Vray Sky? - background problems

[pshupe68]

I'm having a problem with my background. I would like to have a gradient map show up, which I have in my Environment slot. I have a VraySun set up. Do I have to also apply a Vray sky as well? I tried putting a VraySky material in my background, with the same result. I get a completely black background even when I change my background color to white?? Where is this set?? Thanks in advance. Here are my settings for render/VraySun/Environment and result. Any input appreciated.

Regards Peter.

[studioDIM]

http://www.chaosgroup.com/forum/phpB...ic.php?t=17824

Have a go, it'll tell you what's going on.

Lele

[pshupe68]

Thanks will do! Cheers Peter.

[Dynedain]

uncheck affect background in the color mapping options

[studioDIM]

That won't affect the reflections...
It's a case of Camera exposure, and general balance.
He'd still have to multiply the BG until it gets visible under these lighting/exposure conditions, and at that point he'd like to have "affect background" on.

Lele

[Da_elf]

my guess is to increase the output on the background image

[pshupe68]

Unchecking affect background worked. I have downloaded the tutorial movies that Lele suggested. Thanks for the advice.

Regards Peter.

[studioDIM]

Unchecking affect background worked.

Do your reflections show the change, as well?
Here the method doesn't work for anything else than returning the BG at its un-exposed values, but it doesn't do so for its reflections of it.
Hence those remain as dark as the BG was when exposed.

Lele

[pshupe68]

Studiodim - I didn't see any change in reflection. So I guess they are still reflecting the black BG. I am trying to get a chance to view your movies from the first response to my post. I am holding off until I get a chance to review. Thanks a lot for the link and I am looking forward to viewing them. Also thanks to everyone else for the suggestions.

REgards Peter.

[Da_elf]

the trick is nt use the that "affect background" option what you need to do is put your gradient into an output map and raise the output amount. the reflections didnt change because they are not "background" they are a reflection of the dark background

[studioDIM]

Yes, indeed, Elf.
The tutorial explains how to measure by how much, precisely, to raise the output.
Should empower a user with the knowledge needed to react to these issues when they arise, no matter under which circumstance.

Lele

[Da_elf]

usually i dont bother measuring. i just take an average guess (hide my objects) then render. if the sky looks decent. then good by my

[studioDIM]

Agreed, but that requires a certain confidence that not everyone has in the first place.
Having a colorpick fix it for good can be of help to some (it is to me, so my BG doesn't overdo the GI, for instance, or blows reflections away.) Everything that's above 1.0 float is invisible, so you could have a white BG at 255 white, but in reality it's multiplier is a LOT higher.
No colorpick, in the case, no joy.

Lele

[pshupe68]

I have viewed the tutorial. I tried to duplicate the results. I setup my plane object with Vray material, white - 255, Vray camera with default settings, and Vray sun with default settings. I also setup my standard camera, standard direct light for sun.

When I render and use my color picker for the Standard camera and light I get the correct results. When I render with my VraySun, Vray camera, I get different results than noted in the tutorials. I tried to set the settings as noted in the tutorial. Noteably the gamma under prefences and the similar settings in the vray render settings.

Results attached. Notice I have 3 different color pick examples. The reason is that they are substantially different from different areas of the plane. In the standard render they were all the same?? Also they are not 380x larger than the standard?? Please advise.
Note- GI is disabled as in the tutorial. The picks were all taken on the plane, not in the sky.

I will continue to review the tutorial and check my settings. Thanks.

Regards Peter

[studioDIM]

vignetting is on in the camera exposure...
It darkens the corners of your image a bit.

Also make sure (but that might not be the issue in your case) that the sun is perfectly perpendicular to the plane.
Snapping to grid helps in that case.

Also, the physcam settings are not as the ones in the tutorial, namely f-number is twice the one i use, and the shutter speed is set to 1/125 and not 1/30.

Hope it sorts it.

Lele