The direction matter b/c if you make a real scene with a sunset you don't want to have the sunset on the east side right? or if you create a angular map you don't want to have the sun light on the wrong place, would be not natural, beside the studio light what is everything allowed..
If i take a picture for the background I have to know what is direction of the sun so I can set up good the specular and sun light too.. it is very important, mixing the directions will not match good the HDR IBL together.. pple forget that what they see in the mirror ball is what we don't see in the scene at all, and it is mirrored picture that why the confusion about the directions, I made this mistake 2 years ago, but until today I made a very good research about and many many tests .. and one more time again, standing with the face to the south, the west would be always on the right side..and east on the left... that why the model in the factory state scenes always have the face to the south..

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