VrayLightDome bug in refraction

[kagemaru]

I've noticed a bug in vraylight when used as a dome: basically when set as invisible, refraction rays consider not the entire spherical part (full dome option), but always just the upper hemisphere, even less.
You can easily reproduce this by having a completely refractive object, a dome light mapped with a texture, checked as invisible and set to spherical (it's more visible if you set it full dome): you'll notice that it will refract just the upper side of the texture (while working perfectly with reflection and diffuse rays).
Cheers,

fede

[Zdravko]

Which V-Ray version are you using? We can not reproduce the issue in our environment. Maybe there is something else in the scene or in the HDRI file.
Would it be possible to attach an example scene or send it to: support@chaosgroup.com

[kagemaru]

I'm using a nightly build version, not a very recent one cause it's on the farm now. It is dated 30th november 2012.
Could this be already fixed?
I'll attach a sample scene (i used a gradient instead of a texture in the dome light, the bug is still there in my renders), if you check invisible you'll get different results.





dome_light_bug.zip

[pjkw]

Never seen this before but its still there in nightly build 2.45.01, it doesnt seem to be related to the texture (untextured is the same result) and not really related to the full dome option either as you still see more in refraction when enabling full dome than without it enabled. Its there in 1.5 aswell!

[Zdravko]

Please note that the refraction is bound with the visibility option of the V-Ray light.
When the light is set to invisible it doesn't affect the refraction as well, that is why you get only the reflections.

[kagemaru]

Please note that the refraction is bound with the visibility option of the V-Ray light.
When the light is set to invisible it doesn't affect the refraction as well, that is why you get only the reflections.

Even if it doesn't make much sense to me, it isn't really the situation here since i stil get some refraction when set to invisible.
Would it be possible to at least have the possibility to choose whenever see it in camera, reflection and refraction rays?

[Zdravko]

it isn't really the situation here since i stil get some refraction when set to invisible.

What you see in the teapot are only refractions, you can check that if you disable Affect reflections option in the dome light and render. The you will get totally black image (without reflection and refraction).
Also could you please let us know in which situation you will need a separate Affect Refraction option, so I can forward your request to the developers?

[kagemaru]

What you see in the teapot are only refractions, you can check that if you disable Affect reflections option in the dome light and render. The you will get totally black image (without reflection and refraction).
Also could you please let us know in which situation you will need a separate Affect Refraction option, so I can forward your request to the developers?

How can that be possible if my shader has not a reflection component, just refraction?
Speaking of request, in my opinion i would expect the light refraction visibility connected to the reflection one, and not to the visibility option.
This is why i said that, if not possible (because of some technical issues), it would be nice to at least have the possibility to choose.
I came across this problem when rendering cars with transparent glasses.

[vlado]

This is not a bug as such; you are seeing the dome light in the internal reflections inside the teapot. It can be argued what would be the correct behavior in this case. For the moment, I've made a note to implement a separate "Affect refractions" option to avoid this ambiguity.

Best regards,
Vlado

[kagemaru]

This is not a bug as such; you are seeing the dome light in the internal reflections inside the teapot. It can be argued what would be the correct behavior in this case. For the moment, I've made a note to implement a separate "Affect refractions" option to avoid this ambiguity.

Best regards,
Vlado

Gotcha.
Thanks again guys.

[Zdravko]

How can that be possible if my shader has not a reflection component, just refraction?

If we follow the rays that goes through the teapot: some of them gets refracted, goes out of the object and hits the background (when you have invisible option enabled) they gives us a black color.
Nevertheless some of the rays gets reflected from the inner surface due to the wide hit angle and IOR of the material. Those internal rays are treated as a reflection. Therefore they show the color of the Dome Light.
Anyway we have added your request for a separate option "Affect Refractions" in our "to do" list.
For now to workaround the issue you can exclude the teapot from the light.

Thank you for your feedback.