DonQx wrote:some would disagree
seen this discussion: http://www.gpsaustralia.net/forums/showthread.php?t=7074&s=3f05127e0ca3f195075046b812e7be7e&p=34547#post34547 ?
Ent wrote:Found out that the Government has access to 1 arc measurement but this is or maybe was for sale only to commercial users and government departments so it is likely that some commercial maps use this.
Ent wrote: Hopefully some nice German will help me out what I am doing wrong.
sthughes wrote:Would it be possible to create an OSM map set that has a transparent background to overlay on the Garmin maps? So say an OSM set that does not have the rivers and lakes etc, but does have the tracks, mountains peaks etc to supplement the areas of the Garmin Maps that are lacking?
Ent wrote:DonQx wrote:some would disagree
seen this discussion: http://www.gpsaustralia.net/forums/showthread.php?t=7074&s=3f05127e0ca3f195075046b812e7be7e&p=34547#post34547 ?
The base data for Contours Australia comes from the NASA SRTM data that for Australia uses 3 arc (90 metre) measurements. Found out that the Government has access to 1 arc measurement but this is or maybe was for sale only to commercial users and government departments so it is likely that some commercial maps use this. The basic issue with Contours Australia 5M is they convey a degree of precision that they simply do not have. You see nice slopes rather than cliffs. Also they slow down a GPS and result in screen clutter. The one arc set stand a better chance of picking the high points and the extrapolation would be better but I have no idea what commercial products use them. They still would be only "true" thirty metre data. Also I think Tasmap has their own data from years of measurement so nothing can be a Tasmap for find a cliff but they are still guesstimates.
But if you are ever up in Launceston I have them so you can as well. They are around 2GB for Australia. I am working on downloading them direct from NASA in any level needed but as usual struck the geek language barrier. Hopefully some nice German will help me out what I am doing wrong.
. . . .
The basic issue with Contours Australia 5M is they convey a degree of precision that they simply do not have. You see nice slopes rather than cliffs
Do you need to know the true extent to the nearest 5 metre of every hill and hummock?
DonQx wrote:totally agree! thx for your thoughts, nicely stated
Used to run bushnavigation courses for years, based on the "use your grey matter" and habit of "constant thought & observation" philosophy.
Re.Do you need to know the true extent to the nearest 5 metre of every hill and hummock?
No, bUUUt ... in some more undulating areas, like the Plateau, I wouldn't mind having contours a bit better than 20m based on varying degrees of guesswork. Unlikely to happen in a hurry I presume, but would be nice to end up with fairly good say 10m contours at some stage in the future.
dq.
Don Quixote ... fully titled The Ingenious Gentleman Don Quixote of La Mancha
DonQx wrote:HEE- HAWWH!
Wind farms? ... we have our moments ...
dq.
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