[talk-au] NearMap PhotoMap imagery for OSM

[Peter Ross]

On Thu, Nov 12, 2009 at 1:07 PM, John Smith <deltafoxtrot256 at gmail.com> wrote:
> 2009/11/12 Peter Ross <peter at emailross.com>:
>> It's great, but I at least in this location it's out by about 3-5m.
>
> Considering that's bordering on GPS accuracy it's kind of hard to tell
> the actual accuracy that way.
>
Sure if you only have one GPS track for that location, however I have
multiple gps tracks taken on different days over about 2 months, so
I'm assuming that using the mid point of all of those traces should be
where the track is.  If you use josm and download the gps traces for
the region I'm talking about you should be able to see what I mean.


> Brendan did some comparisons with the property boundaries in QLD and
> came up with an accuracy of 1-4m.
>
Ben Last from nearmap got in contact with me after I posted the above
on the nearmap wikipage and I quote:

"We'd like to find out what sort of errors you're seeing.  The
Melbourne survey wasn't flown with precision GPS due to a fault, but
it shoudl still be within 5m or  so absolute."

After that I did some more accurate measuring and the underlying
imagery needed to be moved 6m east and 3m south  and then it all lined
up extermely well.

>> However the actual imagery is fan-bloody-tastic!
>
> Considering other imagery sources are out 20+ m in places so is the accuracy :)
>
It's the problem of having such good imagery, when things are out it's
much more noticeable.