Isotropic phase function about exposure-render HOT 2 OPEN

This is in fact correct.

You could check the lambertian shader in PBRT, which is quite similar to an 
isotropic phase function, except that in stead of 2 * PI, the phase function 
envelopes 4 * PI.

Cheers,

Thomas

Ah, thank you very much for your reply.

Unfortunately I currently have no access to pbrt, but I would be glad if you 
could spend a sentence or two to help me understand this.

I am a little confused that the "Isotropicphase.F" is anything but 
isotropic. And furthermore there is allready a "lambertian.F".

And in case of a lambertian.F, shouldn't be the pdf be halfed e.g. use the 
cos term as well?

Sorry for this messy question, I would be glad if you would reply.

Thank you,

Christoph