[OSM-talk] JOSM and scale

Tue Mar 25 18:21:10 GMT 2008

> In Mercator distance is constant independent of orientation, isn't it?

I don't know what you mean exactly.

If you use JOSM with the Mercator projection and draw a perfect circle in the North of Sweden, you are actually drawing a horizontal ellipse (east-west oriented) in the real world.

Lucas

Juan Lucas Domínguez Rubio
Prodevelop SL, Valencia (España)
Tlf.: 96.351.06.12 -- Fax: 96.351.09.68
http://www.prodevelop.es <http://www.prodevelop.es/> 

________________________________

De: talk-bounces at openstreetmap.org en nombre de David Earl
Enviado el: mar 25/03/2008 18:30
Para: Andy Robinson (blackadder)
CC: talk at openstreetmap.org
Asunto: Re: [OSM-talk] JOSM and scale

On 25/03/2008 17:16, Andy Robinson (blackadder) wrote:
> Vector editing software such as CAD packages are normally scale free at the
> editing level. The co-ordinates are simply sufficient, especially if you
> have the ability to draw a vector a specific distance from a point as a
> polar ray or snapped relative to something else. Its only at plot time do
> you decide what scale you wish to make your view. Perhaps if JOSM worked the
> same way there would really be no need for a scale bar, especially when the
> scale bar needs to read differently for vertical and horizontal projection
> distances.

I disagree. I often dictate 'postbox 10m after junction' or '... set
back 30m from road' by my estimate, and I need to see what that amounts
to in JOSM - though apparently I have been misled so far! Which would
explain why my estimates haven't seemed to correspond to reality sometimes.

In Mercator distance is constant independent of orientation, isn't it?

David

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