www.kraytracing.com

hi everyone -

I just ran into these vray renders : http://saluto3d.blogspot.com/2007/10/blog-post_15.html

And I was taken by the realism achieved, they mentioned "light portals" in the original posts that linked to that site, so I am wondering :

- is it possible to use these "light portals" in kray and how would they work?

any ideas?

thanks !

Matt -

I'ts highest on my wish list since it will improve both speed and quality quite alot in almost any situation. Grzegorz is coding on portals right now so i eagerly waits to test it.

awesome !

glad to see development is fast and furious lately..

Im glad I decided to bet my chips on kray+lw instead of moving to c4d+vray and re-learning everything again.

go Kray !

What are these "light portals"? Could you post link about it as the site on the above link was in Russian.
Thanks

Lightportals or skyportals is a common name for a "helper object" that can "guide" the photons to where they make most sense.
If you bombard a house with photons only a handfull of them will actually get into the windows and enter the room. If you put Skyportals in the windows acting as targets for the photonemitters they will guide the photons into the room where they make more sense. Skyportals guidefunctionality can be used everywhere when you want to tell the renderer where the important stuff is.

Thanks Silverw. Managed to find info on it on the net. As I understand one will need to provide extra geometry to define portals. This sounds promissing as it could aid in lighting those difficult interiors.

sepo wrote:As I understand one will need to provide extra geometry to define portals

Or you could just assign the glass geometry in external windows as skyports

Skyports are going to give a hugh boost to render times in photomap mode, can't wait
(not as much as Sliver though )

True , but if you have the courtyard situation than you need to add extra geometry to make it leak proof.
Looking forward myself

Yes
me too wait for this.
Skyportal make good shadows and lights, it easy to use.
But Skyportal must be optymize include Kray (V-ray have very speed Vraylights)

Yes, I had no clue what the link said, I tried altavista translator but didnt make any sense.

I will do some research to see how they work to get my mind used to the idea once we have it in Kray

Matt -

Also, it would be nice to have an "exit portal" style capability for direct raytraced luminous surfaces. To explain, they would work exactly like a normal directly-raytraced luminous surface, except the color of light "cast" by the surface would depend on the direction of the incoming ray (generally using the background color), allowing a polygon to cast light as if it was a window out into space instead of a flat surface.

Trying to use Kray on a scene with small windows and trying to light it with an HDRI environment has been a little frustrating. Photon mapping+FG was taking a relatively long time with blotchy results (fast compared to native LW of course), and making a partial skydome set to be luminous and directly traced was also slow and grainy. When I gave up and made the glass in the windows luminous and set their color to be the average of the light that would otherwise have come from the HDRI environment, renders are turning out much smoother much faster. A directly-traced "exit portal" or "window" shader would be really useful in a case like this.

FYI, I had been able to hack this functionality into LW's own render engine by putting an area light behind a transparent polygon with a custom node tree that would tint the shadows that polygon cast depending on the angle.

Thanx for that input weepul. The Skyportals we plan should be possible to add to any surface visible for the camera or not.

_mats_ wrote:awesome !

glad to see development is fast and furious lately..

Im glad I decided to bet my chips on kray+lw instead of moving to c4d+vray and re-learning everything again.

go Kray !

I didn't plan on leaving LW, but I'm glad I bet my chips on Kray as well. It seems like Grzegorz & the guys are very enthusiastic about their work and this plug-in.

Just to make sure I'm being clear, since I didn't yet know enough about Kray to use the right terms in my previous post in this thread:

I'd like to see a "window material" shader that can be applied to luminous polygons that act as lumilights. These lumilights would cast different color and intensity light depending on angle, like light coming through a window from an environment.

Photon-guiding exit portals would be really cool too since I discovered that Photonmap mode (as opposed to Lightmap) is really great for interiors with mostly direct, but diffuse, lighting.

Work on skyportals are going well is all i can say at the moment