Hi!

1) I am using the transdata material for incorporating measured

BTDF's [1/sr] in Radiance. With the help of 'rtrace', I will verify the

results. Is it possible to compute luminance values with 'rtrace'?

2) In the Radiance Digest I have found a formula for the metdata

material:

radiance (watts/sr/m^2) Lo = spec * cos(theta_i) * omega_i * Li * f

where:

f = BTDF in 1/sr

mega_i = solid angle of source in sr

Li = avg. radiance of source in watts/sr/m^2

theta_i = angle between surface normal and source direction

spec = multiplier for specular component from material arguments

I would like to calculate the luminance values back to the

measured BTDF's using the transdata formula. How can I get the

transdata formula?

3) Another question concerns the diffuse sky component. How will

Radiance compute this component with the transdata material?

Could anybody answer my questions or give me reference how I

can solve these problems?

Best regards,

Frank