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SandmanNinja · April 3rd, 2008

Here are my notes from some tutorials I did recently - I'm at work, so don't have the time to 'clean' it up. hope this makes sense:

Quote:

Logarithmic Exposure Control Parameters
Rendering -> Environment (or press 8) -> Exposure Control -> Logarithmic Exposure Control
Brightness
Contrast
Mid Tones
Physical Scale

[x] Exterior Daylight - tick this if you're using MR Sun
If you don't, then the scene will be VERY over-exposed.
Allows you to continue working with a physically accurate scene

If you use an HDRI, be sure to tick [x] Process Background and Environment Maps

Logarithmic Exposure Control:
[x] Active
[x] Process Background and Environment Maps
[x] Exterior Daylight

If the render is dark, the Physical Scale is probably off.
Physical Scale is measured in candela units.
The typical scene ranges from 80000 to 120000 candela units
This value should be set to the value of the brightest light source (MR Sun, target light, etc)

If a light source emits one candela of luminous intensity uniformly across a solid angle of one steradian, its total luminous flux emitted into that angle is one lumen. Alternatively, an isotropic one-candela light source emits a total luminous flux of exactly 4 / pi lumens. The lumen can be thought of casually as a measure of the total "amount" of visible light in some defined beam or angle, or emitted from some source.

A standard North American 100 watt incandescent light bulb emits approximately 1700 lumens, while a 100 watt sodium vapor lamp emits around 15,000 lumens, about 9 times as much.

Physical Scale goes up to 200,000 units.
Photometric Lights are not affected by physical scale.
They work in a physically accurate scene.

Logarithmic Exposure Control:
[x] Active
[x] Process Background and Environment Maps
[x] Exterior Daylight
[ ] Colour Correction (manually set the white balance in your scene)
[ ] Desaturation Low Levels (in VERY LOW LIGHT scenes, it removes colour like in real life)
[ ] Affect Indirect Only (designed for scanline render engine)

Mid Tones: range from .01 to 20 Default is 1.0 Helps with contrast