Sensor

The Sensor section of the UVR Camera Settings component defines the actual sensor behaviour :

  • The Compute Polarization field of the sensor defines whether the polarization should be computed or not. You should always favour a polarized sensor as it ensures the polarization is taken into account in the render. You should only use a non-polarized sensor if you have memory issues,

  • The Type defines the sensor behaviour.


Predict Engine supports 5 types of sensor :

Human

In order to visualize a scene as the human eye would perceive it, the CIE (Commission Internationale de l'Eclairage) has defined several standard "observers" that represent the color perception of an average person. This sensor converts the raw spectral radiance to the CIE XYZ color space using these observers.


The observers are characterized by 3 curves commonly named the Color Matching Function (CMF). We use this CMF to convert the spectral radiance to the XYZ color space. After an XYZ to RGB conversion, the resulting image corresponds to what an average person would see.

We offer a choice between some commonly used CMF :

  • CIE 1931 2° standard observer,

  • CIE 1964 10° standard observer,

  • CIE 2015 2° standard observer,

  • CIE 2015 10° standard observer.

Figure A : comparison of the perceived colors of a color checker using a CIE 1931 observer (left), a CIE 1964 observer (middle), and a CIE 2015 observer (right).

Still Camera

This sensor behaves like the CCD or CMOS sensor of a classic camera. The sensor computes a raw image using the camera’s spectral response curves. The raw image is then converted to a LDR image in the post pipeline function. Be aware that the RGB values do not correspond to any physical quantity as it depends on the post pipeline.


This is the sensor you should use to model a measured sensor.


The sensor requires an RGB spectral response file. You can use a default preset or an actual measurement of a sensor. The measurement should be stored in an *.xml file that contains the integration curve of each type of pixel in the sensor. The file should be constructed as follow :

<observer>

<entry wavelength="550" r="0.2" g="0.8" b="0.0" />

<entry wavelength="XXX" r="XXX" g="XXX" b="XXX />

...

</observer>

with the wavelength in nanometers.

Luminancemeter

This sensor converts the raw spectral radiance to the CIE XYZ color space and displays the Y component : the luminance in cd/m².


In order to visualize a scene as the human eye would perceive it, the CIE (Commission Internationale de l'Eclairage) has defined several standard "observers" that represent the color perception of an average person. These observers are characterized by 3 curves commonly named the Color Matching Function (CMF). We use this CMF to convert the spectral radiance to the XYZ color space.

We offer a choice between some commonly used CMF :

  • CIE 1931 2° standard observer,

  • CIE 1964 10° standard observer,

  • CIE 2015 2° standard observer,

  • CIE 2015 10° standard observer.

Spectroradiometer

This sensor computes the radiance of the light integrated over each spectral band in W/m²/sr. The sensor is defined by its spectrum range (its range of detection) and the number of spectral bands in this range.

Polarimeter

This sensor computes the different components of the light’s polarization state, the image contains the four components (S0, S1, S2 and S3) of the Stokes vector. See the polarization section for more details on polarization.

Additional sensor settings are available if you enable the Expert Mode.