VrayNormals under EXR and TIF

[kamel47]

Hi all,

I have a little issue with VrayNormals. When I try to save it different file format give me different results. Please have a look at the example below. The closes to the VFB is the 16-bit Tif but I need the normals as EXR render element. Am I doing something wrong or there is setting in the EXR that I don’t know. Any thoughts are welcome. Thanks.

[ecraft]

Welcome to the world of Gamma. TIFF has all kinds of Gamma and other related issues that I have seen over the years from 3ds max. What does the EXR look like if you add a 2.2 Gamma to it in post? What if you degamma the 32-bit TIFF (gamma 0.45454545)?

-Eric

[vlado]

Which application do you use to view the files? Sometimes applications will automatically apply 2.2 gamma to .exr files for display purposes, so it may look different to the VFB when in fact the actual data is the same.

Best regards,
Vlado

[kamel47]

I wouldn’t blame the TIF because any other file format different than EXR\VRIMG saves it identical to the VFB. I haven setup any gamma to my scene in 3DsMax. I even ask friend to test it under Maya and the result is the same.
I opened the images under Photoshop, After Effects and Nuke. All three applications shows it almost the same.
The archive on the following link have the two file formats: http://artray.co.uk/temp_for_forums/normals.rar

[vlado]

In a multichannel OpenEXR file, the normals element is written as XYZ vector with both negative and positive values - that's why the components are XYZ and not RGB. To get the result as you see it in the VFB, you'll have to multiply the element by 0.5 and add RGB (0.5, 0.5, 0.5) to it (these are normalized colors 0.0-1.0, not 0-255).

Best regards,
Vlado

[kamel47]

Thank you Vlado. Makes a lot of sense now.