Vray Dome Light Issue

[frankhellner]

Hi,

 

I have followed all settings from a number of online tutorials on Dome light HDRI in vray and rhino. I don't know what it is, some of the renders have a black (darkened) part near the top of the image, and some don't (depends on the perspective) - please see attached images. For these two scenes, I didn't touch the domelight at all, only moved around and showed a different view, already they showed 2 different results.

There are some scenes that I need to show a particular perspective of a building, (perspectives where the camera is near the ground, not bird eyes view) and those scenes always have that darkened part at the top. Has anyone encountered this problem? I have tried many things, and I can't seem to figure it out. I am using Vray 1.5 and Rhino 5

 

Many thanks

Edited August 31, 2015 by frankhellner

[Francisco Penaloza]

I am not a Rhino user, but I can tell you the problem is the lack of background in your scene, your environment it is black and that is what your glass material is showing/reflecting. in 3DMax V Ray dome overwrite the environment, showing the same image that you use to lit your scene as a background. maybe in Rhino you need to do an extra step for this.

 

Some exposure adjustment it is recommended for your image, now everything look very over exposed.

[frankhellner]

Thanks for your reply. This is only my test model. I have a very complicated model that it takes too long to do these test renders. I purposely did not put in a background so I can clearly see the HDRI image with Dome light. All the tutorials I watched online did not start with a background, they used the image in the domelight.

[timothyhanson]

Francisco is correct, refraction by it's very nature needs something to refract for you to see its values. Your second image is refracting the ground which is clearly visible beneath the glass, but in your first image it is refracting the black void behind. If you think about it, unless there is a color value to the fog parameter of the refraction all any glass or water material has to use for it to be visible is what it can reflect or refract from the environment around it.