Simulate Long Exposure Time
Danh from United States  [79 posts]
9 year
Hi Steven,

Just got the commercial version for work. Wanted to show my boss a simple program where I could track a robot vac in the room to show its path. I have a webcam with wide angle lens mounted to the ceiling. I have done the dewarping and clipping but need help with creating the equivalent of a long camera exposure time like what was used below for capturing Roomba paths:


Can you provide a code snippet to simulate a long exposure time?

Steven Gentner from United States  [1446 posts] 9 year
The trick to these long exposures is to use something brighter than the background. See attached. Use a flashlight to draw a picture ... untoggle the Run button to clear and start again.


Danh from United States  [79 posts] 9 year
Thanks Steven.

Works pretty well. My robot is dark so I choose to track dark colored changes.

Would like to track just a small spot on the robot center. Gonna put a small IR light source on the bot and try to track it with an IR band pass filter over the camera. I'll use this as a mask to overlay over the orginal room snapshot. May need you help with that.


Steven Gentner from United States  [1446 posts] 9 year
Pretty cool image! That should be an interesting analysis.

What you can also try to do is to put a really bright LED on the robot and then really increase the shutter speed (or decrease the exposure time) on the camera to isolate just the LED light (common trick when working with lasers). That should get you a similar result with most of the image being dark. A simple Math module can then be used to take a regular image and the generated image and select the max of either ... that will compose the final result showing the trails on a regular intensity image.

Might be easier than dealing with IR filters.


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