I've got an Oak-D Pro W POE. I am attempting to flash our own calibration to it with the depthai library and a calibration json file, and I've got a few questions. Attached is a sample calibration json file. 1. Which socket corresponds to which camera? at the bottom, it specifies leftCameraSocket: 1 and rightCameraSocket: 2. However, in the cameraData section, looking at the toCameraSocket, it appears that the RGB camera is -1, the LEFT camera is 2, and the RIGHT is 1. Is this correct? Are these referring to something else? 2. What is the origin frame of the extrinsics (which camera frame)? 3. Are all 3 cameras in the same frame? If so, how is it that the specTranslation says the left camera is a -3.75 in "x" and the right camera is at +7.5 in "x"? Wouldn't that imply that they're 11.25 cm apart? Also, is there documentation on these calibration jsons that I can refer to? I've seen the website about flashing/loading/reading calibration, but wondering if there's something I'm missing. Thanks!

Following this up, I've run a few more tests and it appears that: * socket 0 is RGB, * socket 1 is LEFT * socket 2 is RIGHT Is this correct? Thank you.

A few questions about flashing a calibration

henry0987

I've got an Oak-D Pro W POE. I am attempting to flash our own calibration to it with the depthai library and a calibration json file, and I've got a few questions. Attached is a sample calibration json file.

Which socket corresponds to which camera? at the bottom, it specifies leftCameraSocket: 1 and rightCameraSocket: 2. However, in the cameraData section, looking at the toCameraSocket, it appears that the RGB camera is -1, the LEFT camera is 2, and the RIGHT is 1. Is this correct? Are these referring to something else?
What is the origin frame of the extrinsics (which camera frame)?
Are all 3 cameras in the same frame? If so, how is it that the specTranslation says the left camera is a -3.75 in "x" and the right camera is at +7.5 in "x"? Wouldn't that imply that they're 11.25 cm apart?

Also, is there documentation on these calibration jsons that I can refer to? I've seen the website about flashing/loading/reading calibration, but wondering if there's something I'm missing.

Thanks!

lovro

Hi, yes you got it right:

Socket 0 is RGB (middle one)
Socket 1 is right stereo
Socket 2 is left stereo

The toCameraSocket tells which camera the position is relative to. Usually they are relative to socket 0 (RGB), which is the center and used as origin.

So for example, if you see:

"specTranslation": { "x": -7.5, ... },

"toCameraSocket": 2

that means this camera is 7.5 cm to the left of camera 2, not from the center directly. You have to check which socket it’s using as reference.

In your calibration:

Left cam (socket 2) is at +3.75 cm from RGB
Right cam (socket 1) is at –7.5 cm from left → so it ends up at –3.75 cm from RGB

This gives stereo baseline of 7.5 cm, and RGB camera is in the middle, between the two.

Hope it helps !

henry0987

Hi @lovro thanks for the reply. So that makes sense, but what about the bottom of the calibration json (in the stereoRectificationData section) where it says leftCameraSocket: 1 and rightCameraSocket: 2? I thought left was 2, and right was 1?

henry0987

Following this up, I've run a few more tests and it appears that:

socket 0 is RGB,
socket 1 is LEFT
socket 2 is RIGHT

Is this correct? Thank you.

lovro

Hi @henry0987
you're absolutely right, and apologies for the earlier mistake.

Socket 0 is indeed rgb, socket 1 is left, and socket 2 is right, as confirmed by both the cameraData and the stereoRectificationData in calibration JSON.

Thanks for pointing it out and double-checking!