I’ve never had good luck with vray when it comes to rendering super high res images, even if the scene is relatively “simple”. I’ve alway run into memory problems, crashes, extremely long render times, etc. Anything above 3000 pixels I cross my fingers.. and anything over 6,000 and I don’t even try to use vray with. Irregardless of weither I am using DR or not. And don’t even think about using displacement at high resolutions!! Although 64 bit may help some of these problems.
I’ve recently had to render an image out at somewhere around 62,000 wide.
I think with 32bit max it won’t let you even try to render anything out bigger than 32,000 or so.
And I think that we had problems even at 32,000. So I believe what we ended up doing is rendering it at 16,000 wide (about 1/4 the final resolution) and using a fractal program to increase the resolution to 32,000 then fractaled it again to 64,000 (seems to work better doing it twice than doing it all at once). End result was that most people aren’t going to be able to tell it wasn’t nativaly rendered at that high of a resolution.
This was all done with the max scanline renderer using split scan lines. And even at 16,000 pixels, I think our machines had a hard time stiching the scans together. We had to do it manually in photoshop. Once it was fractaled up to full resolution.. the final image wouldn’t even fit on a DVD.
My advice if you are going to try to render something that large in Vray is to make sure you only have to render the final ONCE. With the max scan line our scene only took about 30 seconds to render at 800x600.. and at 16,000xwhatever it only took a couple of hours or so. Thus when we had to make changes and revisions to it numorous times even AFTER the “final” rendering.. we knew we could re-render it in just a couple of hours. Even if we could have rendering it in Vray.. I don’t want to think about how many hours/days it would have taken to render, then we wouldn’t have been able to make the requested changes that always come.
Secondly.. be aware that each time you double the resolution you should be able to decrease your Min-rate and Max-rate on your irradiance map by 1 and still end up with the same rendering. So if for example your min rate at 800x600 is -4 and your max rate is -3 and you are happy with the results, and you increase your resolution to 25,600x19,200, you should be able to set your min-rate to -9 and your max rate to -8 get the same result. Although I’ve never tried this with anything that large.
Our image didn’t look as good as it would have with Vray.. but like I said.. I shy away from using Vray with anything that large because of render times/memory problems. There definatly seems to be an expontial increase in render time and possible memory problem crashes as the resolution increases.