Obtaining camera extrinsic parameters and the sensor size - ZED 2i camera

Hardware
1

Hi,
I’m interested in knowing if it’s possible to obtain the camera’s extrinsic parameters from the SDK without using the Python API. I’m not certain if these parameters are accessible via the Python API, but specifically, I need to acquire the rotation matrix and the translation vector. Additionally, I am looking to find out the physical size of the sensor (width and height in millimeters).

I have the following parameters already and would like to know if the parameters I’m seeking are included in this list:

[LEFT_CAM_2K]
fx=1914.85
fy=1915.48
cx=1089.38
cy=616.79
k1=-0.070943
k2=-0.0129377
p1=-0.00076779
p2=-0.000106157
k3=-0.0576469

[RIGHT_CAM_2K]
fx=1917.19
fy=1918.08
cx=1104.27
cy=625.885
k1=-0.0705111
k2=-0.0137826
p1=-0.00105397
p2=2.1827e-05
k3=-0.0601019

[LEFT_CAM_FHD]
fx=1914.85
fy=1915.48
cx=945.38
cy=535.79
k1=-0.070943
k2=-0.0129377
p1=-0.00076779
p2=-0.000106157
k3=-0.0576469

[RIGHT_CAM_FHD]
fx=1917.19
fy=1918.08
cx=960.27
cy=544.885
k1=-0.0705111
k2=-0.0137826
p1=-0.00105397
p2=2.1827e-05
k3=-0.0601019

[LEFT_CAM_HD]
fx=957.425
fy=957.74
cx=631.19
cy=356.395
k1=-0.070943
k2=-0.0129377
p1=-0.00076779
p2=-0.000106157
k3=-0.0576469

[RIGHT_CAM_HD]
fx=958.595
fy=959.04
cx=638.635
cy=360.9425
k1=-0.0705111
k2=-0.0137826
p1=-0.00105397
p2=2.1827e-05
k3=-0.0601019

[LEFT_CAM_VGA]
fx=478.7125
fy=478.87
cx=331.095
cy=185.6975
k1=-0.070943
k2=-0.0129377
p1=-0.00076779
p2=-0.000106157
k3=-0.0576469

[RIGHT_CAM_VGA]
fx=479.2975
fy=479.52
cx=334.8175
cy=187.97125
k1=-0.0705111
k2=-0.0137826
p1=-0.00105397
p2=2.1827e-05
k3=-0.0601019

[LEFT_DISTO]
k1=1.97707
k2=14.5644
k3=-3.41367
k4=2.09771
k5=14.3992
k6=-1.48083
p1=-0.000789978
p2=-6.65559e-05

[RIGHT_DISTO]
k1=-2.86888
k2=26.8395
k3=-11.3017
k4=-2.7715
k5=26.4735
k6=-9.02896
p1=-0.00107144
p2=-4.86188e-06

[STEREO]
Baseline=119.958
TY=-0.267137
TZ=0.532289
CV_2K=0.0055762
CV_FHD=0.0055762
CV_HD=0.0055762
CV_VGA=0.0055762
RX_2K=0.0033253
RX_FHD=0.0033253
RX_HD=0.0033253
RX_VGA=0.0033253
RZ_2K=0.00194325
RZ_FHD=0.00194325
RZ_HD=0.00194325
RZ_VGA=0.00194325

[MISC]
Sensor_ID=0

Could you please let me know if the extrinsic parameters I’m looking for are available in the data I’ve provided?

Thank you for your assistance.

2

The extrinsic parameters are reported here:

[STEREO]
Baseline=119.958
TY=-0.267137
TZ=0.532289
CV_2K=0.0055762
CV_FHD=0.0055762
CV_HD=0.0055762
CV_VGA=0.0055762
RX_2K=0.0033253
RX_FHD=0.0033253
RX_HD=0.0033253
RX_VGA=0.0033253
RZ_2K=0.00194325
RZ_FHD=0.00194325
RZ_HD=0.00194325
RZ_VGA=0.00194325

Here you can find the explanation of the fields:

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3

Thanks. I am trying to get the parameters from camera using below code, but this results in an AttributeError , indicating that the CalibrationParameters object does not have a T attribute. Could you please advise how can I solve it?

import pyzed.sl as sl

zed = sl.Camera()
init_params = sl.InitParameters()
if zed.open(init_params) != sl.ERROR_CODE.SUCCESS:
exit(1)

camera_info = zed.get_camera_information()
calibration_params = camera_info.camera_configuration.calibration_parameters

print(f"Tx: {calibration_params.T.x}")

4

Hi @code_lover,

The left to right camera transform is accessible with the stereo_transform attribute of the CalibrationParameters class.

stereo_transform = camera_info.camera_configuration.calibration_parameters.stereo_transform
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