Acoustic Localization Using Mobile Platforms

1
Motion Detection and Processing Performance
AnalysisThomas Eggers, Mark Rosenberg Department
of Electrical and Systems Engineering
Histograms
Methods
Abstract
This project involved designing motion detection
software. LabVIEWs NI Vision and Motion software
was used to implement the detection. A Firewire
camera was used to feed the video to the
computer. The software developed has the
capabilities of not only reading live camera feed
but can also read any AVI file. The software has
the ability to detect motion, place a red circle
on the center of the region of detected motion,
and saves the motion file to a hard drive. The
camera operates at 60 fps, and while no motion is
detected, the software processes 45 fps. When
motion is detected, the software slows, only
writing roughly 30 frames per second. The
software includes a GUI which shows the live
feed, and displays where the files will be saved.
The detection is also customizable, allowing the
user to select the threshold values for when
motion is detected, depending on the specific
need of the user.
1 Acquisition AVI CAM
No Motion

4. This option allows the user to write the CAM
to AVI unprocessed for comparison with the
processed AVI. This pair of unprocessed/processed
AVI files can also be compared with the
corresponding pair from AVI input.
6. The previous frame is copied to a new path and
compared to the current image. The pixels of the
resulting image have grayscale values that
reflect the difference between the current and
previous images.
5. The image is copied to a new path and
converted to grayscale (U8) so that differences
between frames are simplified to one parameter.
3. The Vision Acquisition subVI grabs frames from
either the AVI or the CAM each loop cycle.
2 Subtract AVI CAM
No Motion

2. First, a path is designated for the processed
video output.
7. The image is filtered by a threshold and each
pixel is represented by a black or red bit.
8. The centroid is calculated for all pixels
above the threshold, and the coordinates are
calculated for the circle which will be overlaid
onto the output images.
1. The VI has two modes, AVI and CAM, which are
selected for with a Boolean switch.
3 Threshold AVI CAM
No Motion

9. The number of pixels that showed motion above
the threshold is calculated and stored.
10. If the last 8 frames average at least 150
changed pixels, then a Boolean is toggled for
processing the motion.
Results
14. After the input AVI file is done being
processed, or the CAM is stopped, the VI ends.
This table shows a summary of average times for
each part of the analysis.
4 Centroid AVI CAM
No Motion

12. The circle is overlaid at the centroid of the
motion.
13. The processed frame is written to an AVI
output file.
11. The original frame is cleared from any
overlays and a timestamp is overlaid at constant
coordinates.
15. The frame rate of the output AVI is set to
the same for AVI input and 20 for CAM input.
16. The VI is separated with a sequence structure.
AVI CAM
Motion Motion No Motion No Motion Motion Motion No Motion No Motion
Components Avg (ms) Std Dev Avg (ms) Std Dev Avg (ms) Std Dev Avg (ms) Std Dev
Acquisition - - 33.6 8.57 - - 19.7 1.26
Subtract - - 0.437 0.497 - - 0.506 0.4999
Threshold - - 0.317 0.464 - - 0.144 0.351
Centroid - - 0.566 0.496 - - 0.485 0.499
Quantify - - 2.02 0.149 - - 2 0.162
Write AVI 8.34 1.93 0 0 9.12 2.1 0 0.0258
Sum 45.28 36.94 31.955 22.835
18. The difference in time between two timers is
calculated.
19. If it is greater than the maximum or less
than the minimum, it replaces them.
17. Timers flank regions whose performance is
being analyzed.
5 Quantify AVI CAM
No Motion

20. Each loop cycle, differences are added to an
array.
6 Write AVI AVI CAM
No Motion
Motion
21. The array is represented with a histogram.
Acknowledgements
22. Averages and standard deviations are
calculated from the array.
We thank Dr. Robert Morley, Ed Richter, Kristen
Heck, National Instruments, the Department of
Electrical and Systems Engineering, and
Washington University in St. Louis