[postgis-users] Projection question

[Ehud Shabtai]

On 8/9/05, Markus Schaber <schabi at logix-tt.com> wrote:

> > As I have data from all around the world, is there a single projection
> > which would preserve the distance for every location?
> 
> Sadly, there is none, as it is geometrically impossible to project a
> spherical object into a plain one without loss.

I don't mind losing the angles or using a projection which looks bad,
but is there any projection which can only preserve the distance
(maybe except some parts on the edges of earth) on the expense of the
angles?

> Maybe the best idea is to use a group of zone projections that cover the
> whole planet (e. G. UTM) and then write a plpgsql function that maps a
> geometry to the appropriate zone srid. This would allow you to write
> something like:
> 
> transform(buffer(transform(the_geom, find_utm_srid(the_geom)), 100, 4326);'

Thanks for the idea,

Ehud.