Software User Manual - Argos 3D-P320
Last change: 2 February 2016
Version 0.14
© Bluetechnix 2016
Page 41 | 70
For each pre-defined modulation frequency, there is an absolute offset in millimeters that all distance values
are corrected with. The absolute offsets are stored in registers
DistOffset0
(for 5 MHz modulation frequency)
to
DistOffset6
(for 30 MHz). Offsets can be modified by direct register writes.
Distance Offset correction is enabled or disabled in register
ImgProcConfig
.
The camera has also a built-in offset calibration function, which is described in the following procedure. You
let the camera know the real distance and the camera will calculate the correct absolute offset. It uses a
square of 4x4 pixels in the center of the distance image.
Procedure
Offset Calibration
1.
Place your Argos co-planar in front of a uniform white target.
2.
Avoid extreme environmental light conditions or avoid light completely.
3.
Set the desired modulation frequency using register
ModulationFrequency
.
4.
Check the amplitude in the center of the image and increase/decrease the
IntegrationTime
until the amplitude is about 3000-5000 in the center.
5.
Measure the real distance in millimeters from the camera to the white target. Write
this value into register
RealWorldXCoordinate
.
6.
Write decimal value 19 into register
CalibrationCommand
and wait until the
CalibStatus
register, Bits 0..7, read decimal value 161 (= finished).
The appropriate
DistOffsetX
register is updated.
7.
If you want to keep the setting, don’t forget to save registers to flash (Chapter
4.15.3).
4.12
ToF Automatic Exposure Control (AEC)
The Argos 3D-P320 provides an automatic exposure control feature which controls the integration time
according to the currently observed scene. The AEC is disabled by default and must be enabled in the
register
Mode1
.
The AEC is controlled through dedicated registers, which are listed in chapter 5.5.
The AEC algorithm also supports weighing. One may assign specific weights to each of 25 areas into which
the sensor area is divided. These weights are inputs to calculate the current amplitude. Please see Figure
4-9: AEC weighing areas for an illustration. Each area’s weight is a Uint8 value and can range from 0% (0x0)
to 100% (0xf).
