Lighting an Exterior Daylight Scene - Photographic Rendering with V-Ray for SketchUp - page 133

Now while the SketchUp type approach produced by the Linear workflow option
does make it much easier for an artist to recreate the same material colors seen in
the viewport in the final renders also, it doesn't actually take into account the way
in which both color and illumination are perceived by humans. You see if we (in real
life) were to look at a grey color that has a diffuse (reflectance) value of 35 percent,
we would perceive something that looks much brighter than a representation of that
color given to us in V-Ray for SketchUp.
This is because the human visual system applies an automatic (logarithmic) bright-
ening or color correction curve to the raw data that it receives. This in turn means we
see the world with much brighter mid-tones than raw data alone suggests we should.
The upshot of all this technical information is that we are now left with a choice as
to how we proceed with our lighting and rendering setup. We could leave the Linear
Workflow option enabled and proceed to work in a technically correct manner. This
would cause our color and illumination values to behave in a very predictable man-
ner, but would at the same time leave colors, especially those found in the mid-tone
range looking unnaturally dark to us.
Or we could instead disable the Linear Workflow option and work with much more
numerically unpredictable shifts in color that will ultimately look and behave in a man-
ner that feels much more natural to us given that this is the way we perceive light to
be working in the real world.
Ultimately, the choice we make regarding our workflow will be up to us. Both options
have strengths and weaknesses inherent in them, in fact the choice we eventually
make could even on occasion be dictated by the type of work that we are doing for
our clients.
In our case, even though we have up to this point been working with this V-Ray for
SketchUp default option enabled, I am going to change things around and use a
workflow that is fairly typical of what I do when working with V-Ray in either 3ds Max
or Maya. To do that, we need to perform the following step:
1. In the options editor Color mapping rollout, uncheck the Linear workflow
option.