Reprojection of 3D points of Superquadrics Curvature caught by Kinect IR-depth sensor

to CCD of RGB camera

Mariolino De Cecco, Nicolo Biasi, Ilya Afanasyev

Facoltà di Ingegneria

Trento, 2012

21/11/2011 1/20

Content

2/20

1. Kinect installation.2. Kinect calibration.3. Kinect outputs.4. MATLAB Preprocessing Kinect data.5. MATLAB Inputs.6. SQ Curvature Software.7. Tests.8. Results.9. Links.

21/11/2011

Kinect installation

3/20

1. OpenNI backend:1. Nicolas Burrus software [1]: Kinect RGBDemo v0.6.1. -> supports OpenNI/Nite

backends [2] and has the experimental infrared support with OpenNI (still buggy) -> I tried to check this work for OpenNI backend under Windows 64bit.

2. Install Sensor Kinect drivers under Windows 32 bit [3] and OpenNI/Nite modules (Win32) [2] according to the instruction [4] and verified that they work properly.

3. Use RGB-D Capture [1] to grab Kinect RGB and IR images with intensity.raw and depth.raw files. -> the software doesn’t grab IR images!! -> only RGB image, intensity.raw, depth.raw and calibration file (calibration.yml without distortion parameters)!!

4. “calibrate-openni-intrinsics --pattern-size 0.0405 grab1 calibration.yml” -> gives “openni_calibration.yml” with Intrinsic matrix and distortion coefficients for Kinect RGB camera !!

5. “calibrate-openni-depth.exe --pattern-size 0.0405 grab1” gives partly processed figures with a message about errors.

21/11/2011

1st attempt

The comparison of Kinect calibration results for - Libfreenect backend (under OS Linux / Ubuntu 10.10 - 32 bit) - OpenNI backend (under OS Windows 32bit)

- 23/11/2011

The same figures of Intrinsic Matrixes for Kinect RGB and

Depth Cameras

Libfreenect backend OpenNI backend

The Depth Camera Calibration for OpenNI backend is

NOT available!!!

The comparison of Kinect calibration results for - Libfreenect backend (under OS Linux / Ubuntu 10.10 - 32 bit) - OpenNI backend (under OS Windows 32bit)

- 23/11/2011

There is NO extrinsic mapping between Kinect Depth and RGB

cameras for OpenNI backend

Libfreenect backend OpenNI backend

The reprojection of 3D points from Kinect Depth Camera to

RGB image for OpenNI is NOT possible!!

Kinect installation

6/20

1. Libfreenect backend (Windows):1. Nicolas Burrus software [1]: Kinect RGBDemo v0.6.1. -> supports

Libfreenect backend [2] and has RGB and infrared support -> I tried to check the work under Windows 64bit.

2. Install Xbox NUI Motor drivers under Windows 32 bit [3] and OpenNI/Nite modules (Win32) [2] according to the instruction [4] and verified that they work properly.

3. Use RGB-D Capture [1] to grab Kinect RGB and IR images with intensity.raw and depth.raw files. -> the software doesn’t grab IR images!! -> only RGB image, intensity.raw, depth.raw and calibration file (calibration.yml without distortion paraeters)!!

4. “calibrate-openni-intrinsics --pattern-size 0.025 grab1 calibration.yml” -> gives “openni_calibration.yml” with Intrinsic matrix and distortion coefficients for Kinect RGB camera !!

5. “calibrate-openni-depth.exe --pattern-size 0.025 grab1” gives partly processed figures with a message about errors.

21/11/2011

2nd attempt

Kinect installation

7/20

1. OpenNI backend:1. Nicolas Burrus software [1]: Kinect RGBDemo v0.6.1. -> supports OpenNI/Nite

backends [2] and has the experimental infrared support with OpenNI (still buggy) -> I tried to check this work for OpenNI backend under Windows 64bit.

2. Install Sensor Kinect drivers under Windows 32 bit [3] and OpenNI/Nite modules (Win32) [2] according to the instruction [4] and verified that they work properly.

3. Use RGB-D Capture [1] to grab Kinect RGB and IR images with intensity.raw and depth.raw files. -> the software doesn’t grab IR images!! -> only RGB image, intensity.raw, depth.raw and calibration file (calibration.yml without distortion paraeters)!!

4. “calibrate-openni-intrinsics --pattern-size 0.025 grab1 calibration.yml” -> gives “openni_calibration.yml” with Intrinsic matrix and distortion coefficients for Kinect RGB camera !!

5. “calibrate-openni-depth.exe --pattern-size 0.025 grab1” gives partly processed figures with a message about errors.

21/11/2011

New Idea

5. MATLAB Inputs.

8/20

Cube_Curvatura_20110925\main_reproject.m

-> color.png (480x640 pixels)-> calibData.mat: - matrixes of intrinsic

parameters for IR camera (K_ir) and RGB camera (K_rgb)

- extrinsic mapping between ir (depth) and rgb Kinect camera (R,T)

- distortion coefficients (kc_ir, kc_rgb)

-> Points.mat (N x 6), where N – number of points with (x,y,z,R,G,B) info

21/11/2011

6. MATLAB Software.6.1 Elimination of the ground.

9/20

RANSAC search of the ground by using the plane equation.

21/11/2011

Transformation from IR (Depth) to RGB camera reference system:P_rgb = R * P_ir + T, where R,T - extrinsic mapping between ir and rgb Kinect cameras;

P_rgb, P_ir – points in RGB and IR camera reference systems.Cube Reprojection without considering distortion (up figures).

Cube Reprojection with considering distortion (bottom figures).10/20

6.2 3D Points Reprojection.

???Bad

calibration?

The distance from Kinect to the cube

z = 0.5 m

21/11/2011

Cube and Cylinder Reprojection without considering distortion (up figures).

Cube and Cylinder Reprojection with considering distortion (bottom figures).11/20

6.2 3D Points Reprojection.

???Bad

calibration?!

The distance from Kinect to the objects

z = 0.6 m

23/11/2011

Transformation from IR (Depth) to RGB camera reference system:P_rgb = R * P_ir + T, where R,T - extrinsic mapping between ir and rgb Kinect cameras;

P_rgb, P_ir – points in RGB and IR camera reference systems.Cube Reprojection with calibration parameters from Nicolo (upper figures).

Cube Reprojection with calibration parameters from Alberto (bottom figures).12/20

6.2 3D Points Reprojection.

Bad calibration?!

The distance from Kinect to the cube

z = 0.5 m

21/11/2011

Camera Calibration and 3d Reconstruction [9] for so-called pinhole camera model. The scene view is formed by projecting 3D points into the image plane using a perspective transformation.

where - are the coordinates of a 3D point in the world coordinate space. - are the coordinates of the projection point in pixels.A - matrix of intrinsic parameters (does not depend on the scene viewed). - a principal point (that is usually at the image center) - are the focal lengths expressed in pixel-related units.

R(T) - the matrix of extrinsic parameters.

Cube Reprojection with calibration parameters from Alberto (bottom figures).13/20

6.2 3D Points Reprojection.

21/11/2011

A R(T)

H

A = K_rgb R(T) = [R, T]

14/20

6.3 RANSAC fitting SQ to 3D data points.With using Levenberg-Marquardt algorithm of distance minimization from SQ to 3D

points.

Red points – outliers.Blue points – inliers.Green points – SQ model.

21/11/2011

15/20

6.3 Object structure creation and reprojection on image.

Reprojection of the lines between the 3D points of cube vertexes to CCD of Kinect RGB camera (figure a) and to the image with reprojected 3D points (figure b). The information about vertex position was obtained in the previous stage of RANSAC cube pose estimation.

Red lines – the cube frameworks

Figure a

Figure b

21/11/2011

9. References1. Nicolas Burrus. Kinect. RGBDemo, calibrate and visualize Kinect

output. // http://nicolas.burrus.name/, 2011. 2. OpenNI Modules. // www.openni.org, 3. SensorKinect drivers. // github social coding.

https://github.com/avin2/SensorKinect.4. How-to: Successfully install Kinect on Windows (OpenNI and

NITE). // Vangos Pterneas blog: http://studentguru.gr/b/vangos/archive/2011/01/20/how-to-successfully-install-kinect-windows-openni-nite.aspx

5. Install OpenKinect for Windows 7 and XP. // http://kinect.dashhacks.com/kinect-guides/2011/01/09/install-openkinect-windows-7-and-xp

6. Camera Calibration and 3d Reconstruction. // OpenCV (Open Source Computer Vision) v2.1 documentation: http://opencv.willowgarage.com/documentation/cpp/camera_calibration_and_3d_reconstruction.html

16/2021/11/2011