How to create a anisotropic bsdf file#
This tutorial demonstrates how to create bsdf file using pyspeos
What is a BSDF#
BSDF stands for Bidirectional Scattering Distribution Function, which is a mathematical function that characterizes how light is scattered from a surface. In Speos we have two models to represent BSDF data: Spectral BSDF(.brdf) and Anisotropic BSDF (.anisotropicbsdf). The first allows for each wavelength to store a full bsdf description with this it allows for great color representation. the second uses spectral modulation to represent the color but allows for anisotropic behaviour by taking a BSDF for each anistropic angle. Both formats need an interpolation between incident/anistropic angles and wavelength In many cases the data comes from measurements and need coordinate transformations to be used
Prerequisites#
Perform imports#
[1]:
from pathlib import Path
import numpy as np
from ansys.speos.core import Speos
from ansys.speos.core.bsdf import AnisotropicBSDF, BxdfDatapoint
from ansys.speos.core.launcher import launch_local_speos_rpc_server
from ansys.speos.core.speos import SpeosClient
Define constants#
Constants help ensure consistency and avoid repetition throughout the example.
[2]:
HOSTNAME = "localhost"
GRPC_PORT = 50098 # Be sure the Speos GRPC Server has been started on this port.
USE_DOCKER = True # Set to False if you're running this example locally as a Notebook.
Define helper functions#
[3]:
def clean_all_dbs(speos_client: SpeosClient):
"""Clean all database entries of a current SpeosRPC client.
Parameters
----------
speos_client : ansys.speos.core.kernel.client.SpeosClient
SpeosRPC server client
Returns
-------
None
"""
for item in (
speos_client.jobs().list()
+ speos_client.scenes().list()
+ speos_client.simulation_templates().list()
+ speos_client.sensor_templates().list()
+ speos_client.source_templates().list()
+ speos_client.intensity_templates().list()
+ speos_client.spectrums().list()
+ speos_client.vop_templates().list()
+ speos_client.sop_templates().list()
+ speos_client.parts().list()
+ speos_client.bodies().list()
+ speos_client.faces().list()
):
item.delete()
[4]:
def create_lambertian_bsdf(is_brdf, nb_theta=5, nb_phi=5):
"""
Create a lambertian Distribution as np.array.
Parameters
----------
is_brdf: bool
True if generating brdf data, False btdf data
nb_theta: int
number of theta samplings
nb_phi: int
number of phi samplings
Returns
-------
theta: np.array,
shape (nb_theta, 3)
phi: np.array,
shape (nb_phi, 3)
brdf: np.array,
shape (nb_theta, nb_phi)
"""
thetas = np.zeros(nb_theta)
phis = np.zeros(nb_phi)
bxdf = np.zeros((nb_theta, nb_phi))
if is_brdf:
for t in range(nb_theta):
thetas[t] = t * np.pi * 0.5 / (nb_theta - 1)
for p in range(nb_phi):
phis[p] = p * 2 * np.pi / (nb_phi - 1)
bxdf[t, p] = np.cos(thetas[t]) / np.pi
else:
for t in range(nb_theta):
thetas[t] = np.pi * 0.5 * (1 + t / (nb_theta - 1))
for p in range(nb_phi):
phis[p] = p * 2 * np.pi / (nb_phi - 1)
return thetas, phis, bxdf
[5]:
def create_spectrum(value, w_start=380.0, w_end=780.0, w_step=10):
"""
Create a spectrum for a bsdf.
Parameters
----------
value: float
spectrum value
w_start: float
wavelength start
w_end: float
wavelength end
w_step: int
wavelength sampling number
Returns
-------
spectrum: np.array,
"""
spectrum = np.zeros((2, w_step))
for w in range(w_step):
spectrum[0, w] = w_start + w * (w_end - w_start) / (w_step - 1)
spectrum[1, w] = value
return spectrum
Model Setup#
Load assets#
The assets used to run this example are available in the PySpeos repository on GitHub.
Note: Make sure you have downloaded simulation assets and set
assets_data_pathto point to the assets folder.
[6]:
if USE_DOCKER: # Running on the remote server.
assets_data_path = Path("/app") / "assets"
else:
assets_data_path = Path("/path/to/your/download/assets/directory")
Create Anisotropic BSDF from datapoints#
To create and save a bsdf we need to first create a connection to the SpeosRPC server ### Connect to the RPC Server This Python client connects to a server where the Speos engine is running as a service. In this example, the server and client are the same machine. The launch_local_speos_rpc_method can be used to start a local instance of the service.
[7]:
if USE_DOCKER:
speos = Speos(host=HOSTNAME, port=GRPC_PORT)
else:
speos = launch_local_speos_rpc_server(port=GRPC_PORT)
Create a BXDFDatapoint#
to create a bsdf we need the bsdf for multiple incident angles. In this example we assume the color doesn’t change over the icnident angles so we can use anisotropic bsdf and we assume the data has no anisotropy
[8]:
clean_all_dbs(speos.client) # clean all the database entries
incident_angles = [np.radians(5), np.radians(25), np.radians(45), np.radians(65), np.radians(85)]
all_brdfs = []
for inc in incident_angles:
thetas, phis, brdf = create_lambertian_bsdf(True)
all_brdfs.append(BxdfDatapoint(True, inc, thetas, phis, brdf))
print(all_brdfs[0])
{'anisotropy': 0, 'bxdf': array([[3.18309886e-01, 3.18309886e-01, 3.18309886e-01, 3.18309886e-01,
3.18309886e-01],
[2.94079989e-01, 2.94079989e-01, 2.94079989e-01, 2.94079989e-01,
2.94079989e-01],
[2.25079079e-01, 2.25079079e-01, 2.25079079e-01, 2.25079079e-01,
2.25079079e-01],
[1.21811920e-01, 1.21811920e-01, 1.21811920e-01, 1.21811920e-01,
1.21811920e-01],
[1.94908592e-17, 1.94908592e-17, 1.94908592e-17, 1.94908592e-17,
1.94908592e-17]]), 'is_brdf': True, 'incident_angle': np.float64(0.08726646259971647), 'theta_values': array([0. , 0.39269908, 0.78539816, 1.17809725, 1.57079633]), 'phi_values': array([0. , 1.57079633, 3.14159265, 4.71238898, 6.28318531])}
Create Anistropic BSDF class instance#
[9]:
new_bsdf = AnisotropicBSDF(speos)
new_bsdf.description = "PySpeos BSDF Example"
new_bsdf.anisotropy_vector = [1, 0, 0]
Create Spectrum with 80% reflectivity
[10]:
spectrum = create_spectrum(0.8)
Assign reflection spectrum to bsdf
[11]:
new_bsdf.has_reflection = True
new_bsdf.spectrum_incidence = np.radians(0)
new_bsdf.spectrum_anisotropy = np.radians(0)
new_bsdf.reflection_spectrum = spectrum
Assign brdf data
[12]:
new_bsdf.brdf = all_brdfs
save_path = assets_data_path / "example_bsdf.anisotropicbsdf"
new_bsdf.save(save_path)
print(new_bsdf)
{'has_transmission': False, 'has_reflection': True, 'brdf': [<ansys.speos.core.bsdf.BxdfDatapoint object at 0x7f66a771e4d0>, <ansys.speos.core.bsdf.BxdfDatapoint object at 0x7f66a771e4a0>, <ansys.speos.core.bsdf.BxdfDatapoint object at 0x7f66a771e5c0>, <ansys.speos.core.bsdf.BxdfDatapoint object at 0x7f66a771e530>, <ansys.speos.core.bsdf.BxdfDatapoint object at 0x7f66a771e560>], 'btdf': None, 'nb_incidents': [5, 0], 'incident_angles': [[np.float64(0.08726646259971647), np.float64(0.4363323129985824), np.float64(0.7853981633974483), np.float64(1.1344640137963142), np.float64(1.4835298641951802)], []], 'interpolation_settings': None, 'anisotropic_angles': [[0], []], 'spectrum_incidence': [np.float64(0.0), 0], 'spectrum_anisotropy': [np.float64(0.0), 0], 'reflection_spectrum': array([[380. , 424.44444444, 468.88888889, 513.33333333,
557.77777778, 602.22222222, 646.66666667, 691.11111111,
735.55555556, 780. ],
[ 0.8 , 0.8 , 0.8 , 0.8 ,
0.8 , 0.8 , 0.8 , 0.8 ,
0.8 , 0.8 ]]), 'transmission_spectrum': None}
BSDF Interpolation Enhancement#
This section shows:
How to apply automatic interpolation settings and save a post-processed bsdf file.
How to change interpolation settings, apply the new settings to bsdf, and save the post-processed file
How to re-load a bsdf file has interpolation enhanced and retrieve the interpolation settings.
[13]:
print(
new_bsdf.interpolation_settings
) # user can check if there was interpolation settings, here is None
new_bsdf.create_interpolation_enhancement(index_1=1.0, index_2=1.4)
print(new_bsdf.interpolation_settings) # Now interpolation settings is not None
new_bsdf.save(file_path=assets_data_path / "example_bsdf_automatic_interpolation.anisotropicbsdf")
None
<ansys.speos.core.bsdf.InterpolationEnhancement object at 0x7f66a775b8e0>
[13]:
PosixPath('/app/assets/example_bsdf_automatic_interpolation.anisotropicbsdf')
Apply user defined interpolation enhancement
[14]:
interpolation_settings = new_bsdf.create_interpolation_enhancement(index_1=1.0, index_2=1.4)
interpolation_settings_reflection = (
interpolation_settings.get_reflection_interpolation_settings
) # return as fixed dictionary, user cannot add/remove item
print(interpolation_settings_reflection)
{'0': {'0.08726646259971647': {'half_angle': 1.5533430342749535, 'height': 0.3141551883034776}, '0.4363323129985824': {'half_angle': 1.5533430342749535, 'height': 0.3141551883034776}, '0.7853981633974483': {'half_angle': 1.5533430342749535, 'height': 0.3141551883034776}, '1.1344640137963142': {'half_angle': 1.5533430342749535, 'height': 0.3141551883034776}, '1.4835298641951802': {'half_angle': 1.5533430342749535, 'height': 0.3141551883034776}}}
Change interpolation settings
[15]:
interpolation_settings_reflection["0"][str(np.radians(5))]["half_angle"] = 0.523
interpolation_settings_reflection["0"][str(np.radians(5))]["height"] = 0.5
Set the changed interpolation settings back to bsdf file and save
[16]:
interpolation_settings.set_interpolation_settings(
is_brdf=True, settings=interpolation_settings_reflection
)
new_bsdf.save(file_path=assets_data_path / "example_bsdf_user_interpolation.anisotropicbsdf")
[16]:
PosixPath('/app/assets/example_bsdf_user_interpolation.anisotropicbsdf')
Load a bsdf file with interpolation enhanced
[17]:
clean_all_dbs(speos.client)
saved_bsdf = AnisotropicBSDF(
speos=speos, file_path=assets_data_path / "example_bsdf_user_interpolation.anisotropicbsdf"
)
print(
saved_bsdf.interpolation_settings
) # here an InterpolationEnhancement Class object is returned
previous_settings = saved_bsdf.interpolation_settings
print(
previous_settings.get_reflection_interpolation_settings
) # user can review the previous settings
previous_settings = saved_bsdf.create_interpolation_enhancement(index_1=1.0, index_2=1.4)
print(
previous_settings.get_reflection_interpolation_settings
) # with same index values, user use create_interpolation_enhancement to create a new settings
<ansys.speos.core.bsdf.InterpolationEnhancement object at 0x7f66a7739630>
{'0.0': {'0.08726646259971647': {'half_angle': 0.523, 'height': 0.5}, '0.4363323129985824': {'half_angle': 1.5533430342749535, 'height': 0.3141551883034776}, '0.7853981633974483': {'half_angle': 1.5533430342749535, 'height': 0.3141551883034776}, '1.1344640137963142': {'half_angle': 1.5533430342749535, 'height': 0.3141551883034776}, '1.4835298641951802': {'half_angle': 1.5533430342749535, 'height': 0.3141551883034776}}}
{'0.0': {'0.08726646259971647': {'half_angle': 1.5533430342749535, 'height': 0.3141551883034776}, '0.4363323129985824': {'half_angle': 1.5533430342749535, 'height': 0.3141551883034776}, '0.7853981633974483': {'half_angle': 1.5533430342749535, 'height': 0.3141551883034776}, '1.1344640137963142': {'half_angle': 1.5533430342749535, 'height': 0.3141551883034776}, '1.4835298641951802': {'half_angle': 1.5533430342749535, 'height': 0.3141551883034776}}}
Defined new interpolation settings for an already enhanced bsdf file
[18]:
previous_settings_diff_index = saved_bsdf.create_interpolation_enhancement(index_1=1.0, index_2=1.5)
print(
previous_settings.get_reflection_interpolation_settings
) # with different index values, a new automatic settings is returned
{'0.0': {'0.08726646259971647': {'half_angle': 1.5533430342749535, 'height': 0.3141551883034776}, '0.4363323129985824': {'half_angle': 1.5533430342749535, 'height': 0.3141551883034776}, '0.7853981633974483': {'half_angle': 1.5533430342749535, 'height': 0.3141551883034776}, '1.1344640137963142': {'half_angle': 1.5533430342749535, 'height': 0.3141551883034776}, '1.4835298641951802': {'half_angle': 1.5533430342749535, 'height': 0.3141551883034776}}}
[19]:
speos.close()
[19]:
True