1. Matterhorn Unconference 2014 Lets fix it in post! Ideas for
automated post-recording video handling Stephen Marquard University
of Cape Town 19 March 2014
2. Why post-process video? A different approach to solving the
blackboard challenge Improve video quality Close-ups More natural
perspectives Avoid challenging lighting conditions (e.g.
projection) Smooth motion (perfect knowledge of the future) Adjust
for optimal colour / white balance / contrast Cost Multiple fixed
HD IP cameras for half the cost of a PTZ camera / solution
3. Cost + + < Bosch Dinion HD832 IP camera Vaddio ClearVIEW
HD-USB IP camera
4. The blackboard challenge How to get useful video where
blackboard writing and diagrams are legible in large, wide
venues
5. Avoid sightline problems
6. A real-time blackboard solution LectureSight: Direct a PTZ
camera to follow the presenter, using real-time image analysis from
an overview camera. https://opencast.jira.com/wi
ki/display/LECTURESIGHT /LectureSight+Project+Ho me
7. A post-processing presenter solution
http://wiki.teltek.es/display/GaliTracker/GaliTracker+Home
GaliTracker does cropping and zooming from a fixed HD image to give
a presenter closeup
8. Multiple fixed cameras 1
9. Multiple fixed cameras 2
10. Multiple fixed cameras 3
11. Post-processing The capture agent records multiple camera
streams (probably IP cameras): the mediapackage has 2, 3 or 4
presenter videos rather than 1. The camera streams are then
post-processed to create a single presenter video (perhaps on the
CA itself) Approaches: 1. Virtual panning (combine and crop) 2.
Mixing (source selection)
12. Virtual panning Left camera frame Centre camera frame Right
camera frame Single panoramic image constructed from 3 fixed camera
images Wide frame is cropped to position the presenter optimally
(two-pass approach) Pros: smooth motion, optimal view. Cons:
stitching images may be tricky, shifting perspectives.
13. Mixing from multiple sources Image analysis and two-pass
approach to select transition points between cameras (switch or
cross-fade). Left camera Centre camera Right camera Selected
camera
14. Other post-processing ideas Improve colour, white balance
and contrast dynamically or per region in the image. Compensate for
the effect of projector image in the frame, and poor presenter
lighting.
15. Other post-processing ideas Improve image perspective and
geometry Correct for fishbowl and other disturbing lens and camera
positioning artefacts
16. What next? Get involved! Good project topics for students.
Share your ideas and possible contributions on the Matterhorn
list(s).