Saving/Loading intrinsics to/from a file

[jimwormold]

---

Required Info
Camera Model	{ D400 }
Firmware Version	(5.10.03)
Operating System & Version	Win 7
Kernel Version (Linux Only)
Platform	PC
SDK Version	{ 2.20 }
Language	python
Segment	{others }

Issue Description

I would like to be able to save off the intrinsics and reload them as required for running unit tests against individual frames rather than having to open a bagfile each time (storing multiple bag frames is not an option due to size).

This is related to this issue, but I can't find an issue raised on github...

https://forums.intel.com/s/question/0D50P0000490LwGSAU/how-to-save-load-intrinsics-to-from-file-python?language=en_US

UPDATE:

While I can't save/serialize them, I notice that I can now create an rs2.intrinsics object and set the parameters based upon those from the camera (I think these used to be read-only), so this is an accepable work around:

 def make_intrinsics(self):
        '''
        Avoid having to read a bagfile to get the camera intrinsics
        '''
        # Copied from a bagfile's intrinsics
        intrinsics = rs.intrinsics()
        intrinsics.coeffs = [0,0,0,0,0]
        intrinsics.fx = 639.2603759765625
        intrinsics.fy = 639.2603759765625
        intrinsics.height = 720
        intrinsics.ppx = 640.6775512695312
        intrinsics.ppy = 355.451171875
        intrinsics.width=1280
        return intrinsics