Understanding Camera Sensor Parameters

General

Mode

The Geometric mode is a simplified version of the Camera Sensor definition parameters. The rendering properties are used by default during the mesh generation.

The Geometric camera sensor can be used only in inverse simulations without sources and other sensors.

When you enable the Geometric mode, the parameters relative to spectrum or spectral data are disabled.
The Photometric / Colorimetric mode allows you to set every Camera Sensor parameters, including the photometric definition parameters.

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".

Layer

Note: The Layer is available only in Photometric / Colorimetric Mode.

Layers allows you to store all photometric results in the same XMP layer or not:

None includes the simulation's results in one layer.
Data Separated By Source includes one layer per active source in the result.

Optics

According to the *.OPTDistortion file model used as input of the Camera, the Optics section provides you with different parameters.


Parameter	Description	V1	V2 & 2.1	Binary
Focal length (mm)	Distance between the center of the optical system and the focus. For more information, click here.
Imager distance (mm)	The imager is located at the focal point. The Imager distance has no impact on the result.
F-number	F-number represent the aperture of the front lens. F number has no impact on the result. For more information, click here.
Transmittance	The Transmittance file is available only in Photometric / Colorimetric Mode. Amount of light of the source that passes through the lens and reaches the sensor. The transmittance is expressed in a .spectrum file. For more information, click here.
Horizontal field of view (deg)	Horizontal field of view calculated using the focal length, distortion file, width and height of the sensor.
Vertical field of view (deg)	Vertical field of view calculated using the focal length, distortion file, width and height of the sensor.
Distortion	Optical aberration that deforms and bend straight lines. The distortion is expressed in a .OPTDistortion file. For more information on the .OPTDistortion file, see Camera Models. For more information, click here.

Sensor


Parameter	Description
Horizontal pixels	Defines the horizontal pixels number corresponding to the camera resolution.
Vertical pixels	Defines the vertical pixels number corresponding to the camera resolution.
Width	Defines the sensor's width.
Height	Defines the sensor's height.
Color mode	The Color mode is available only in Photometric / Colorimetric Mode. Color: simulation results are available in color according to the White Balance mode. Monochrome: simulation results are available in grey scale.
White balance mode	Note: The White balance mode is useful in case of a visible spectrum. The White balance mode will not work in the Infrared and the UV spectrum. The White balance mode is available only in Photometric / Colorimetric Mode. None: The spectral transmittance of the optical system and the spectral sensitivity for each channel are applied to the detected spectral image before the conversion in a three channel results. This method is referred to as the basic conversion. Grey world: The grey world assumption states that the content of the image is grey on average. This method converts spectral results in a three channel results with the basic conversion. Then it computes and applies coefficients to the red, green and blue images to make sure their averages are equal. User white balance: In addition to the basic treatment, it allows you to apply your own coefficients to the red, green, blue images. Display primaries: Spectral results are converted in a three channels result. Then a post-treatment is realized to take the distortion induced by the display devices into account. With this method, displayed results are similar to what the camera really gets.
Gamma correction	The Gamma correction is available only in Photometric / Colorimetric Mode. Compensation of the curve before the display on the screen. For more information, see Monitor.
PNG bits	The PNG bits is available only in Photometric / Colorimetric Mode. Choose between 8, 10, 12 and 16-bit.

Sensitivity

The Sensor sensitivity is available only in Photometric / Colorimetric Mode.

Sensor sensitivity allows you define the spectral sensitivity of the camera sensor according to the color mode selected.

Wavelength

The Wavelength is available only in Photometric / Colorimetric Mode.

Wavelength allows you to define the spectral range in which the inverse simulation propagates rays from the sensor.

Start (nm) defines the minimum wavelength.
End (nm) defines the maximum wavelength.
Sampling defines the number of wavelength to be taken into account between the minimum and minimum wavelengths set.

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".

Visualization

Visualization allows you to define the elements (Camera field, Object field, Aperture) of the camera to display in the 3D view.

Visualization Radius changes the radius of the Object field of the camera.

Note: Visualization Radius has no impact on the result.