I knew that kinect v2 camera can detect the skeleton joint position, but I need to know how can I determine the (x,y,z) position of a certain point in a room using kinect- v2 camera?
you can take a look at Vitruvius libraries as it has the thing u are looking for like joint position and measuring distance.
This gets the y coordinate of the left hand joint
Example of joint code: body.Joints[JointType.HandLeft].Position.Y
This gets the distance of the coordinates to the Kinect V2 sensor
Example of distance code: Length(_bodies[_token.BodyArrIndex].Joints[JointType.SpineBase].Position)
Vitruvius GitHub link: https://github.com/LightBuzz/Vitruvius
Vitruvius GitHub Gesture joints link: https://github.com/LightBuzz/Vitruvius/tree/master/Kinect%20v2/WPF/LightBuzz.Vitruvius/Gestures
Vitruvius website: https://vitruviuskinect.com/
Hope it helps!