Understanding the Physical Camera Parameters

The following page helps you understanding how to define and use the different components of a Physical Camera sensor.

Speos Light Box

The Speos Light Box contains all the geometries related to the lens system (lenses, opto-mechanics, etc.) of the camera to be simulated.

Warning: All geometries included in the Speos Light Box of a Physical Camera are considered as part of the sensor. That means, like every sensor, it has no impact on the light propagation. If you are willing to add a specific geometry in the project having an impact on the propagation, you must add it in the list of geometries of the simulation and you must make sure the geometry is not included in the Speos Light Box of the Physical Camera. For more information, refer to Physical Camera Sensor - Specific Cases.
The Light Box must follow three important rules to be correctly used by the Physical Camera sensor:

  • The axis system of the Light Box must be defined so the optical axis of the lens system follows the Z axis.

    The axis system is defined during the export of the Light Box.

  • The origin of the axis system must be located with a small offset (around 10 times the Geometrical Distance Tolerance from the first face geometry).

  • The Light Box cannot include:
    • 3D textures
    • geometries with the optical properties: fluorescent materials, materials with volumic scattering properties, grating surface properties, doe/thin lens surface properties.

Lens geometries imported from OpticStudio are compatible.

Warning: A black-boxed Light Box is not compatible with the Physical Camera sensor.

Sequence File

The *.OPTSequence file corresponds to the file that determines the different paths available that rays can follow.

In the Physical Camera sensor, you have the possibility to add or not a Sequence file.

Important: The Physical Camera sensor is compatible with the Direct and Inverse simulations. However, the *.OPTSequence file depends on the simulation type. An *OPTSequence file generated with a Direct simulation can only be used as input in a Direct simulation. The same rule goes for the Inverse simulation.

Without Sequence File

It is possible not to add a sequence file. The Physical Camera sensor will only benefit from the Aiming Area. The optimized propagation engine makes sure that rays launched aim to this area. Once rays interfered with the aiming area the propagation is done following the Monte Carlo algorithm.

When no sequence file is used, you can only set the Layer separation type to Sequence in the Irradiance sensor.

Note: Not adding a sequence file to a Physical Camera sensor allows you to generate the future sequence file to be added to the Physical Camera sensor afterwards.

For more details on how to create this sequence file, refer to Creating an *.OPTSequene File for a Physical Camera Sensor.

With Sequence File

To get the most out of the Physical Camera sensor simulation performance, you may need to add a Sequence file previously generated. When a sequence file is added to a Physical Camera, rays aim to the Aiming Area, then propagate following the sequences saved into the sequence file (and not following the Monte Carlo algorithm).

Important: When inputting an *.OPTSequence file, the Physical Camera only keeps the sequences that enter the lens system from the first face of the system and exit the lens system from the last face of the system without exiting the lens system between the first and last faces.

For a better readability, in the Sequence Detection tool, the interactions before the lens system are not displayed.

The number of sequences followed is determined using the Number of sequences parameter.
  • You can create a sequence file for a one-source configuration. However, the drawback of generating a sequence file based on one source is that it highly depends on the light source and its position.

  • You can create a universal sequence file covering as many optical paths as possible. This way, you do not depend on a light source and its position, on the contrary, you can place light sources at different positions.

For more details on how to create this sequence file, refer to Creating an *.OPTSequene File for a Physical Camera Sensor.

Note: When an *.OPTSequence file is used in a Physical Camera, every generated simulation result filename (*.xmp, *.lpf, etc.) is suffixed with "_sequential".

Number of Sequences

Number of Sequences determines the number of sequences to play and provide into the *.xmp result file.

Number of Sequences is useful only if you add a sequence file as input of the Physical Camera.

Irradiance Sensor

The Irradiance sensor is a mandatory part of the Physical Camera.

The Irradiance sensor must follow three important rules to be correctly used by the Physical Camera sensor:
  • The Irradiance sensor must be positioned in the scene considering the lens system defined in the Light Box, which is usually placed in front of it.
  • The Integration type must be Planar.
  • Depending on whether you add a sequence file or not, the Layer type choice differs:
    • If you add no sequence file, you can only set the Layer separation type to Sequence in the Irradiance sensor.

    • If you add a sequence file, you can set any Layer separation type in the Irradiance sensor.

      Important: If you add a sequence file and you set the Irradiance sensor with the Layer separation type by Sequence, another *.OPTSequence file will be generated which will consider only the Number of sequences (X) set in the Physical Camera. That means, you will only have the X first sequences in the Sequence Detection tool during a Stray Light analysis.
Figure 1. Example: Physical Camera sensor with Sequence file + Irradiance Sensor with data separated by source