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HairyBouy
03-16-2006, 06:19 PM
Hey there chaps,
We have a number of shots with flaming torches hanging on walls of sets. rendering times of using Hyper Voxels is a 45 min frame. deadline is to near for that....

We have tried rendering out the flames by themselves with a separate alpha channel and placing them on an image plane, but the result is a much duller flame, about 20% the brightness.

maybe i'm doing something wrong? anyone got tips or tutes to render our scenes faster?

thanks guys

HB

faulknermano
03-16-2006, 07:03 PM
We have tried rendering out the flames by themselves with a separate alpha channel and placing them on an image plane, but the result is a much duller flame, about 20% the brightness.

it could be the luminosity of the image map. it should be set to 100 or more, and its diffuse at a lower value.

jeremyhardin
03-16-2006, 07:04 PM
well, if you want to use those planes, you could use Additive Transparency (in the advanced tab of the surface editor.)

It makes the object act like it's screened over the render. any RGB value above 0 will be added to the color behind it.

fgreen
03-23-2006, 03:28 PM
Are you using particles or lights for the fire? In my experience, using volumetric lights for the fire renders faster than the HV on particles.

The pre-HV method is to use several cones inside each other. On each one apply turblence with an envelope in the position to both the color and transparency. Also use a yellow, orange, red gradent for the color and set the input to distance from pivot or distance along an axis (to get the color to change as the fire goes up). Experiment with the speed of the positional envelopes to get the right effect. You can also apply the edge transparency shader and use a gradient in the transparency channel, also using distance to pivot. Providing the pivot is at the bottom of the fire, this will cause it to become more transparent at the top of the flames. Combined with the edge transparency shader it provides a nice soft-edged firey effect.

I currently am using this effect in an animation for jet afterburners. It looks pretty convincing and renders very fast. I know I've seen tutorials on this technique, but can't remember where. If you need it let me know, I will zip and try to attach the scene file in a posting.