Forum: Bryce


Subject: Reason for so many volumetric lights

vangogh opened this issue on Feb 24, 2006 ยท 8 posts


vangogh posted Fri, 24 February 2006 at 1:15 PM

Attached Link: http://www.renderosity.com/viewed.ez?galleryid=1163788&Start=1&Artist=vangogh&ByArtist=Yes

Since I posted my latest image I have had two comments asking why I used so many volumetric lights to achieve the light rays effect. the answer is that it was the only way out of several dozens of attempts that I tried that seemed to work the way I wanted. Lighting has always been my Achllies Heel and always seems to drive my up a wall no matter what type of scene I am working on, but this one in particular took alot of time and sweat to achieve. first I tried using one parallel light directed through the window from the outside. This one worked sort of kind of, once I realized that the sun had to be disabled before the rays would be visible. But I couldn't have cast shadows and or receive shadows enabled (in the materials lab window) because either the light rays were broken up or else the areas where the window dividers should have blocked the light rays weren't there. And if I had shadows enabled in the light lab then the rays would disappear altogether. I ended up trying so many different combinations in either the light lab and the materials lab that I soon became frustrated and went to bed with a troubled mind that night. At around 4 am I awoke with a start and another idea to try. why not have 2 lights - one for the rays and another separate one to cast the desired shadows on the floor. This worked great up to a point. I had shadows being cast correctly on the floor and also light rays that were unbroken without strange shadows being cast on the rays themselves. But there was still no indication of the rays being interupted by the window dividers like there should have been. Then I had another sleep interupting idea to try putting one light just big enough to shine through one pane only and then dup that light 10 times and put one behind each pane so that the dividers would appear to be blocking the rays correctly. As for render time, surprisingly, there was very little difference between using just one volumetric light and using 10. The volumetric material used was the default one assigned by the light lab when selecting the volumetric option. this is the solution that worked for me. I would love to hear about any other ways that anyone else has found to work for them.