Documentation.Calibration History
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!!! Calibrating with a projector
----
* [[TutorialProjectorKinectCalibration|Follow this tutorial]]
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build/bin/calibrate-kinect-ir --pattern-size 0.025 grab1/SERIAL
to:
build/bin/calibrate-kinect-ir --pattern-size 0.025 --input grab1/SERIAL
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Then here is an example of usage:
to:
Then here is a typical example of usage:
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./calibrate-openni-intrinsics --pattern-size 0.025 grab1 calibration.yml
to:
./calibrate-openni-intrinsics --pattern-size 0.025 grab1/SERIAL calibration-SERIAL.yml
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where SERIAL is the serial number of your camera.
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'''2.''' Grab some images of your chessboard using the viewer (File / Grab frame or Ctrl-G). WARNING: you need to grab images in Dual IR/RGB more (enable it in the Capture menu). By default it will save them into directories @@grab1/view????@@. These directories contain the raw files, @@raw/color.png@@, @@raw/depth.raw@@ and @@raw/intensity.raw@@ that corresponds to the color image, the depth image (in meters), and the IR image normalized to grayscale.
to:
'''2.''' Grab some images of your chessboard using the viewer (File / Grab frame or Ctrl-G). WARNING: you need to grab images in Dual IR/RGB more (enable it in the Capture menu). By default it will save them into directories @@grab1/SERIAL/view????@@. These directories contain the raw files, @@raw/color.png@@, @@raw/depth.raw@@ and @@raw/intensity.raw@@ that corresponds to the color image, the depth image (in meters), and the IR image normalized to grayscale. SERIAL should be the serial number of your camera.
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build/bin/calibrate_kinect_ir --pattern-size 0.025 grab1
to:
build/bin/calibrate-kinect-ir --pattern-size 0.025 grab1/SERIAL
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This will generate the @@kinect_calibration.yml@@ file storing the parameters for the viewer, and two files @@calibration_rgb.yaml@@ and @@calibration_depth.yaml@@ for ROS compatibility.
'''Note with Mac binaries''': if there is a @@grab1@@ directory in the current directory, it will be loaded automatically.
'''Note with Mac binaries''': if there is a @@grab1@@ directory in the current directory, it will be loaded automatically
to:
This will generate the @@calibration-SERIAL.yml@@ file storing the parameters for the viewer, and two files @@calibration_rgb.yaml@@ and @@calibration_depth.yaml@@ for ROS compatibility.
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'''1.''' Build a calibration pattern as shown in [[KinectCalibration]]. You can use the @@Chessboard_A4.pdf@@ or @@Chessboard_A3.pdf@@ file in the @@data/@@ directory for this. I recommend printing the chessboard on a sheet of paper and glue it on a peace of carton. It is not necessary anymore to cut the carton around the paper.
to:
'''1.''' Build a calibration pattern as shown in [[KinectCalibrationTheory]]. You can use the @@Chessboard_A4.pdf@@ or @@Chessboard_A3.pdf@@ file in the @@data/@@ directory for this. I recommend printing the chessboard on a sheet of paper and glue it on a peace of carton. It is not necessary anymore to cut the carton around the paper.
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!!! Calibrating your Kinect (`OpenNI backend)
----
'''New since `RGBDemo v0.5.0''': if you are using the `OpenNI backend, then the calibration parameters will be determined automatically.
Note: you might first want to read the previous section to get an overview of the calibration system.
`OpenNI comes with a predefined calibration stored in the firmware that can directly output aligned depth and color images with a virtual constant focal length. Most applications will be happy with this calibration and do not require any additional step. However, some computer vision applications such as robotics might need a more accurate calibration. `RGBDemo comes with two utilities to refine the predefined calibration.
!!!! Using @@calibrate-openni-intrinsics@@
This program takes as an input a set of images with a checkerboard, as output by @@rgbd-viewer@@. It also takes the initial calibration file, which can be created using @@File/Save calibration file@@ in @@rgbd-viewer@@.
Then here is an example of usage:
[@
./calibrate-openni-intrinsics --pattern-size 0.025 grab1 calibration.yml
@]
The @@openni_calibration.yml@@ file should contain the refined parameters.
!!! Calibrating your Kinect (libfreenect backend)
----
'''Note:''' this is only necessary if you want to use the libfreenect backend.
A sample calibration file is provided in @@data/kinect_calibration.yml@@. However, you should be able to get a more accurate mapping by estimating new parameters for each Kinect. Below is the procedure I follow.
'''1.''' Build a calibration pattern as shown in [[KinectCalibration]]. You can use the @@Chessboard_A4.pdf@@ or @@Chessboard_A3.pdf@@ file in the @@data/@@ directory for this. I recommend printing the chessboard on a sheet of paper and glue it on a peace of carton. It is not necessary anymore to cut the carton around the paper.
'''2.''' Grab some images of your chessboard using the viewer (File / Grab frame or Ctrl-G). WARNING: you need to grab images in Dual IR/RGB more (enable it in the Capture menu). By default it will save them into directories @@grab1/view????@@. These directories contain the raw files, @@raw/color.png@@, @@raw/depth.raw@@ and @@raw/intensity.raw@@ that corresponds to the color image, the depth image (in meters), and the IR image normalized to grayscale.
To get an optimal calibration, grabbed images should ensure the following:
* Cover as most image area as possible. Especially check for coverage of the image corners.
* Try to get the chessboard as close as possible to the camera to get better precision.
* For depth calibration, you will need some images with IR and depth. But for stereo calibration, the depth information is not required, so feel free to cover the IR projector and get very close to the camera to better estimate IR intrinsics and stereo parameters. The calibration algorithm will automatically determine which grabbed images can be used for depth calibration.
* Move the chessboard with various angles.
* I usually grab a set of 30 images to average the errors.
* Typical reprojection error is < 1 pixel. If you get significantly higher values, it means the calibration probably failed.
'''3.''' Run the calibration program:
[@
build/bin/calibrate_kinect_ir --pattern-size 0.025 grab1
@]
The pattern size correspond to the size in meters of one chessboard square. It should be 0.025 (25mm) for the A4 model.
This will generate the @@kinect_calibration.yml@@ file storing the parameters for the viewer, and two files @@calibration_rgb.yaml@@ and @@calibration_depth.yaml@@ for ROS compatibility.
'''Note with Mac binaries''': if there is a @@grab1@@ directory in the current directory, it will be loaded automatically.
----
'''New since `RGBDemo v0.5.0''': if you are using the `OpenNI backend, then the calibration parameters will be determined automatically.
Note: you might first want to read the previous section to get an overview of the calibration system.
`OpenNI comes with a predefined calibration stored in the firmware that can directly output aligned depth and color images with a virtual constant focal length. Most applications will be happy with this calibration and do not require any additional step. However, some computer vision applications such as robotics might need a more accurate calibration. `RGBDemo comes with two utilities to refine the predefined calibration.
!!!! Using @@calibrate-openni-intrinsics@@
This program takes as an input a set of images with a checkerboard, as output by @@rgbd-viewer@@. It also takes the initial calibration file, which can be created using @@File/Save calibration file@@ in @@rgbd-viewer@@.
Then here is an example of usage:
[@
./calibrate-openni-intrinsics --pattern-size 0.025 grab1 calibration.yml
@]
The @@openni_calibration.yml@@ file should contain the refined parameters.
!!! Calibrating your Kinect (libfreenect backend)
----
'''Note:''' this is only necessary if you want to use the libfreenect backend.
A sample calibration file is provided in @@data/kinect_calibration.yml@@. However, you should be able to get a more accurate mapping by estimating new parameters for each Kinect. Below is the procedure I follow.
'''1.''' Build a calibration pattern as shown in [[KinectCalibration]]. You can use the @@Chessboard_A4.pdf@@ or @@Chessboard_A3.pdf@@ file in the @@data/@@ directory for this. I recommend printing the chessboard on a sheet of paper and glue it on a peace of carton. It is not necessary anymore to cut the carton around the paper.
'''2.''' Grab some images of your chessboard using the viewer (File / Grab frame or Ctrl-G). WARNING: you need to grab images in Dual IR/RGB more (enable it in the Capture menu). By default it will save them into directories @@grab1/view????@@. These directories contain the raw files, @@raw/color.png@@, @@raw/depth.raw@@ and @@raw/intensity.raw@@ that corresponds to the color image, the depth image (in meters), and the IR image normalized to grayscale.
To get an optimal calibration, grabbed images should ensure the following:
* Cover as most image area as possible. Especially check for coverage of the image corners.
* Try to get the chessboard as close as possible to the camera to get better precision.
* For depth calibration, you will need some images with IR and depth. But for stereo calibration, the depth information is not required, so feel free to cover the IR projector and get very close to the camera to better estimate IR intrinsics and stereo parameters. The calibration algorithm will automatically determine which grabbed images can be used for depth calibration.
* Move the chessboard with various angles.
* I usually grab a set of 30 images to average the errors.
* Typical reprojection error is < 1 pixel. If you get significantly higher values, it means the calibration probably failed.
'''3.''' Run the calibration program:
[@
build/bin/calibrate_kinect_ir --pattern-size 0.025 grab1
@]
The pattern size correspond to the size in meters of one chessboard square. It should be 0.025 (25mm) for the A4 model.
This will generate the @@kinect_calibration.yml@@ file storing the parameters for the viewer, and two files @@calibration_rgb.yaml@@ and @@calibration_depth.yaml@@ for ROS compatibility.
'''Note with Mac binaries''': if there is a @@grab1@@ directory in the current directory, it will be loaded automatically.