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Modeling Built-in IR Illuminator

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Modeling Built-in IR Illuminator

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Modeling Built-in IR Illuminator

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Cameras with built-in infrared illumination are known to be able to see in complete darkness in black and white at a limited distance.

With an increase of the distance from the camera to the target, the image quality of the target decreases and from a certain distance the image quality is considered unacceptable. The maximum distance beyond which the quality is already too bad is sometimes given in the specifications of cameras.

The problem is that there are no generally accepted criteria for the minimum acceptable image quality, and therefore at the maximum distance from the specifications of different cameras, images of different quality can be obtained. As well as other ambiguous specification parameters, the maximum IR illumination distance carries a large marketing load.

 

 

VideoCAD provides rigorous tools for physically accurate modeling the IR illumination and camera sensitivity, but the camera specifications do not contain parameters necessary for modeling. Sometimes there is only the maximum distance of the IR illumination - a parameter that has no physical meaning without specifying the image quality of the target at the maximum distance.

 

In such conditions, several ways of practical use of IR illumination modeling tools are possible:

 

1. Using only the Maximum distance from the camera specification.

 

2. Using the Maximum Distance with testing the image quality.

 

3. Complete modeling by parameters.

 

Using only the Maximum distance from the camera specification.

 

 

In this way, you will get a project with marked IR illumination zones, but the image quality at the Maximum distance will remain known only to the camera manufacturer.

 

1. Activate camera for modeling IR Illumination. The camera must be day/night or black/white.

2. Open the Built-in IR Illuminator panel by clicking on the Built-in IR Illuminator button on the Toolbar.

 

3. Set the IR illumination parameters:

 

ON - to enable simulation of IR illumination;

 

Wavelength, Radiation power (W), Angle of radiation - values ​​will not be used;

 

= max. view angle - mark that the angle of radiation of the IR illumination is set automatically according to the view angles of the camera;

 

Concentration - 0.7 (average value by default);

 

Max. distance (m) - the maximum distance known to us from the camera specification;

 

Calculate from - uncheck to disable automatic calculation of the maximum distance;

 

Show on layout - mark.

 

 

 

 

 

As a result, on the layout, we will obtain the IR illumination zone of the active camera calculated from the Maximum distance.

 

The horizontal projection of the IR illumination zone is calculated according to the same rule as the horizontal projection of the view area:

 

A point on a horizontal projection is considered sufficiently illuminated if the vertical segment formed by this point in the range of heights from the view area lower bound to the the view area upper bound is fully illuminated.

 

Instead of the projection, it is possible to display separately the sections of the IR illumination zone with the lower and upper bounds of the view area, if you select on the Toolbar View area projection bounds> 2 levels. Or Shadow > 2 levels.

 

In the vertical projection of the Graphics window, the IR illumination zone of the active camera is displayed in the graphical editing state of the active camera.

 

The line type for displaying the boundaries of the IR illumination zone can be changed in the Options box.

 

 

 

Using the Maximum Distance with testing the image quality

 

 

To follow this path, you must have test images from the camera of this model with a person at several distances from the camera, up to the maximum distance.

 

It is necessary to ensure that the person is the brightest object in the frame and there are no extraneous light sources.

 

Competent testing of sensitivity and IR illumination requires knowledge that is beyond the scope of this example.

 

1. Activate camera for modeling IR Illumination. Assign parameters of the tested camera model. The camera must be day/night or black/white.

2. Open the 3D Video, Image processing must be not disabled.

3, Place a 3D model of a person at a distance specified when getting the test image. Aim the camera exactly at the 3D Model, the model should be at the center of the screen.

4. Right click on the 3D Video window to display the Image parameters panel.

5. Go to the View  tab and uncheck the Background, Grid, Ground surface checkboxes

6. Go to the Scene, then on the Night tab.  Select 0 in the Background illumination box. The Model Illumination and Illuminators checkboxes must be checked.

7. Go to the PiP, Mark ON. Place the yellow box on the test 3D Model by clicking the middle mouse button on the 3D Video window. The 3D Model should be the brightest subject in the frame.

8. Open the Built-in IR illuminator panel by clicking on the Built-in IR illuminator button   on the Toolbar.

 

9. Set the IR illumination parameters:

 

ON - to enable simulation of IR illumination;

 

Wavelength, Radiation power (W), Angle of radiation - values ​​will not be used;

 

= max. view angle - mark that the angle of radiation of the IR illumination is set automatically according to the view angles of the camera;

 

Concentration - 0.7 (average value by default);

 

Max. distance (m) - the distance known to us, given when receiving the test image;

 

Calculate from - uncheck to disable automatic calculation of the maximum distance;

 

Show on layout - mark.

 

By selecting the parameter Radiation power (W) achieve the image quality of the 3D model in the 3D Video window, in the green PIP frame, close to the image quality of the real person on the test image. Change the camera sensitivity settings if necessary. .

 

Thus, you can get the approximate parameters of the built-in IR illumination model, at which the image quality is close to the test result.

Using these parameters, you can simulate the image quality of models located at any distance, evaluate effects of changes in power, angle of radiation, exposure time, etc.

 

Complete modeling by parameters

 

 

For a full-fledged simulation, you need to fill in the parameters on the Built-in IR illuminator panel:

 

Wavelength (nm)
Radiation power (W)
Radiation angle (deg.)
Concentration

 

To calculate the maximum distance of IR illumination from the parameters of the IR illuminator and camera sensitivity, check the Calculate from checkbox and select in the Signal/noise ratio box the minimum allowable signal-to-noise ratio of the object image at the border of the IR illumination zone.

 

For the calculation, you must also set the camera sensitivity parameters:

 

Min/ illumination(lx)

AT:

Apperture
Signal/Noise ratio (dB)
IRE
exposure (ms)

 

And aperture of the lens:

 

Current aperture (F- number).

 

Currently, many of the required parameters are missing in the camera specifications, so full-fledged IR illumination modeling is possible only after testing the cameras.

 

See also: Built-in IR illuminator