Image based lighting (IBL) light source

[Micha_cg]

Today I have seen at the Vray help page, that Vray support a IBL light source. The example looks great - sharp shadows from a HDRI. Could be nice for VfR too.

http://www.spot3d.com/vray/help/150R...les_lights.htm

Did somebody use it at 3dsmax? What's the experience?

[dalomar_cg]

Re: Image based lighting (IBL) light source

...Umm I'm not really sure what your asking for because vfr already supports IBL (all those hdrs you use for your environments). There are only 2 things in regards to IBL that vfmax has that we don't. First is a light dome, which is nothing different then having an HDR for your environment, except that its a little easier to adjust the rotation (the actual position of the dome doesn't affect the outcome). The other is the ability to map a texture to a rec light.

[Micha_cg]

Re: Image based lighting (IBL) light source

If I understand right, there is a big difference between a HDRI at the environment and an IBL light. The dome light is a raytraced light like an arealight. So, the shadow quality is not dependent from the GI method. The dome light seems to support subdivs like standard lights.



The advantage could be, that high contrast HDRIs produce nice sharp shadows and maybe the dome light works without GI too. Try to use a HDRI with a high intesity sun - you will not be happy. But an IBL dome light will based on importance sampling ...

The V-Ray dome light has been extended to support arbitrary texture maps that determine the amount of light coming from each direction on the virtual dome hemisphere. V-Ray then uses importance sampling to trace more rays in the directions where most of the light is coming from. This ensures speed and quality that were never before possible with pure gathering GI methods.


* Easy setup for image-based lighting (IBL);
* Importance sampling of the dome texture for fast and clean results;
* Support for photon mapping for fast and accurate caustic effects.

I'm curious, how to use a light source like this.

[dalomar_cg]

Re: Image based lighting (IBL) light source

I read through Spot 3d a little more and I see the difference now. Ultimately it comes down to sampling. Because the Image Based lights are sampled in much the same way as regular lights are, it allows the result to be more reliable, less dependent on GI quality, and have additional capabilities that are not possible with GI (mainly photon support and direct light tracing).

[Micha_cg]

Re: Image based lighting (IBL) light source

Is it on the wish list now?

[dalomar_cg]

Re: Image based lighting (IBL) light source

I've been wanting to get the option to map textures to rec lights for a while. As for the dome option that depends on whether its in the SDK. I'll see what Joe says.