[Canberrauav] Raspberry Pi Camera Lag Testing

Bruce Baxter brucebaxtersolutions at gmail.com
Thu Feb 1 00:57:58 AEDT 2018


As a side question here, 
Has anyone tried using an iPhone and triggering it with a servo on the volume button?
It has its own gps and time tagging and can automatically upload to "cloud" storage via wifi or cell data. 
It may be more accurate being all integrated. 

Also, the flirone clip on for a cellphone may function the same way.

Sent from my iPad

> On 31 Jan 2018, at 11:24 PM, Carlos Peco-Berrocal <carlos.peco at gmail.com> wrote:
> 
> Stephen,
> 
> What about the time it takes the "time" to appear in the video output
> of the TV? Is that a constant ?
> 
>> On 1/31/18, Stephen Dade <stephen_dade at hotmail.com> wrote:
>> Hi all,
>> 
>> I attempted some measurements of the Raspberry PiCam + cuavraw camera lag.
>> It was fairly crude - I pointed the PiCam at my TV, which was displaying the
>> "time" bash command from the Pi, with cuavraw running in a screen session in
>> the background.
>> 
>> Attached is a (cropped to reduce file size) example image I captured. From
>> the image, I did have some trouble with the terminal/screen refresh rate and
>> the PiCam capturing. This meant that I couldn't use ~20% of the images I
>> captured.
>> 
>> For the remaining images where I could pick out the latest timestamp my
>> results were:
>> Console time lagging the camera time by 600 - 800 milliseconds
>> 
>> Given that cuavraw tags the image timestamps after image capture (but prior
>> to debayering and jpg encoding), this would indicate that there's a
>> 600-800ms time lag between the camera shutter capturing the image and the
>> Raspberry Pi downloading the image from the camera.
>> 
>> If we were flying at 30m/s, this would equate to a 18-24m error in our
>> georeferencing.
>> 
>> 
>> 
>> Thanks
>> Stephen
>> 
>> 
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