[Proj] X,Y UTM distance calculation (compare with latlong WGS84)

[marco vieira]

Oon:
 My sugestion:
  1) Convert to degrees
  2) Calculate distance with a  geodesic algorithm (Vicenthy, Puissant,
etc).

 You can't use this distance to irradiate new UTM points (distance + angle +
source point = second point) because UTM distance are "projected" (with
controled distortion). To make this you must project this distance with
local + ellipsoid parameters.

I Don't know about distance calculation with proj4 tools
There is manual methods to "zone transposition", but my sugestion is more
simple and generic than it.

When you talk about WGS84 you talk about "datum", not "projection". UTM is
used too with WGS84 datum.
You only calculate distance with cartesian formula using latlong coordinates
with you don't care about hundred meters of error but if you dont care about
probaly you are talking about much kilometers, than maybe you get thousand
meters of erros using this.


Regards
-- 
Marco Vieira
+55 21 9499-6800
e-mail: maovieira at gmail.com

2006/9/13, oon at informatika.org <oon at informatika.org>:
>
>
>      Dear All,
>
> I want to ask a question about distance calculation of two points in
> X,Y (UTM).
> Is it ok if I get the distance of two points in X,Y (UTM) only with
> distance
> calculation of cartesian coordinate (pythagoras method)?
> The error getting larger (or getting huge) if I calculate the distance
> with the
> points crossing the UTM zone. (I have tried for point with (1) different
> zone,
> I don't know what will be happened if the points over more than 1 zone??)
>
> Is it any other method to get distance calculation of cartesian
> coordinates X,Y (UTM), so the result of the calculation have accuracy
> like distance calculation
> of WGS84?
> (It's ok if the error about hundred meters)
>
> thanks for your help..
>
> --
> regards,
> Oon Arfiandwi
> Software Engineer
> Bandung, Indonesia.
>
>
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> Proj at lists.maptools.org
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