Vicon Vantage V8 Status Active Superusers Ivan Penskiy (ipenskiy[at]umd[dot]edu) Important documents and useful links Technical specs Vantagte camera reference guide Vicon Tracker guide Vicon models and scripts Overview Vicon is a motion capture optical system that allows for tracking, recording, and analysis of passive reflective markers mounted on a subject of interest. The system consists of 12 Vantage V8 cameras that are mounted to cover the majority of netted space volume in the Brin Drone Lab. Measurement accuracy depends on the location in the netted area but typically is under 1 mm. Software setup Vicon Tracker software is installed on Windows 10 PC. The tracking data can be collected by ROS over local network using vicon_driver. Location Brendan Iribe Center 432, Room 0108. Reservation The Vicon motion capture system must be reserved before using. The reservation is done using the Google calendar (IRB-0108vi). You will be able to reserve the equipment personally after attending the Brin Drone Lab orientation and then following the steps below to gain access to the equipment. <!--cke_bookmark_104S--><!--cke_bookmark_104E--><!--cke_bookmark_124S--><!--cke_bookmark_124E--><!--cke_bookmark_313S--><!--cke_bookmark_313E--><!--cke_bookmark_100S--><!--cke_bookmark_100E--> Video demonstration The following videos demonstrate capabilities and the some aspects of operating Vicon motion capture system: Object tracking UAV showcase Human Gate Capture Note: these are promotional and instructional videos. They are included for demonstrational purposes only. The details of actual operational procedures in the Brin Drone Lab can differ! Important reminders Vicon cameras require reaching their steady operating temperature for best performance. Turn ON the cameras 30-45 min before starting the calibration procedure or motion capture. If the Vicon cameras are not being used for data acquisition for longer than 3 hours, the switch powering the cameras should be turned OFF; the computer which controls the Vicon cameras can be left on to maintain your work state. Working with Tracker software This is a collection of some recommendations for the Tracker software, the full user guide can be downloaded here. Video demonstrating the calibration procedure. Video demonstrating the process of creating objects and recording trials. Some mouse and keyboard shortcuts F5 Display full screen view for the selected view pane F7 Display/Close Options dialog box Ctrl + T Create named object from selected reconstructions Ctrl + S Save all Space Pause Live/Play Offline Ctrl + Z Undo Ctrl + Y Redo T Translate object R Rotate object Right-click + drag forward or backward Dolly/Zoom. Move camera viewpoint closer to or further away from the focal point Left-click + drag left, right, forward, or backward Orbit. Move camera viewpoint around the focal point Click wheel button + drag left, right, forward, or backward Truck/Translate. Move camera viewpoint along a horizontal or vertical axes Ctrl + Shift + Z Zoom the camera viewpoint to the sensor window System tab settings It is recommended to keep the Tracker capture settings at their default values but in some tests (e.g. capturing very fast moving objects) some of the variables should be adjusted. Make sure to restore the default values when you are done with the tests. Requested Frame Rate. Default value: 100. The rate (in Hz) at which to synchronize the Vicon cameras and the external video signal. Select from displayed values up to a maximum of 2,000. The configured Vicon system capture rate is displayed in square brackets beside the Local Vicon System node. For example, if the Vicon system frame rate is set to 100 Hz, the node title is displayed as Local Vicon System [100Hz]. Low Jitter. Default value: yes. When selected, sets the Grayscale Mode for all cameras to Only, which applies advanced centroid fitting and jitter reduction algorithms to reduce data noise. Note that running in this mode increases sensitivity to bandwidth limitations and its effectiveness is related to system size. Gain. Default value: 1. The amplification of the pixel value. Select a displayed value to determine the intensity of the grayscale from the Vicon cameras: x1, x2, x4, or x8. This setting is applied to the camera to change the dynamic range of the recorded image. Increasing the Gain means that the marker has less variation in grayscale intensity between its center and its edge, but in certain circumstances, using a higher gain yields markers that are easier for the camera to distinguish. Adjust this setting if the markers appear too faint or if the cameras have trouble distinguishing them; otherwise, leave the this property at the default x1 setting. Strobe Intensity. Default value: 1. The amount of light emitted by camera strobe units. This value can be set between 0-1 to minimize reflections and obtain clear marker images. The higher the setting, the brighter the markers appear, but this may cause blobs to be produced from reflections from other strobes. Lower settings make the markers themselves less visible to the cameras. In almost all circumstances, you will want to keep the intensity at its maximum level because the system works by recording light from the strobes that is reflected from the markers, thus the more light the strobes send out the more light the markers reflect. However, if you are capturing a very fast moving object you may achieve better results by reducing the strobe intensity. The strobe intensity affects the time the strobe is on for each camera frame. The full strobe intensity corresponds to 1 ms for normal frame rates. Lower strobe intensities mean that the markers are captured with the strobes on for less time and, therefore, have less time to move during the frame. Sensor Mode. Default value: Normal. Tracker 3.9 and later supports the use of the Vantage+ firmware upgrade, enabling you to use High Speed mode on your Vantage cameras without having to change the field of view (FOV) or lens. When you capture optical data, subsampling (selectively reducing the pixel count) enables you to run at high camera frame rates without reducing the FOV (frame size). In High Speed mode, you can run your Vantage cameras at higher frames rates while maintaining the FOV. You can change frame rates during capture and you do not need to set up your cameras again when you increase the frame rate, as the FOV is unchanged. Because the higher speeds are achieved through subsampling (removing some pixels from the frames), some reduction in resolution is incurred. For details, see High-speed mode in the Vicon Vantage Reference Guide. Reconstruction Minimum Separation. Default value: 10. The minimum distance, specified as a value in the range 0–100 mm, allowed between 3D marker positions in order for them to be considered for reconstruction. If two candidate reconstructions are closer than this minimum separation, only the most likely reconstruction (in terms of the number of cameras contributing) will be reported. The other will be discarded. A higher value decreases the likelihood of creating spurious reconstructions, but increases the possibility that some genuine markers will not be reconstructed. To disable this feature, set the value to 0.0. Centroid Threshold. Default value: 0.2. The minimum brightness (intensity) for markers; pixels of an intensity lower than this threshold are ignored. This value can be set between 0-1 to determine the pixels to be considered for centroid fitting onboard the Vicon cameras. Lower settings enable the camera to detect lower light levels, thus making the markers appear larger, but may pick up unwanted reflections and other light sources. Higher settings reduce the noise, but make the markers themselves less visible. This setting differentiates between markers and ambient light. A Vicon camera records 10-bit grayscale data, which for each sensor pixel is a measure of how much light fell on that pixel during a given amount of time. However, the cameras will almost always pick up some ambient light in the volume. To enable the cameras to distinguish between light that comes from markers and light that does not, a threshold is applied. Anything above this threshold is deemed to be a marker, anything below is deemed to be ambient light. A value in the region of 0.2 to 0.5 is usually appropriate, but Vicon strongly recommends that you use static markers in the volume in order to establish an appropriate setting. If cameras are evenly spaced around the volume, the same threshold value is usually sufficient for all cameras. Centroid Minimum Circularity Ratio. Default value: 0.5. The circularity threshold used by the centroid-fitting algorithms in a Vicon camera. (Note that this mode is disabled if Low Jitter mode is selected.) This value can be set between 0-1 to determine how similar a grayscale blob must be to the internal model of a marker – that is a radially symmetric object that has smooth, sharp edges and whose pixel intensity is brightest at the center and gradually fades towards the edges. The Vicon cameras consider grayscale blobs with circularity equal to or greater than this threshold to be well-formed, circular marker images. The higher the value, the more stringent the centroid fitter is; the lower the value, the less stringent the centroid fitter is. You may want to apply higher settings for camera calibration to ensure that Tracker selects the best markers and thus provides the best possible calibration. A lower value may be appropriate for data capture. Maximum Blob Height. Default value: 50. The maximum number of pixels per line that a grayscale blob can contain in a horizontal line. If the number of pixels exceeds this value, the Vicon camera determines that the grayscale blob is not a marker, stops processing it, and discards the pixel values (it preserves just the coordinates data, which can be sent to Vicon Tracker, depending on the Grayscale Mode setting). Set this value between 0–77500 to determine how large a grayscale blob can be for a Vicon camera to consider it a candidate marker. The Vicon cameras consider grayscale blobs with horizontal lines containing this number or fewer pixels to be good-sized, circular marker images. The higher the value, the larger a grayscale blob can be; the lower the value, the smaller a grayscale blob must be. Gaining access to equipment Preparation Scheduling Instruction session Preparation: Familiarize yourself with Vicon Tracker software using either the official guide or another tutorial. Scheduling: Once you are confident in the topics from the previous section, email the lab manager (Ivan Penskiy, ipenskiy[at]umd[dot]edu ) to schedule the instruction session (30–45 min). Instruction session: During the instruction session the user will be instructed on the main steps of operating the Vicon system in the Brin Drone Lab (software setup, startup, system calibration, operation, shutdown).