

If i understand you correctly dalomar settings used for a low resolution rendering work correctly for a high res rendering?

[dalomar_cg]

Re: when rendering a large image?

I am saying that the lighting solutions will work at any resolution as long as the anything regarding the view is consistent between the resolutions (i.e. the camera position, field of view, and the aspect ratio of the image (focal distance too if DOF is used)). You still will probably want to make sure that your solutions are of the appropriate quality (ie good subdiv and the right min/max rate in IR's case), but even if you left things the same it would work. Does that make more sense?

[reis0111]

Re: when rendering a large image?

Thanks for all the advice dalomar. :Now i have questions about the advice for high res renderings. One is does this vrimage rendering work with the qmc settings? And two quite a few of the terms are different from the tutorial, override rhino, new map mode a few more. Could you point me in the correct direction?

[dalomar_cg]

Re: when rendering a large image?

Well QMC is not a lighting solution that can be saved...its a brute force calculation that is done at render time, where the other light calculations are all varying types of approximations which are precalculated then reconstructed at rendertime (I hope that makes sense). The vrimage as a whole is basically the equivelent of specifying that your output be saved, but with a slightly different process for the save (bucket by bucket as I mentioned before) so there really isn't any required change in your settings to be able to render to vrimage.

The override rhino output thing is simply a way to specify the size of your output through our UI. The map mode is just specifying the way that v-ray will go about its calculations (each one has its own uses) but for the sake of From File mode it just means that it will read the IR or LC info from an external file as opposed to calculating it. You didn't say anything about it, and I haven't mentioned it up until this point (although I believe it is in the tutorial), but the Don't Render Final Image option is important for the precalculations. This simply allows V-Ray to go through rendering out the IR map or LC map, but rather then continue on to rendering the image (which in this case would give you the image at the regular resolution, which you don't want) it doesn't calculate the actual rendering so you can go back and change what you need to.