Update RGBD camera config files

[PeterBowman]

PR robotology/yarp#1960 added a new required physFocalLength parameter to groups RGB_INTRINSIC_PARAMETERS and DEPTH_INTRINSIC_PARAMETERS. We should update share/sensors/conf/asus-xtion.ini. Featured in YARP 3.2.0.

[PeterBowman]

The EXTRINSIC_PARAMETERS group is optional, hence could be removed if not used. Note to self: reference current ASUS Xtion values (link) in the .ini file.

[PeterBowman]

Currently missing specs (ASUS Xtion Pro Live, ref):

• FOV: 58° H, 45° V, 70° D (Horizontal, Vertical, Diagonal) -> depth_Fov (also rgb_Fov?), only horizontal and vertical
• Distance: Between 0.8m and 3.5m -> clipPlanes

[PeterBowman]

Sensor transform and depth accuracy estimations for Kinect 1, Kinect 2 and ASUS Xtion Pro Live: Filippo Basso, Emanuele Menegatti, and Alberto Pretto, "Robust Intrinsic and Extrinsic Calibration of RGB-D Cameras", 2018 (arxiv).

[PeterBowman]

Kinect 1 & Kinect 2 resolution, FOV and depth distance (thanks, @jgagom; https://github.com/roboticslab-uc3m/sign-language-papers/issues/19#issuecomment-479110680):

[PeterBowman]

Kinect intrinsics (includes distortion params) and extrinsic transform (ref):

# Calibration file 
# ---------------------------------------------------------
# Left camera (IR/Depth in Kinect) calibration parameters
[CAMERA_PARAMS_LEFT]
resolution = [640 488]
cx         = 314.649173
cy         = 240.160459
fx         = 572.882768
fy         = 542.739980
dist       = [-4.747169e-03 -4.357976e-03 0.000000e+00 0.000000e+00 0.000000e+00]    // The order is: [K1 K2 T1 T2 K3]
 
# Right camera (RGB in Kinect) calibration parameters
[CAMERA_PARAMS_RIGHT]
resolution = [640 480]
cx         = 322.515987
cy         = 259.055966
fx         = 521.179233
fy         = 493.033034
dist       = [5.858325e-02 3.856792e-02 0.000000e+00 0.000000e+00 0.000000e+00]    // The order is: [K1 K2 T1 T2 K3]
 
# Relative pose of the right camera wrt to the left camera:
# This assumes that both camera frames are such that +Z points
# forwards, and +X and +Y to the right and downwards.
[CAMERA_PARAMS_LEFT2RIGHT_POSE]
pose_quaternion      = [0.025575 -0.000609 -0.001462 0.999987 0.002038 0.004335 -0.001693]
# ---------------------------------------------------------

I guess this is the Kinect 1 sensor, but given resolution values look suspicious.

[PeterBowman]

Even moar params for both Kinects at Diana Pagliari and Livio Pinto, "Calibration of Kinect for Xbox One and Comparison between the Two Generations of Microsoft Sensors", 2015 (full text): resolution, distance, FOV, intrinsics (given in millimeters and pixels)...

[PeterBowman]

Commit d8af84b unbreaks the ASUS Xtion for recent YARP releases.

[PeterBowman]

Kinect2 depth parameters as used in OpenCV's rgbd module samples (link):

namespace Kinect2Params
{
static const Size frameSize = Size(512, 424);
// approximate values, no guarantee to be correct
static const float focal = 366.1f;
static const float cx    = 258.2f;
static const float cy    = 204.f;
static const float k1    = 0.12f;
static const float k2    = -0.34f;
static const float k3    = 0.12f;
};  // namespace Kinect2Params