[OSM-talk] unkown coordinate encoding
Nick Hill
nick at nickhill.co.uk
Mon Mar 27 21:59:15 BST 2006
You may also find the numbers change substantially when you go west of
the meridian.
West co-ordinates are negative.
It is likely that in your format, the most significant bit will either
simply flag west of the meridian, or the number will be expressed in 2's
complement. 2's complement is the most likely, and is a little more
confusing.
For more information on binary negation, see:
http://www.math.grin.edu/~rebelsky/Courses/152/97F/Readings/student-binary.html#neg
Nick Hill wrote:
> Actually, the number should probably be
> 8388608
>
> which is the nearest whole number in the 2^x series. So by shifting the
> binary number 23 bits to the right, you get the integral. The least
> significant 23 bits are the fractional.
>
>
>
> Nick Hill wrote:
>
>> Hi Ovidiu
>>
>> Just divide the numbers by 8388611 to get the regular lat/lon
>> co-ordinates.
>>
>> so
>> 373101418 becomes 44.477
>> 219065058 becomes 26.114
>
>
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