Recording through a window

[KieDani]

Hello,
I want to collect a scientific dataset (e.g. with the ZED 2i). Therefore, I want to record a video of a scene through a window and obtain the two RGB images as well as the depth map of the scene. Is it possible to obtain the depth map if the scene is filmed through window glass/plastic?

[Myzhar]

Hi @KieDani
Welcome to the Stereolabs community.

As far as the window does not introduce image distortions you can use it.
Be sure to place the camera in strict contact with it and verify with ZED Depth Viewer that the right and left images are not distorted and the depth map is reporting correct depth values.

If the window introduces distortions, then you must run a manual calibration by using the ZED Calibration tool.

[KieDani]

Thank you for your response. That is great news.
Just to be sure, this means the ZED cameras do not use infrared technology (since a window could disturb those signals)?

[Myzhar]

No, the ZED devices are passive stereo cameras, no IR light is used

[mnow97]

Hi @Myzhar I have some follow up questions on this same topic:

1. I am planning to use flat borosilicate/tempered glass to protect the camera lens, which will be placed about 1mm in front of my ZED2 camera. Do you see any issues that may happen or it needing recalibration? The glass should be less than 3mm thick.
2. How do I verify quantitatively whether the camera needs recalibration?
   a.Do you have a tool to do the same, accounting for measurement variances in the camera?
   b. Is the only way to make real world measurements and compare with the depth map before and after adding the glass?
   c. I have an alternate plan, to recalibrate the zed2 manually with and without the glass and compare the calibration parameters, to see if it has any effect. Is this a valid way of going about this? If there is no effect then I will just use the factory settings.

[Myzhar]

@mnow97

I am planning to use flat borosilicate/tempered glass to protect the camera lens, which will be placed about 1mm in front of my ZED2 camera. Do you see any issues that may happen or it needing recalibration? The glass should be less than 3mm thick.

You must verify that the glass does not introduce distortions, otherwise, a manual calibration is required.

@mnow97

How do I verify quantitatively whether the camera needs recalibration?
a.Do you have a tool to do the same, accounting for measurement variances in the camera?
b. Is the only way to make real world measurements and compare with the depth map before and after adding the glass?
c. I have an alternate plan, to recalibrate the zed2 manually with and without the glass and compare the calibration parameters, to see if it has any effect. Is this a valid way of going about this? If there is no effect then I will just use the factory settings.

You can use a chessboard normally used for calibration, take a few pictures of it and verify that all the points of the chessboard are correctly aligned.