Re-add the camera/depth map intrinsics

[robman]

Heya,

I think these should at least be 'optional' e.g. if available - especially on mobile platforms (which is really just Android right now).

In the Android Camera API these values are available - see https://developer.android.com/reference/android/hardware/camera2/CameraCharacteristics.html

Specifically this https://developer.android.com/reference/android/hardware/camera2/CameraCharacteristics.html#LENS_INTRINSIC_CALIBRATION

(NOTE: Optional - The value for this key may be null on some devices.)

Also somewhat related:

• DEPTH_DEPTH_IS_EXCLUSIVE
• LENS_DISTORTION
• LENS_FOCAL_LENGTH
• LOGICAL_MULTI_CAMERA_SENSOR_SYNC_TYPE
• LENS_POSE_REFERENCE
• LENS_FACING

Plus:

• https://developer.android.com/reference/android/hardware/camera2/CameraMetadata.html#REQUEST_AVAILABLE_CAPABILITIES_DEPTH_OUTPUT

Also see this relevant document (especially the camera intrinsics, depth map and pose sections) https://developer.android.com/training/camera2/Dynamic-depth-v1.0.pdf

@astojilj I think it was a bit draconian removing them all in #168 to force webcam style limitations onto mobile platforms.

Thoughts @huningxin @anssiko ?

[anssiko]

@astojilj is no longer working on this, looping in @riju instead.

[robman]

Thanks @anssiko - I pinged him on twitter too 8)