AutoTRASSIR (ANPR) recommendations

Recommendations on characteristics for choosing the cameras:

• Regarding the resolution of the cameras - AutoTRASSIR module does not depend much on the resolution. And since higher resolution requires more network, HDD and CPU/GPU resources - it is not recommended to use resolution higher resolution where it is not required. Resolution of 2 MP is a good balanced choices for the most of the cases.
  Required PPM value in recognition zone is 250.
• Matrix size from 1/2.8" (minimal required) to 1/1.8" depending on the lighting conditions.
• Aperture from F1.6 (minimal required) to F1.2 depending on the lighting conditions.
• Possibility of shutter speed control and to make it fixed. Moving objects have to be clearly visible. Depending on installation angles and vehicle speed there is a requirement for the shutter speed - see the picture below*
• Varifocal lens at least x4 optical zoom. The focal length should be adjusted so that the car license plate in the video occupies about 120-140 pixels in width horizontally.
• The more light sensitive will be the matrix - the better. FTC cameras are good option.
• HLC support.
• Onvif-compliance (at least S).

Recommendations on camera settings:

• Camera bitrate has to be sufficient for required resolution, fps an motion intensity. The camera picture has to be stable, without noise and glitches.
• Codec has to be H.264.
• Disable autofocus on camera.
• Disable OSD text on camera if possible.
• Disable camera software picture enhancements. HLC is appropriate, if needed

Factors other than camera characteristics and settings, affecting the AutoTRASSIR performance:

• The lighting in the scene of detection should be sufficient and equal. At the night time, there should be no overexposure of the objects.
• The positioning of the camera. Ideal vertical and horizontal angles are 15 degrees, permissible value is 30 degrees.

*Required shutter speed depending on the vehicle speed and installation angle:

Examples of good angles and image quality: