Glowing negative shadows

[rcollett]

So we use the VRay Sun-Sky combination a lot to light our outdoor scenes, but many times the VRay physical cam is not convenient to use. Rendering from a perspective viewport to test materials or models results in a blown out scene, so we typically scale back the lighting so that we can use standard cameras. An intensity value of 0.02 is a good rough value. We have noticed some problems with using a reduced value in past scenes, for example the sky renders out way too dark, and pre-rigged lights designed for the physical cam are way to bright and need scaling down. I was thinking that instead of reducing the intensity of the sun, that we could modify the Bright Multiplier in the Color Mapping section. We actually rendered a few projects with the Bright Multiplier method and it worked out fairly well. I just tried this approach on my current project and got a surprise. Anyone seen this glowing negative shadow effect before? Here's three renders: (in case it's not obvious, the problem is with the third image, under the bridge)

VRay Sun 1.0, VRay Physical Cam, Bright Mult 1.0


VRay Sun 0.02, Standard Cam, Bright Mult 1.0


VRay Sun 1.0, Standard Cam, Bright Mult 0.02


VRay 1.50 SP5
Adaptive DMC 1 3
Light Cache 1000
Irradiance -3 -1, 20 Hsph, 30 Interp

[Morne]

I dont have an answer to your current problem.

But, but with VRay 2.0 you can render a perspective view and still use your correct vraysun and vraycamera settings. It has a exposure control for viewports and standard cameras, to name just 1 cool new feature. Maybe consider upgrading in the near future? This will solve many of your issues with messing with sun intensity and multipliers etc

[pixela]

Instead of decreasing the light intensity, you can activate Vray Exposure Control and render any viewport without any problem.

[vlado]

You need to change both the bright and dark multipliers; if you reduce just the bright multiplier, you might get color inversion (which is in fact, what you are getting). Another option is to use Reinhard color mapping - then you only need to change the single multiplier value.

Best regards,
Vlado