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VisionWorks Toolkit ReferenceSeptember 29, 2015 | 1.0 Release |
Feature Tracker Demo user guide.
nvx_demo_feature_tracker
is a simple local feature tracking demo that uses the Harris feature detector to get the initial list of features and tracks them using the sparse pyramidal optical flow method (Lucas-Kanade).
In the first frame, Gaussian pyramid is created and initial points are detected:
(frame) | [ColorConvert] | +-------------------+-------------------+ | | [GaussianPyramid] [HarrisTrack] | | (initial pyramid) (initial points)
In subsequent frames, points are tracked with the Lucas-Kanade method between two pyramid images. Then, corner detection is performed to restore lost points.
The NVIDIA extended Harris Corner function divides the image into cells of the same size and looks for corners independently in each cell. In this way, corners are uniformly detected across the image. These corners are the keypoints that are tracked in the next frames.
(frame) | [ColorConvert] | [ChannelExtract] | [GaussianPyramid] | (previous pyramid) (current pyramid) (points to track in the previous frame) | | | +------------------------------+--------------------------------------+ | [OpticalFlowPyrLK] | (tracked points) | [HarrisTrack] | (points to track in the next frame)
nvx_demo_feature_tracker
is installed in the following directory:
/usr/share/visionworks/sources/demos/feature_tracker
For the steps to build sample applications, see the Sample and Demos User Guides section for your OS.
./nvx_demo_feature_tracker [options]
This topic provides a list of supported options and the values they consume.
--source=/path/to/video.avi
for video--source=/path/to/image.png
for image--source=/path/to/image_%04d_sequence.png
for image sequence--source=device://camera0
for the first camera--source=device://camera1
for the second camera.sudo
.Description: Specifies the path to the configuration file. The file contains the parameters of the algorithm stored in key=value format. Note that the config file contains information on the intrinsic parameters of the camera, so using the default config file for different videos may sometimes give a result with insufficient quality.
This file contains the following parameters:
Usage:
./nvx_demo_feature_tracker --source=/path/to/video.avi --config=/path/to/config_file.yml
Space
to pause/resume the demo.ESC
to close the demo.