Creating a Radiance Sensor Observer Type

This page shows how to create a Radiance Sensor that computes and analyzes radiance (in watt/m2) and luminance (in candela/m2) distribution. The radiance sensor described is created from the point of view of an observer.

To create a Radiance Sensor Observer Type:

  1. From the Light Simulation tab, click Radiance .
    The sensor appears in the 3D view and is placed on the origin of the assembly.
  2. In General, from the Definition from drop-down list, select Observer.
  3. From the Type drop-down list:

    • Select Photometric if you want the sensor to consider the visible spectrum and get the results in cd/m2 or lm/sr/m2.

      Note: In case of a photometric result generation, the International Commission on Illumination (CIE) defines the visible spectrum as follows: "There are no precise limits for the spectral range of visible radiation since they depend upon the amount of radiant flux reaching the retina and the responsivity of the observer. The lower limit is generally taken between 360 nm and 400 nm and the upper limit between 760 nm and 830 nm".

    • Select Radiometric if you want the sensor to consider the entire spectrum and get the results in W/sr/m2.

      Note: With both Photometric and Radiometric types, the illuminance levels are displayed with a false color and you cannot make any spectral or color analysis on the results.

    • Select Colorimetric to get the color results without any spectral data or layer separation (in cd/m2 or W/sr/m2).

    • Select Spectral to get the color results and spectral data separated by wavelength (in cd/m2 or W/sr/m2).

      Note: Spectral results take more time to compute as they contain more information.
  4. From the Layer drop-down list:

    • Select None to get the simulation's results in one layer.

    • Select Source if you have created more than one source and want to include one layer per active source in the result.

      Tip: You can change the source's power or spectrum with the Virtual Lighting Controller in the Virtual Photometric Lab or in the Virtual Human Vision Lab.

    • Select Face to include one layer per surface selected in the result.

      Tip: Separating the result by face is useful when working on a reflector analysis.

      • In the 3D view click and select the contributing faces you want to include for layer separation.

        Tip: Select a group (Named Selection) to separate the result with one layer for all the faces contained in the group.
      • Select the filtering mode to use to store the results (*.xmp):

      • Last Impact: with this mode, the ray is integrated in the layer of the last hit surface before hitting the sensor.
      • Intersected one time: with this mode, the ray is integrated in the layer of the last hit selected surface if the surface has been selected as a contributing face or the ray intersects it at least one time.

    • Select Sequence to include one layer per sequence in the result.

      • Define the Maximum number of sequences to calculate.
      • Define the sequences per Geometries or Faces.
      Note: Separating the result by sequence is useful if you want to make a Stray Light Analysis. For more information, refer to Stray Light Analysis.
  5. In Focal, define the distance between the sensor plane and the observer point.
  6. If needed, adjust the Integration angle in case you add your Radiance sensor to a Direct simulation.
  7. In the 3D view, Set the Axis System of the sensor by placing one point and two directions in the scene:
    1. In the 3D view, click and select one point to place the observer point in the scene.
    2. In the 3D view, click and select a line to define the Front direction (corresponding by default to Z axis).
    3. In the 3D view, click and select a line to define the Top direction (corresponding by default to Y axis).
    4. or click and select a coordinate system to autofill the Axis System.
    Important: Make sure the sensor is not tangent to a geometry.
    Note: Make sure no geometry intersects the sensor. Otherwise you may generate unexpected black result in CPU simulation.
    Tip: To adjust the sensor position and orientation dynamically from the 3D view, you can also use the Move option (Design tab).
    Note: If you define manually one axis only, the other axis is automatically (and randomly) calculated by Speos in the 3D view. However, the other axis in the Definition panel may not correspond to the axis in the 3D view. Please refer to the axis in the 3D view.
  8. If you want to use an XMP Template to define the sensor, in XMP Template, click Browse to load an .xmp file.

    An XMP Template is an .xml file generated from an XMP result. It contains data and information related to the options of the XMP result (dimensions, type, wavelength and display properties).

    When using an XMP Template, measures are then automatically created in the new .xmp generated during the simulation based on the data contained in the template file.

    • If you want to inherit the dimensions of the sensor from the XMP Template file, set Dimensions from file to True.

      The dimensions are inherited from the file and cannot be edited from the definition panel.

    • If you want to define the radiance sensor according to display settings (grid, scale etc.) of the XMP Template, set Display properties from file to True.
  9. In Horizontal field of view and Vertical field of view:
    1. Define the field of view of the sensor
      Tip: You can either use the manipulators of the 3D view to adjust the sensor or directly edit the values from the definition panel.
    2. Adjust the sampling of the sensor.

      The sampling corresponds to the number of pixels of the XMP map.

      The Central resolution is automatically calculated and depends on the Sampling value.

      The Central resolution is the central angular resolution which corresponds to the angular resolution of the pixel located in front of the observer.

  10. If you selected Spectral or Colorimetric as sensor type, set the spectral excursion to use for simulation.
    1. Edit the Start (minimum wavelength) and End (maximum wavelength) values to determine the wavelength range to be considered by the sensor.
    2. If needed, in Sampling, adjust the number of wavelengths to be computed during simulation.
      The Resolution is automatically computed according to the sampling and wavelength start and end values.
  11. In Optional or advanced settings , to display the sensor grid in the 3D view, set Show grid to True.
The Radiance Sensor is created and appears in Speos tree and in the 3D view.