invalid lightmap sample again

[priad]

A long time without problem with Vray but...
I have invalid lightmap sample in a scene, when I hide a glass mtl I haven't it WHY?
my mtl is made with a vray mtl 100% pure white reflexion with fresnel checked, and 100% pure white in refraction with 1,46 ior.
nothing else, I really don't understand!
Is there RGB value negative in this mtl?
Is pure white a pbl?

[oconv]

what happens if you take 254/254/254 instead of 255/255/255 for reflection (and refraction)?

[jacksc02]

do you have any glossy refractions?

[priad]

yes it works thank's!
But why? I need an explication

[priad]

it works with 254.254.254 in all reflexion refraction.

[Tog]

lightmap doesn't like pure white.

Do not apply perfectly white or very close to white materials to a majority of the objects in the scene, as this will cause excessive render times. This is because the amount of reflected light in the scene will decrease very gradually and the light cache will have to trace longer paths. Also avoid materials that have one of their RGB components set to maximum (255) or above.

[priad]

lightmap doesn't like pure white.

Do not apply perfectly white or very close to white materials to a majority of the objects in the scene, as this will cause excessive render times. This is because the amount of reflected light in the scene will decrease very gradually and the light cache will have to trace longer paths. Also avoid materials that have one of their RGB components set to maximum (255) or above.

Ok time increase but not overbright mtl or invalid lightmap sample! this must added to the list .