Physical sun issue

[kubbek]

Rendering with physical sun and sky gives me very washed out result where shadows from the sun are barely visible. I render similar settings with v-ray for rhino (it is not exact comparison as it probably has another sky model) where shadows are very dark and defined. Similar effects are achieved in modo renderer. Is there something wrong with physical sun in v-ray for modo or some settings? I just set modo environment to physically based daylight and a directional light to physical sun.

All best,
Jakub

[chadstevens]

Is your camera's exposure set correctly?

[kubbek]

Is your camera's exposure set correctly?

Yes it is. It is either dark or overexposed but shadows are always washed out.

[chadstevens]

I'm not familiar with Modo, but this sounds like a gamma issue if it's not the exposure.

[vladimir.nedev]

When you set a directional light to Physical Sun, it won't actually turn into a V-Ray Sun. This will happen only when you have added the V-Ray Sun/Sky package to the directional light.
That's probably the reason for the washed out shadows in your case, the light from the sun (actually not sun, but directional light) is very dim ( it uses the Radiant Exitance parameter).
I might have done it like that, because in the V-Ray core there is no option to clamp the sun intensity, so it will get very bright if I export it as a V-Ray Sun.

I will change this, it is very counter-intuitive like this.
For now, try adding the V-Ray Sun/Sky package to your directional light, and see if you can achieve the results you expect.

Greetings,
Vladimir Nedev

[kubbek]

Yes it is working now but I agree that it is not very intuitive.

Best,
Jakub

[vladimir.nedev]

So, this is fixed in the nightly build from 2016.02.04. You will no longer have to add the V-Ray Sun/Sky package to a Directional light to turn it into a V-Ray Sun.
It will be enough to enable the Physical Sun check-box.

Also I fixed a bug where the sun shadows could not be disabled using the Shadow Type parameter.

So to summarize, doing any of these things will turn a Directional light into a V-Ray Sun :
- enabling Physical Sun check-box
- adding a V-Ray Sun/Sky package to it

When a Directional light is turned into a V-Ray Sun, the Radiant Exitance parameter is no longer used and you will most likely need to use a V-Ray Physical Camera as well.
When a V-Ray Physical Camera is used, the clamping of the sky will be automatically disabled.

Also, when a Directional light has the V-Ray Sun/Sky package, any Environment material connected to it will use the Ground Albedo and Size Multiplier from the V-Ray Sun/Sky package.
If the package is not present, the MODO channels for these parameters in the Environment material will be used. Not really sure if that's the best behavior. It has worked like that since the beginning.

Greetings,
Vladimir Nedev