View Full Version : Photon mapping??

10-24-2003, 08:42 PM
Ok, I just read this article..


This stuff is over my head, but im thinking that photon mapping would be a good thing.. Yes yes?

would that require a complete rewrite or could that be added in?

10-25-2003, 01:17 AM
LightWave's render engine does make limited use of photon mapping, however, it really should be extended to global illumination, and it could also be used for subsurface scattering.

10-25-2003, 03:22 PM
Lightwave is using Photonmapping as EyesClosed wrote. However LW's radiosity doesnt take into consideration the Specularity of surfaces, and caustics have serious limitations.

Right now LW's radiosity emmits plain diffusion. Optionally it considers Volumetrics into the calculation, but it renders slower.
You can disable Volumetric Calculation using the "hidden" command - place it on your menu. It saves a lot of rendering time when GI is ON.

10-28-2003, 03:30 AM
Lightwave is using Photonmapping only in Caustics evaluation, as far as I know!

You can see a test here:

I've used 5 point lights to aim this simple effect... so slow!
Caustics need a major revamp, IMHO!


10-28-2003, 04:16 AM
LW Caustics now are generated on a per light basis.
However this is not enough.

If we consider Backdrop, Reflections, irradiance as bright light sources, Caustics ignore them which is wrong.
I made some experiments with this is mind.

I illuminate a white surface with very bright light, so very bright radiosity is bounced. This radiosity passes through a simple refracting transparent ball. Even though I can see the radiosity crossing the transparent ball, (Diffuse2Specular Transport, which is caustic) this doesnt refract/distort in any way because LW-GI doesnt consider radiosity as part of the caustics calculation.

LW-Caustics now are simplistic per-light effects.

10-28-2003, 04:33 AM

A more simple test...
use Caustics without activating Radiosity and you'll see they work the same:
radiosity ON/OFF doesn't affect the Caustics effect! :(

Strange... I'm agree with Panikos... (just kidding)! ;)


10-28-2003, 05:35 AM
:D heh

12-30-2003, 01:44 PM
Originally posted by Panikos

You can disable Volumetric Calculation using the "hidden" command - place it on your menu. It saves a lot of rendering time when GI is ON.

what is the hidden command? how to use it?

12-30-2003, 05:11 PM
Search in the manual under "Shadow & Light" Chapter.

You can place the Volumetric Radiosity command on your Layout Interface, I suggest under the Lights-Tab, so you can disable it.

Activating it allows the radiosity calculation to include the participating media (All volumetric plugins and volumetric lights)


01-04-2004, 04:42 PM
Lightwave should have ability to connect different renderers..