VraySun and Vraylight skyportal....

[victorwol]

Hi! I'm not totally sure I understand what is the point of using skyportals with the vraysun? Make Vray calculate only rays coming from that side instead from all around? I see also that there is an option on the VraySky environment to select the vraysun used, what for? And when you specify a node then it seems like the parameters you change in the light does not affect anymore anything and the settings on the VraySky are the ones one need to change??

[vlado]

Hi! I'm not totally sure I understand what is the point of using skyportals with the vraysun?

The portals help to get skylight into the scene, not sunlight. The sun has a very well defined direction and V-Ray can "find" it easly. Finding the skylight through (small) windows is more difficult, which is why we have the skylight portals.

I see also that there is an option on the VraySky environment to select the vraysun used, what for?

Some people like to use a Directional light instead of the VRaySun.

And when you specify a node then it seems like the parameters you change in the light does not affect anymore anything and the settings on the VraySky are the ones one need to change??

This is correct, yes. The idea being, that if you choose a Directional light, it does not have any of the sky parameters.

Best regards,
Vlado

[victorwol]

I see.... Directional light works with the standard MAX volumetric lights which are very fast, sunlight seems to not work with it... any plans to make a fast volumetric effect that works with your lights? something that might not need to respond to caustics and can do a fast job?

Also, even if I only have one window right in front of a sun light, adding the sky portal seems to give me a cleaner GI.

[tricky]

So if we set up a daylight system with a vray sun and a vray sky, but also create skylight portals just outside the windows (for an interior scene), am I right in thinking that vray still calculates the skylight as normal, but it increases the quality/definition' just where the skylight portals are?

[vlado]

So if we set up a daylight system with a vray sun and a vray sky, but also create skylight portals just outside the windows (for an interior scene), am I right in thinking that vray still calculates the skylight as normal, but it increases the quality/definition' just where the skylight portals are?

You can think of the portals like that, yes. In practice they are area lights that take their color from whatever is behind them (which usually happens to be the sky, but in fact can be anything else, f.e. a self-illuminated object or just a difficult part of the scene).

Best regards,
Vlado

[tricky]

So should we turn off (?) the vraysky for interior scenes using a daylight system? Would that be faster/cleaner?

[vlado]

So should we turn off (?) the vraysky for interior scenes using a daylight system? Would that be faster/cleaner?

No, you still need the vraysky to compute the actual sky color. The portals are just an optimization for your scene to guide V-Ray to the windows, they don't replace the environment color.

Best regards,
Vlado

[tricky]

Many thanks vlado

[victorwol]

very good info.

Thanks!