Is it OK to mount the Azure Kinect cameras upsidedown?

Question

We have an application where we operate the Azure kinect cameras in WFOV depth mode. As shown in

https://learn.microsoft.com/en-gb/azure/Kinect-dk/hardware-specification

The active RGB video region is a rectangle positioned in the upper semicircle of the depth region. We are actually more interested in the lower semicircle of the depth region so is it acceptable to mount the cameras upsidedown? Obviously we will have to perform our own custom processing to re-orient the images.

Just wondering if there might be problems with the passive air cooling when operating like this (or with the cameras on their side)?

Best regards,
David Robb

Answer 1

@DavidRobb-6688 There is no problem with mounting the Azure Kinect camera upside down. You can also use the accelerometers in the IMU to understand the device orientation.

Answer 2

Hi Quentin,

That is good news. Thanks.

This also got us thinking how the WFOV circular pattern maps onto the 512x512 array of depth points. Looking at the generated calibration table in the example code, it appears that the circle fits inside the square with the non-overlapping pixels marked as invalid. It also appears that the distribution is linear in X and Y.

However, as shown in the specifications, the cone generated from the WFOV mode camera extends further down than up. So even though the 512x512 pixels are linearly distributed across the circle, does this make the pixels in the upper half intrinsically more accurate and less noisy than the lower half?

Answer 3

There are some additional Fresnel losses caused by the front window due to the higher angles of incidence at the bottom of the WFOV. We do not have precise quantification of the degree of loss. The temporal standard deviation should be lowest in the center of the FOV, even though it is slightly tilted downwards. We definitely expect there to be some top/bottom asymmetry due to the Fresnel losses and some left-right effects if the target is very close and there are issues due to the illumination-imaging baseline. The lens itself is tilted downwards slightly due to the entire module being tilted – the lens itself it centered on the imaging array for depth in the X-Y dimension. There are some additional radial effects due to lens RI and the illumination diffuser which is designed to partly compensate for the lens RI. Certainly for WFOV we expect some significant performance drop-off towards the very edges.