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  1. #41
    Originally Posted by bit biter View Post
    Meaning, in my case, that the albedo values were way to high. After a while I noticed and realized: "My (pbr) materials appear to have a way to strong specular reflections now". Even with the default specular setting of the principled shader. It's look way to strong. Any idea what I should do?
    I am a far cry from an albedo expert. I would suggest trying to roughly match recorded and known albedo values. If you are colouring (aka non-achromatic ratios of RGB albedo) a surface, aim to have the value average to the albedo value expressed as a luminance ratio. The weightings are roughly 0.2126 red, 0.7152 green, and 0.0722 blue. That is, when you multiply those weights by your RGB triplet, they should sum to the approximate albedo value I believe.



  2. #42
    Member J_the_Ninja's Avatar
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    Originally Posted by bit biter View Post
    Since I prefer to use the Filmic view for a while now, I learned first that I had to use more correct albedo values. Meaning, in my case, that the albedo values were way to high. After a while I noticed and realized: "My (pbr) materials appear to have a way to strong specular reflections now". Even with the default specular setting of the principled shader. It's look way to strong. Any idea what I should do? For example in Cynicat's pro shaders I can use grey instead of white in the glossy shader. (lower the value of the specular reflection)
    The principled shader's specular weighting is based on real light interactions. If it's too strong, you may actually have too low of roughness. Also, pay attention to objects around you - a lot of things are shinier than you might think at first. For example, if you ask "is asphalt matte?" most people would say "yes!". But if asphalt is matte, how does this happen? http://3.bp.blogspot.com/-9HPn5qPF3u...0/IMGP0609.JPG

    A lot of things get very shiny if viewed at a grazing angle with a bright light hitting them. Just something you need to get used to when lighting. If it's too much of a problem, the "specular" slider on the principled shader can reduce the reflections by pulling back the IOR of the surface.



  3. #43
    Originally Posted by J_the_Ninja View Post
    A lot of things get very shiny if viewed at a grazing angle with a bright light hitting them. Just something you need to get used to when lighting. If it's too much of a problem, the "specular" slider on the principled shader can reduce the reflections by pulling back the IOR of the surface.
    Worth noting that opaque, breakup, or semi-transparent / translucent gobos are a huge aid here as well. Doubly so when you can make them invisible to camera.



  4. #44
    Don't have examples with me to post right now, but I've figured out how to transform between color spaces with matrix transforms in OCIO and use the provided LUTs for the transfer function (both normally and inverted). This does lead to a question though about the following:

    Originally Posted by troy_s View Post
    Essentially you have to take the transfer function of the encoded footage and decode it
    Say my example has a Cineon transfer function. Once I know that, is there a way to decode that in OCIO without a LUT? Or are LUTs the one and only way to do this (in OCIO or other ways)? If so, do I need to figure out how to make LUTs in order to properly decode the transfer function of any footage/still that doesn't have one provided already?

    Also, does it matter what order these operations (transfer function, matrix transform) are performed in? I've been going in the order of transfer function then matrix transforms, but haven't tried the other way around yet.



  5. #45
    Originally Posted by Mandalorian View Post
    Don't have examples with me to post right now, but I've figured out how to transform between color spaces with matrix transforms in OCIO and use the provided LUTs for the transfer function
    Remember that transforming primaries needs to have identical white point colours as well. Also consider that this may, or may not, lead down the path of gamut mapping.

    Originally Posted by Mandalorian View Post
    Say my example has a Cineon transfer function. Once I know that, is there a way to decode that in OCIO without a LUT? Or are LUTs the one and only way to do this (in OCIO or other ways)? If so, do I need to figure out how to make LUTs in order to properly decode the transfer function of any footage/still that doesn't have one provided already?
    You will need a LUT. 4096 for a 1D is sufficient, with a shaper if required. A 65x65x65 cube is sufficient for 3D LUTs. There is discussion to add in expression handling, but that is not currently available.

    For Cineon, there is an existing LUT available via the ACES repository.

    Originally Posted by Mandalorian View Post
    Also, does it matter what order these operations (transfer function, matrix transform) are performed in? I've been going in the order of transfer function then matrix transforms, but haven't tried the other way around yet.
    Matrix transforms for colour spaces must be done on linear sources, otherwise the linear algebra will fall apart. So it is always transfer function to linearise the source, then RGB to XYZ, then XYZ to RGB. The two matrices can of course be concatenated. Again, make sure you match the white points via a Bradford or like adaptation matrix.



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