ZED API and ZED SDK calibration parameters discrepancy


I’m trying to automatically retrieve the calibration parameters of a ZED camera using .svo files with the next script:

        self.input_type = sl.InputType()
        self.init = sl.InitParameters(input_t=self.input_type, svo_real_time_mode=False)    
        self.init.camera_resolution = sl.RESOLUTION.HD1080
        self.init.depth_mode = sl.DEPTH_MODE.NEURAL
        self.cam = sl.Camera()
        self.status = self.cam.open(self.init)
        if self.status != sl.ERROR_CODE.SUCCESS:

        calibration_params = self.cam.get_camera_information().camera_configuration.calibration_parameters_raw
        focal_left_x = calibration_params.left_cam.fx
        focal_left_y = calibration_params.left_cam.fy
        principal_left_x = calibration_params.left_cam.cx
        principal_left_y = calibration_params.left_cam.cy

When executing it wih a .svo file I get the next results:
focal_left_x: 739.197998046875
focal_left_y: 739.073974609375
principal_left_x: 972.2130126953125
principal_left_y: 527.6489868164062
Upon opening the same .svo file with the ZED_Explorer from the SDK I can see the next window:

As you can see the cy parameter is different. Is this normal?

The purpose of doing this is to be able to grab an (x, y) pixel coordenate on a frame, get the current (Xo, Yo, Zo) coordenate in the point cloud data and compare it to the (X1, Y1 , Z1) in the same pixel if the depth was different.
As I understand it this is possible by using the intrinsic camera parameters as follows:

K = np.array([[fx, 0, cx],
              [0, fy, cy],
              [0, 0, 1]])

# Pixel coordinates and depth example values
x = 340
y = 240
Z = 5.0

# World coordinates (X, Y, Z) calculation
pixel_coords = np.array([x, y, 1])
inv_K = np.linalg.inv(K)
world_coords = Z * np.dot(inv_K, pixel_coords)

Any comments would be apreciated. Thank you in advanced.

indeed it is not expected.
ZED Explorer should report the same parameters as the ones from calibration_parameters_raw.
Can you share your camera serial number? I will be easier for us to check what’s going on.

1 Like

The camera is a ZED X, the serial number is 48284538.

which version of the ZED SDK do you use?
in your case, the values reported by the SDK are correct, not the one from ZED Explorer.
In the current 4.0.8 version ZED Explorer displays the correct ones

The SDK version is 4.0.7. But I also opened the .svo file from a 4.0.8 ZED Explorer in a ZED Box Orin, from which I recorded the video and the cy value remains the same (587.6490)