Is there a way to animate an hdri file to gain light intensity (from night to day)?
not that Im aware of. You could try mixing two hdris, one for night and one for day and then animating the difference.
I think..
I think paul Debevec has just completed this experiment with the parthenon, capturing HDRI FILM to use like a complete day circle illumination..
it was then been investigated thoroughly in SIGGRAPH 2004
Check his site, you might find something usefull there ..
http://www.debevec.org/Parthenon/film.html
yeah Im sure HE can do it. No doubt if you took multiple shots throughout the day you could interpolate between them
I was just thinking if i had control over the material multiplier in an animation. on frame 1 it’s 00.2 on frame 50 it’s 2.00.
other than moving a light around, is the only other way to raise and lower light levels is with an video file? (I think I need to go back an do a little reading)
I think you could, but dont know how realistic it would look.
i would assume an ifl file can be used for an image sequence of HDRI files.
EDIT
just checked and since vray hdri map doesnt have time controles like a normal bitmap file then i doubt its possible
percy,
this is my ignorance showing through but do you mean when you say animate the difference, that you animate a daylight scene (with meshes and the lot) and then animate a night scene and then in a video editer mix them together or is there a way to just animate the hdri?
val
well no, I meant if it was possible, put the day and night hdri map into a mix map, and animate the mix spinner. Like I said wouldn’t work too well, but if you dont have an animated map showing the difference luminance throughout the day, then Im not sure how effectively it could be done.
I have a little tiny quicktime that shows this. I’ve used it effectively in the self illumination channel of a standard material. It doesn’t work in a VRayLightMtl though. No HDR but just animate a VRay light in front of it.
http://mywebpages.comcast.net/jonathan.reynolds/tmp/sky1.mov
220kb PLEASE RIGHT CLICK AND DOWNLOAD!!!
Wish I could remember where it came from. Think it was some sort of technical light research site.
--Jon
wow very nice! any chance of sharing a larger version of it? 
Actually what Paul debevec did is very simple in fact, you can do it too, if you have a full day to dedicate to it… or have some interns. Simply use a very high quality digital camera with a fisheye lense, and take a full dynamic range set of images (20 or so stops) every 15 mins, 30 mins, or hour depending on how fast you want the thing to move. Compile each set with a HDRShop, and make a frame sequence out of it… you’re done.
wow very nice! any chance of sharing a larger version of it?
Sorry bro, I only found it this small. I searched for the page but couldn’t locate it again. I’m rerendering an older test with it now and I’ll post that in a sec.
I bet we could try to recreate it with gradient maps or in combustion.
Here is the low quality test but damn, I had my output Gama set wrong so it’s a little dark in the shadows.
http://www.dtoxx.com/J\_Bug/TimeLightTest\_03.avi
--Jon
Actually what Paul debevec did is very simple in fact, you can do it too, if you have a full day to dedicate to it… or have some interns. Simply use a very high quality digital camera with a fisheye lense, and take a full dynamic range set of images (20 or so stops) every 15 mins, 30 mins, or hour depending on how fast you want the thing to move. Compile each set with a HDRShop, and make a frame sequence out of it… you’re done.
ummm… thats what I said… only not so eloquently or succintly. 
actually. why not do an animated sky using terragen and the HDRI output. cant wait for the new terragen their new cloud generator looks awsome.
with the sequence of HDRI files there should be some way to have them strung together into an image sequence if someone can figure it out.
Take a look at IFL in the max help file. That should do the trick.
--Jon
i know about the ifl. it was me who suggested it somewhere in the middle of this post. however problem is the vray HDRI map doesnt have a time section.
HA! I figured it out! or I think (I haven’t rendered it out as an animation yet) It’'s really simple. I made a large sphere, made the material a hdr file and set it to .2, made the material double sided, put everything inside it. then went and turned on auto key slid the frames up and then moved the hdri multiplier up to 1.00. then slid it back down to the first frame without touching the multiplier and it rendered out at .2.
hehe, I thought that method was obvious. If your just using it for GI, then it might look okay. But if your using it for reflection, then its not really going to look like a movie of the day progressing.
he he, nothing is obvious to me. I’m thick as a brick and max is all brand new to me. I’ll have to play with the reflections and see what you mean. here’s my test file.
http://home.midsouth.rr.com/valgardson/nflower.mov
640 by 480 339kb file