[OSM-talk] JOSM update

[David Earl]

On 28/03/2008 18:00, Frederik Ramm wrote:
> Hi,
> 
>> | I believe that they are sorted by timestamp. What they aren't sorted
>> | by is the track they came from so you might get points jumbled up from
>> | different tracks.
>> |
>> | The API deliberately tries to expose limited information about the
>> | points for privacy reasons as some points may have come from traces
>> | that are not public.
>>
>> Why expose the timestamps of private tracks. Expose the order, but
>> please don't expose the timing
> 
> That's exactly what happens. They are sorted by timestamp, but what's 
> returned is only the latitude and longitude.
> 
> (If I were really bent on finding out the exact timestamp of a certain 
> GPS point, I could do a "binary search attack" by uploading a trace that 
> contains a point in the area I'm interested in, with a timestamp of, 
> say, 2 years ago. Then download the GPS trace and see if my point is 
> before or after the point I am interested in. Then upload another trace 
> with a test point one year later or earlier, and so on. I would probably 
> have to upload about 10 points to know exactly which day the GPS point 
> was recorded on, and 5 more to know the hour of the day. But that would 
> really be vandalism...)

I should point out that you can't synchronize an audio track to a GPS 
track without the exact timing information.

But I'm confused now - if I look at GPS tracks on the third tab of the 
OSM home page, what I see is GPX style HTML with exact timestamps and 
ordered tracks. So if it is public there why suppress it when accessed 
through another route.

I'm also bemused why people are concerned about making this public anyway.

David