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Re: [grassrootsmapping] Re: altitude from battery/sensor temperature


Jeffrey Warren Feb 10, 2012 1:08 PM
Posted in group: grassrootsmapping
Cool, i extracted temperatures and times and graphed them:

http://publiclaboratory.org/notes/warren/2-10-2012/temperature-during-thatchmore-farms-flight

Kinda weird, it goes up towards the middle of the flight.

On Fri, Feb 10, 2012 at 1:07 PM, andrzej zaborowski <bal...@gmail.com> wrote:
> On 10 February 2012 18:53, andrzej zaborowski <bal...@gmail.com> wrote:
>> On 10 February 2012 15:56, Jeffrey Warren <je...@publiclaboratory.org> wrote:
>>> I checked a set of images from a Canon a490, and didn't see
>>> temperature... maybe it's the EXIF program I'm using, "exif" (linux).
>>> Attached is the output and the first image of the flight. Ideas?
>>
>> My desktop is down and I'm on travel, so I went installing all of the
>> exif readers for Linux on the netbook and it seems like each one gives
>> you a different set of tags.  "exiftool" is the only one that gives me
>> the temperature and a whole lot of other things the other programs
>> don't.
>>
>> For the example image it says 31C, pretty hot :)
>>
>> The theory is that, on average and up to some altitude, temperature
>> decreases 1C per 100m up.
>
> By the way the cameras also save the target distance in EXIF.  I don't
> know how it is measured technically, but in low flights (assuming the
> camera is pointing down, is not set to focus on infinity, and is below
> 65.536 m from the ground), it'll surely give you better accuracy.
>
> Cheers