Creating a Camera Sensor in Photometric/Colorimetric Mode

This page shows how to create a Camera Sensor using the Photometric/Colorimetric mode. This mode allows you to set every parameter of the camera sensor including spectral definition.

To create a Camera Sensor using the Photometric/Colorimetric Mode:

  1. From the Light Simulation tab, click System > Camera .
  2. From the Mode drop-down list, select Photometric/Colorimetric to enable the advanced definition.
  3. 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.
  4. Define the Axis System of the camera sensor in the 3D view by clicking to select an origin, X to select a line and Y to select a line or click and select a coordinate system to autofill the Axis System.
    Important: Make sure the sensor is not tangent to a geometry.
    Note: Depending on which camera model is described in the .OPTDistortion input file, the origin of the sensor is different.
    • If the .OPTDistortion file is based on the Basic Distortion Curve model (v1 version), the origin corresponds to the Entrance Pupil Point (EPP) of the camera.
    • If the .OPTDistortion file is based on the Speos Lens System model (v2 version), the origin corresponds to the center of the sensor.
    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.
    If you need to adjust the axes orientation, use Reverse direction on one or both axes.
  5. If you want to create a dynamic inverse simulation:
    1. in the Acquisition section, define the Integration time needed to get the data acquired by one row of pixels.
    2. in the Acquisition section, define the Lag time, if you want to create a rolling shutter effect in the result.
      Note: For more information on the acquisition parameters, refer to Acquisition Parameters.
    3. in the Trajectory file field, click Browse to load a trajectory file (*.json), if you want to define a moving camera sensor.

      The trajectory describes the different positions and orientations of features in time. The Trajectory file is used to simulate dynamic objects.

      Note: For more information on trajectory files, refer to Trajectory File.
      When a trajectory file is assigned to a Camera sensor and the feature is edited, the trajectory is displayed in the 3D view.
    For more information on the dynamic Inverse simulations capabilities and how to set them, refer to Dynamic Inverse Simulation.
  6. In the Optics section, define all the parameters of the camera:
    Note: According to the *.OPTDistortion file model used as input of the Camera, the Optics section provides you with different parameters.

    For more information on which parameter is available, refer to Understanding Camera Sensor Parameters.

    Note: Horizontal/vertical fields of view set to 0 are not supported and may generate incorrect result. If the values are set to 0, refresh the Camera sensor feature.
    1. In Focal length, adjust the distance between the center of the optical system and the sensor (in mm).
    2. In Imager distance, you can adjust the distance between the aperture and the sensor.
      Note: Imager distance does not affect the results. Changing it is only used for visualization purposes and does not represent the real sensor.
    3. In F-number, type the size of the aperture of the camera's front lens.
      Note: The smaller the number, the larger the aperture.

      The irradiance is calculated from the radiance by using an acceptance cone for the light (the cone base is the pupil).

      More details about the F-number can be found here.

    4. In Transmittance, click Browse to load a .spectrum file. The spectrum file defines the amount of light that passes through the lens to reach the sensor
    5. In Distortion, click Browse to load an .OPTDistortion file.
      The *.OPTDistortion file is a file that contains information on the camera and is used to introduce/replicate the behavior of the camera lens.
      A preview of the camera sensor system appears in the 3D view.
  7. Define the sensor's size and resolution:
    1. Define the number of horizontal and vertical pixels corresponding to the camera resolution.
      Note: Speos supports a maximum resolution of 23170 * 23170 pixels.
    2. Define the sensor's height and width.
  8. From the Color mode drop-down list, define the sensor's color management:

    • Select Monochrome to define a sensor with one channel.

      The sensitivity section is displayed and allows you to define a spectrum file for the sensor's channel.

    • Select Color to define the sensor as a RGBcamera.

      The sensitivity section is displayed and allows you to define a spectrum file for each of the three sensing channels.

      Note: With the Color mode, the simulations results are available in color according to the White Balance Mode.
  9. If needed, adjust the Gamma correction.
  10. From the White balance mode drop-down list, choose which correction to apply to get true whites:
    • Select None to apply no correction and realize a basic conversion from spectral results to RGB picture.
    • Select Grey world to apply a coefficient on each channel to get the same average for the three channels.

    • Select User white balance to use the grey world method and manually type the coefficients to apply.

      In the Sensor white balance section, adjust the coefficients for Red, Green and Blue colors.

    • Select Display primaries to display the results and the colors as they are perceived by the camera.

      In the Sensor white balance section, click Browse to load a .spectrum file for each color.

  11. In PNG bits, select the number of bits used to encode a pixel.
  12. Adjust the sensor sensitivity:

    • If you selected the Color mode, import a .spectrum files per color.

    • If you selected the Monochrome mode, import one .spectrum file.

  13. In Wavelength, define the spectral range of the sensor:
    • Edit the Start (minimum wavelength) and End (maximum wavelength) values to determine the wavelength range to be considered by the sensor.

    • 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.

  14. If you want to adjust the preview of the sensor, click Optional or advanced settings :
    1. Activate or deactivate the preview of certain parts of the system by setting them to True/False.

      Display pupil is available only for the model V1.

      Display object field is not supported in case of a binary distortion file.

    2. Adjust the Visualization radius.
The Camera Sensor is created and visible in Speos tree and in the 3D view.