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Author Topic: Thermal camera  (Read 21302 times)

Wishgranter

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jedfrechette

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Re: Thermal camera
« Reply #16 on: March 13, 2013, 08:12:02 PM »
Here's another good video comparing rolling shutter in a Canon 5D and Sony Nex7:

http://www.mikekobal.com/blog/?p=4095

Notice how the buildings appear to tilt as the camera pans rapidly back and forth. That blog is discussing it in the context of shooting video but the same effect applies to stills.
Jed

RalfH

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Re: Thermal camera
« Reply #17 on: March 14, 2013, 11:29:38 AM »
Most point-and-shoot cameras (except for the very low end of the price range) have a mechanical shutter that ensures that the image is captured within a defined (short) time, so even if the sensor is read line-by-line (rolling shutter effect), this does not hurt if camera movement/rotation is small enough relative to the exposure time. From jedfrechette's link, this image shows the rolling shutter effect best: http://www.flickr.com/photos/42363616@N05/7012503063/.

For airborne systems, if you can't set the shutter speed to a pre-defined value (1/1000 or faster), you'll be asking for problems (whether they are rolling shutter type distortions or simply blurred images). 130 ms (i.e., approx. 1/8 s) is far too slow for an airborne platform unless there is IMU-based postprocessing (non-radial undistortion of the images based on very many very rapid measurements of camera rotations during image acquisition) or gyro-based camera stabilisation. In both cases, you'd probably want IMU/gyro update rates of approx. 1 kHz.

George

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Re: Thermal camera
« Reply #18 on: March 14, 2013, 07:58:29 PM »
That was cool explanation! Thanks Ralf.

George

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Re: Thermal camera
« Reply #19 on: March 15, 2013, 10:31:14 PM »
Ok. Today I tried AutoPano for the rolling shutter camera imagery (thermal) - perfect tho.
Now I am thinking what could be the camera with super fast shutter speed and time laps functionality instead of GoPro for VTOL model?
Any ideas, friends?

RalfH

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Re: Thermal camera
« Reply #20 on: March 15, 2013, 10:38:50 PM »
You can use almost any Canon point-and-shoot with CHDK (which allows you to run interval scripts on the camera). If you want to synchronise thermal and optical camera, time laps functionality would not be sufficient. Rather, you'd have to trigger both cameras simultaneously.