I will do a resurvey in the way you suggest. It was really disappointing to find I couldn't trust my GPS at all (well, I did some mental adjustment of waypoints to place building entrances), and being off by a constant amount for 4 km certainly makes one suspicious.

A bit to the north, my GPS survey of some footpaths behind a school matched Bing nicely. It would be really interesting to find some sort of disconnect in between.

Je manquais de la courtoisie envers les francophones qui suivent cette liste. En sommaire, j'ai tracé une piste de longueur totale environ 4 km, mais l'a trouvé toujours environ 10 metres à l'ouest des entités déja presents sur la carte et les images Bing. Je vais faire un autre sondage pour mieux comprendre la situation.

Tom Taylor

On 19/11/2012 8:37 AM, Connors, Bernie (SNB) wrote:
Tom,

The transmission lines would not affect your GPS accuracy.  I agree
with Pierre that you could repeat the track and see if the two tracks
are similar.  Another thing you could do is identify several
identifiable points in the Bing Imagery such as the intersection of
two sidewalks, the corner of a sports field, etc.  Go to those points
and use your GPS to record a waypoint and use position averaging with
about 3 minutes of recording to get a more accurate location and then
compare those waypoints to the Bing imagery.  Position the Bing
imagery so they match up with your waypoints and then look at your
GPS tracks top see how they line up with the Bing Imagery.

Bernie. -- Bernie Connors, P.Eng Land Information Infrastructure
Unit, SNB bernie.conn...@snb.ca

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