[Proj] Common term for geographic and projected coordinates?
EMiller at dfg.ca.gov
Wed Feb 4 14:43:46 EST 2009
>>> On 2/4/2009 at 10:37 AM, "Karney, Charles" <ckarney at Sarnoff.com>
>> From: Mikael Rittri [Mikael.Rittri at carmenta.com]
>> Date: Wednesday, February 04, 2009 05:19
>> Subject: [Proj] Common term for geographic and projected
>> I am trying to document a method that tranforms pixel
>> to either projected or geographic coordinates, depending on whether
>> the window is presented with a map projection or just as lat-lon
>> right, Pseudo Plate Carrée).
> In the vision world, the conversion for "world" coordinates to pixels
> accomplished by a "camera matrix"
> In general this is a projective map from 3d to 2d. The simple case
> you're considering is a similarity transform. The transformation
> pixel to projected coordinates is given by the inverse of the camera
I don't think that's what the op is interested in. It's just 2D to 2D
scaling and translation with some type conversion handling (int <->
double). I couldn't find a good explanation online but search for
"converting screen coordinates to map coordinates" or something similar.
The map coordinates are always some projection as the op noticed. It's
Eric G. Miller
CA Dept. of Fish & Game
More information about the Proj