[gdal-dev] geographic vs projected coordinate system

[Andre Joost]

Am 10.06.2013 08:37, schrieb adi_khan:
> Hi all,
> I am a novice to geospatialrelated terminology...and going through some
> literature to understand better..
> Could someone please tell difference btwn geographic and projected
> coordinate system...
> I mean, I am not able to imagine how I can  see an (satellite) image on
> screen ( flat surface) and say it is in geographic cordinate system (GCS)...
> as GCS means lat/long and I see it on a flat screen, so should it not be
> projected if I am seeing it on a flat screen? And if it is projected, then
> how can it be in GCS ?
>

What you see on the screen, is in fact projected, but with a simple one 
degree = one unit on the screen projection. The extent of that map is 
still +/- 180°/90°

This "projection" has none of the benefits usual projection have, like 
true areas, true angles or true lenghts.

HTH,
André Joost