# Unit of calculated world coordinates

Hello, I have a basic question.

I have a calibrated stereo camera. I detected features, matched keypoints and calculated my translation and rotation vector.

What is the unit of my calculated world coordinates? Does 1.0 equal my square size of the calibration?

depends on the calibration.

if you said your squares are â€ś1â€ť, then thatâ€™s the unit. if you said your squares are 20 (millimeters), or 0.020 (meters), or something, itâ€™ll work with that.

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Thanks for your reply.
The suqare size I used was 5 millimeters. Is there a best practive for the unit?
For example it is best practive to use meter and thereforeto you have to write 5mm as 0.005.

meters are a good idea. some might use inches. some might use nanometers or light years. depends on the purpose.

an even better idea is to measure the true size of your squares. measure across the whole sheet and divide by number of steps for better accuracy. separately measure vertical and horizontal results. printers turn squares into rectangles.

the calibration routines donâ€™t care how you get the numbers or what they mean, but they care that the â€śmodelâ€ť you provide doesnâ€™t contradict reality too much.