How to parse and query a tabulated BSDF file (.xml)

Pyradiance BSDF object provides a host of methods for parsing and analyzing a tabulated BSDF file. See sectons below for examples. You can instantiate a BSDF object by giving the file path to the BSDF (.xml) file.

You can either plainly instantiate the object like so:

import pyradiance as pr
sd = pr.BSDF("bsdf.xml")

You can also instantiate the BSDF object in a context manager, which will clear for you the memory associated with the loaded BSDF once done:

with pr.BSDF('bsdf.xml') as sd:
    ...

Basic information

A BSDF object has two attribtues desecribing basic information about the BSDF: info and components. Here is an example of accessing the information:

with pr.BSDF('bsdf.xml') as sd:
    info  = sd.info
    cp = sd.components

Here are the results:

>>> print(info)
Materials: Name
Manufacturer: Manufacturer
Width x Height x Thickness (m): 0.0 x 0.0 x 0.0
Has geometry: no
>>> print(cp)
Peak front hemispherical reflectance: 0.48338043257526025
Peak front hemispherical transmittance: 0.09124324694247694
Diffuse front reflectance: (0.3883772003721621, 0.3883772003721621, 0.3883771656485355)
Diffuse back reflectance: (0, 0, 0)
Diffuse front transmittance: (0, 0, 0)
Diffuse back transmittance: (0, 0, 0)

Direct hemispherical values

with pr.BSDF("bsdf.xml") as sd:
    sd.direct_hemi(0, 0, 't')  # direct hemispherical transmittance at theta=0°, phi=0°
    sd.direct_hemi(30, 0, 'r')  # direct hemispherical reflectance at theta=30°, phi=0°
    sd.direct_hemi(40, 45, 'ts')  # direct - direct transmittance at theta=45°, phi=45°

Querying the projected solid angle given an incident angle

You can query the scattering solid angle of a given incident direction. Here is an example of query and minimum and maximum solid angle at normal incidence.

with pr.BSDF('bsdf.xml') as sd:
    min, max = sd.size(0, 0)

You can also specify the outgoing angle as well and, as a result, the minimum and maximum angle will be the same.

with pr.BSDF('bsdf.xml') as sd:
    min, max = sd.size(0, 0, t2=180, p2=0)

Evaluating the BSDF given an incident and outgoing angle

You can also explicitly evaulate the BSDF at a given incident and outgoing angle.

Here is an example of evaluating a BSDF with an incident theta=30°, phi=45° and outgoing theta=145°, phi=90°.

with pr.BSDF('bsdf.xml') as sd:
    sval = sd.eval(30, 45, 145, 90)

Generating random scattering samples given an incident direction

You can generate N random scattering sample given an incident direction. You'd also need to specify the type of the hemispherical values.

Here is an example of generating 10 transmittance samples with an incident theta=30°, phi=45°.

with pr.BSDF("bsdf.mxl") as sd:
    vecs, clrs = sd.samples(30, 45, 10, 't')