skylight portal problem

[matteo_speri]

Hello everybody,
I am Matteo and I am studying vray 5; I have a problem:
when i use vray sun / sky i read that you have to use portal lights to bring the light inside;
I am attaching an example image..when I create a portal light I cannot activate the skylight portal function..what am I wrong?

i am doing some tests to understand if it is better vray sun + sky + portal light or just hdri with vray dome.
Thanks for your help
Matteo

[^Lele^]

You do not need portals at all, anymore.
Put the GI environment (your HDRI, or Sky map) in a dome light and that's all you'll ever need.

[matteo_speri]

thanks for the advice lele;
so you say that if i use vray sun + sky (no hdri), i also use vray dome with the sky?

[^Lele^]

so you say that if i use vray sun + sky (no hdri), i also use vray dome with the sky?

Exactly.

The dome light provides for two optimisations: the first is called "Importance Sampling", and it's done on the map (so, an HDRI or a VraySky, f.e.) plugged into it.
It helps finding the brightest areas of the map, which contribute the most to your scene's lighting, so to sample those the most instead of wasting computations on dark, less useful areas.
This optimisation is quite common across most renderers, Corona has it embedded in the environment map, f.e., Arnold and rMan both have a dome light fixture.

The other optimisation is unique to V-Ray (to the best of my knowledge.), and it's the Adaptive Dome technology, which allows for accurate sampling of the dome (and its textures) within your 3d Scene, without the need for you to guide it with light portals.

Most of the time, you'll want the GI to come from a dome, and use the rest of the overrides to drive the visible background, if you'd like it to be different from the one providing for your lighting (i.e. use a dome to light, and a flat image as camera-visible background.)

[matteo_speri]

excellent thank you you were really kind ..
i am learning and studying the various lighting systems of vray and now it is all clear
Ciao Lele

[^Lele^]

excellent thank you you were really kind ..

You're very welcome.

i am learning and studying the various lighting systems of vray and now it is all clear

For area lights, remember to check out the vraySoftBox texture.
It can help with visible sources to avoid jagged edges (the "frame" section) and in general help with shaping the lighting coming from your all-too-flat area sources.

Ciao Lele

A presto!

[trick]

You do not need portals at all, anymore....

I am having a scene with an interior and an exterior, lit by an adaptive dome. The camera is in the interior and have my light balanced for the exterior. Now I want the light "streaming" from the windows into the interior so at the windows the ceiling and walls get more highlighted. With portals I could tune this very easily by changing the diffuse and specular multipliers, without affecting the exterior lighting. So now I have to place extra VRayLights to simulate portals and forcing more light into the interior. This is not easier than before. Or is there a better way? Just to be clear: I am not striving for realism, just control.

[^Lele^]

I am having a scene with an interior and an exterior, lit by an adaptive dome. The camera is in the interior and have my light balanced for the exterior. Now I want the light "streaming" from the windows into the interior so at the windows the ceiling and walls get more highlighted. With portals I could tune this very easily by changing the diffuse and specular multipliers, without affecting the exterior lighting. So now I have to place extra VRayLights to simulate portals and forcing more light into the interior. This is not easier than before. Or is there a better way? Just to be clear: I am not striving for realism, just control.

That's a misquote: the user was looking for portals to bring light in, to achieve realism hitherto impossible without portals guiding the light, hence my reply.
For your case, you can also make a duplicate of your dome, and use include/exclude to have it light just the interior, so that you're free to multiply the intensities at will.

[glorybound]

For me, exposure is the key. I use a good HDRI, expose the interior, and I expose the exterior in post-production. If you are rendering RAW, all the information is there to use in PS. I mask my glass and adjust the exposure.

[trick]

...For your case, you can also make a duplicate of your dome, and use include/exclude to have it light just the interior, so that you're free to multiply the intensities at will.

That way I would need to keep including interior objects when setting up the scene. But maybe just including walls, floor and ceiling will be enough. That way I wouldn't have to set up fake portals. I know the quote was not really applicable, but I couldn't find a direct solution and this thread came close.

BTW: is there a big difference using VRayLights as they are now without the portal option compared to the old ones?

[^Lele^]

That way I would need to keep including interior objects when setting up the scene.

Indeed, a nuisance. Hopefully selection sets and such will help.

I know the quote was not really applicable, but I couldn't find a direct solution and this thread came close.

No harm meant, none done.
I was being pedantic for anyone else bumping in the thread.

BTW: is there a big difference using VRayLights as they are now without the portal option compared to the old ones?

In what way?

[trick]

...In what way?

Didn't old portals "see" objects outside blocking the light rays? And since activating portal disabled some features (like light multiplier, etc.), maybe the light direction is different?

[^Lele^]

Non-portal lights have directionality, but if not using that, i wouldn't think the light distribution should change from a portal light.
However, i'd need to test this: so much time has passed since i used a portal, so i may be talking nonsense.

[trick]

For me, exposure is the key...

With small projects (1-2 interiors) I do too, but I currently have a few projects with LOTS of interiors. With some review rounds I really want to keep postwork initially to a minimum.

[glorybound]

You can always drop a second HDRI intensity way down and have the main one invisible.