topic Re: Question about the camera coordinate system in Items with no label

Question about the camera coordinate system

ycao6 — Mon, 01 Oct 2018 05:43:39 GMT

I found some different descriptions about the camera coordinate system（point coordinate）

The pic below is the explanation of points coordinates which I consider as camera coordinate in this page

https://github.com/IntelRealSense/librealsense/wiki/Projection-in-RealSense-SDK-2.0# point-coordinates Projection in RealSense SDK 2.0 · IntelRealSense/librealsense Wiki · GitHub

But the explanation with red underline about point coordinates is different from what Intel RealSense Viewer shows （the pic below）

is the two coordinate system same ?

Thank you !!

Re: Question about the camera coordinate system

MartyG — Mon, 01 Oct 2018 07:16:54 GMT

In 3D mode, you can get a better idea of the camera's perspective by looking at the faint 3D projection lines that become visible if you pan the camera around. Ir projects a field of view that starts at a point at the camera's imager origin and widens outwards in all directions.

Because the lines are hard to see, I traced over them in my art software to illustrate them better.

The Z-depth arrow on the stream faces forward at whatever the camera is looking at from its perspective. So Z-distance will be positive because the detected Z increases as an object moves away from the camera, in the direction of the arrow.

Admittedly, I do not have an explanation for the direction of the Y arrow if Y-down = positive.

Re: Question about the camera coordinate system

ycao6 — Mon, 01 Oct 2018 07:38:17 GMT

So the coordinate system in the Viewer doesn't matter when I get my 3D coordinates of some objects . Is that right?

Re: Question about the camera coordinate system

MartyG — Mon, 01 Oct 2018 07:46:11 GMT

It would definitely be easier to rely on 3D XYZ coordinates output by a script. You can't get much meaningful information from the on-screen arrows in the Viewer in 3D mode, since - unlike 2D mode- there is not a coordinate readout.

Re: Question about the camera coordinate system

ycao6 — Mon, 01 Oct 2018 07:53:26 GMT

okay, Thank you very much !