Environment Reflections and Image Plane Rendering

[caustics77]

Hey There,

Last I was here people were so helpful that I've got another question for everyone!

I am doing some basic VRay MTL Wrapper to catch shadows and drop some models on tracked footage and comp later. Everything is setup the way I want but have 2 small issues.

As I said I'll be comping so rendering the background image planes isn't necessary but for testing reasons I'd like it to be there and of correct color. It's apparent the Linear settings aren't applied to my camera's image plane as the attached image has a swatch that is color correct. Is there anything I can do to get it looking like it's supposed to at render time?

Alternately I have a Mirrored Ball unwrapped image I took at the location. I am doing this quick and dirty so I didn't take an HDR it's literally just a JPG for reflections as I test the shot before getting the final model in there. As you can see the reflection is very dark. For this scene I'm using VRay sun and sky, but have disconnected the sky from all the environment variables "BG, GI, Reflect, Refract" and attached my image from the location.



Any help would be fantastic!

Thank you,

-Patrick

[caustics77]

Update, a friend showed me the "Texture Input Gamma". Image plane test render issue solved. Just the environment questions are unanswered, thanks again!

-P

[vlado]

For the reflection strength, what are the settings of the material? Is the "Fresnel reflections" option turned on?

Best regards,
Vlado

[caustics77]

The color is white or .95 in value. The amount is 1.0. Glossiness .97. Fresnel unchecked.

Also, I'm noticing that if I use the Physical Sun and Sky everything is fine, but obviously my reflections aren't real, it's just a gradient. When I break the override reflection connection to the sky node and attach my image this darkening above is what happens. I've tried an 8 bit JPG and a 16 bit PNG, i've even raised the levels in Photoshop, nothing seems to change the chrome-ness of that sphere.

-P

[tashko.zashev]

Hi,

Would it be possible to attach your scene file in order to see the entire setup?

[caustics77]

Absolutely tashko.zashev!

It is available at the link pasted below, it was 49 MB so I uploaded it to my FTP.

http://www.patricksurace.com/transfer/VasquezRocks.zip

Thank you very much!

-Patrick

[tashko.zashev]

Hi, thanks for attaching the file.

The texture that you are using as Reflection environment override doesn't match the overall scene illumination. There are V-Ray Sun and Sky, which are very bright light sources and the V-Ray physical camera is adjusted according to them. So the easiest way to get the reflection looks good is to adjust the file (05.png) node Color gain > Value to ~30 .
*) right click over "Color Gain" > Color chooser

[caustics77]

Pretty solid Tashko. I usually stray from making values super high so I didn't even think of that! Thanks again! I will shoot a real HDR next time with more light info. This was "Lets do this real fast"

V Ray is still so sick!

One thing I can't get my head around though, is my colors will never match? If we up the reflection image to 30, my whites are bright but blacks are washed, is there another solution?

-Patrick

[tashko.zashev]

Hi Patrick,

The colors of the reflections are washed out due to the double gamma applied to the .png image. Linear workflow check box doesn't correct automatically the file nodes added to the environment slots. If you use non linear images, you might have to correct it manually by adding V-Ray texture input gamma attributes.
However, it is better to use .exr or .hdr images for those slots.