vray irradiance map

[Tim Saunders]

it has been a while since i read anything on it, but is seams like i heard something about saving a lowrez irradiance map still gives you good gi calcs for hi rez renders. the result being much faster renders. did i hear that right? whats the procedure if so? i noticed you can select from file to browse for a .vrmap file.

[Geoff]

I tend to use this method when I have a tight deadline too meet.

Check the 'don't render final image' box in the vray global switches rollout

vray irradiance map rollout at the bottom, autosave coose a filename then check switch too save map. same can be with lightcache.

hit render

when its finished uncheck 'don't render final image' box, increase render and then render.

I have rendered a 800x600 irradiance map then 1600x1200 final render ok!

 

Geoff

[JamesTaylor]

Tim,

 

Check out http://www.vray.info i'm sure there is an explanitationon there about this issue, it explains how to calculate the settings, same idea as Geoff uses but but works by adjusting the irridance settings for the final render rather than saving a map 1st

[skogskalle]

yes you can render at half the resolution and get nice quality.... but you can also just change your IRRmap settings with -1, (for example, if your settings for Irradiencemap are -3, -1, just change them to -4,-2). Then you can render at full resolution directly. The results should be the same and take the same amount of time as if rendering at -3,-1 at half resolution. Atleast thats how Ive understood it...

[Tim Saunders]

makes sense to me kalle. if anyone has a dispute with that let us know, because it sure seems like a lot less of a pain.

[jophus14]

Vray explains it the same as you did "Skogskalle." Using your settings for an image at 800X600 image and then decrease the map by -1 to render out a 1600X1200 image. What if you wanna render out an image at 3600X2400, do you decrease your settings to -6,-3 if your oringinal settings for an 800X600 render were -3,0?

[Christopher Nichols]

You guys are all correct... every time you double your res, knock the irradiance map down by 1.

 

Sometimes it is easy to simply do all your test renders at lets say 800x600, then when you find what you like, and you are ready to go to the final high res, save the irradiance map that you have, and render the high res one with the saved map. Not ideal as you generally want to raise the quality of your irr map for the final as well, but it makes things easier. Cool thing is that if you put the IR map on the network, you can use the distributed rendering for it.

[jophus14]

What would be the outcome of using the saved Vbuffer & Irr map for 800X600 and rendering at 5400X3600, then opening the image in Photoshop and printing at 150dpi? Would it be pixelated or as smooth as 800X600 at 72dpi?

[gfa2]

I took a wild stab the other day with a tight deadline and this technique worked pretty good for me. I actually pushed it a little further than what you guys mentioned, but I was pleasantly surprised with the results. I did the first pass to calc the IR at like 800 or 900 pixels wide, then rendered the final image at 4000 pixels wide with the small IR file. And I used 9 PC's via distributed rendering and the image finished in like 45 minutes. I was loving that. I thought I'd be up all night with that thing.

[vansan]

Just use big Min Rate value (-6 or -5) for highres images, so vray will generate less irmap samples with the same visual quality at awesome speed =)