Rendering using Radiance_As Beginners - SPOT Pro released

Hi Ikrima,

Answers below:

Regarding SPOT Pro, it seems that it can work out annual simulation for CFS

with BSDF but for grid points we still need to use command-line (as you

SPOT does automatically calculate a workplane level (height can be
specified) grid of points. In you query it sounded like maybe you were
interested in possible other illuminance points (eye level or wall) for
which you may need to go behind the scenes and work with classic Radiance.

Also, we still need to use command-line (radiance) to generate BSDF that
will be used with SPOT Pro . Is that right?

BSDF files can come from several places: 1) there is a small library of
generic ones in SPOT. 2) You can generate them via genBSDF and command
lines. 3) LBL's Window 7.3 program can generate them 4) If small enough
samples you can have physical goniophotometer measurements that would need
to be converted to the Radiance BSDF format 5) use companies like mine, we
offer daylighting performance characterization and BSDF creation for
complex optical daylight systems as service.

Also, what is the difference between SPOT Pro and Daysim tools in terms of

accuracy and flexibility (as both using Radiance engine)?

They both use Radiance for all simulation they just have two different
approaches to annual simulation. DAYSIM uses Daylight Coefficients,
breaking the sky into atleast 145 patches and calculating the contribution
from each and then using this data to simulate throughout the year. 1, 2, 3
and 5phase methods all just treat the sun and sky components in different
ways. SPOT interpolates from a range of design day calculations to
simulate throughout the year. In my opinion both have some advantages and
disadvantages in terms of accuracy and speed and how they can treat window
treatments. The annual comparison's I have seen show very similar results
between the two methods but I do feel more annual daylighting simulation
studies and validation is needed of all methods in general.




Zack Rogers, P.E., LEED AP BD+C
Daylighting Innovations, LLC
808 S. Public Road, Suite 200
Lafayette, CO 80026