Plate Carre with latitude shift

[Espen Isaksen]

To further discuss this topic. I created a map of Europe in a regular
EPSG:32662(proj=eqc) and one map of Europe with a latitude shift to 60
degrees north:

Map of Europe in 32662:
http://bildr.no/view/143324

Map of Europe with latitude shift:
http://bildr.no/view/143325

The latter is close to what I want. However, if I move my zoom in to
some part of the nordic countries, the decimal degree coordinates will
no longer correspond with my coordinates in my 32662 projection with
the latitude shift. Why is this?

Espen


On 16/01/2008, Espen Isaksen <espen.isaksen at gmail.com> wrote:
>  > EPSG:4326 is a geographic coordinate system, and the coordinates are in
> > decimal degrees.  +proj=eqc is a projected coordinate system and the
> > coordinates are meters.  The location (-180,90) would be roughly
> > (-20000000,100000).
> >
> > Essentially eqc (ie. equidistant cylindrical or Plate Carree) is just
> > a rescaling of EPSG:4326 from degrees to meters.
> >
>
> Ok I understand this.
>
> > I'm afraid I just don't get what you hope to accomplish with +lat_ts=60.
> > Are you hoping to get one projected meter being one meter on the ground
> > at 60N as opposed to it being one meter at the equator as is the default?
> > I'm not aware of proj=eqc supporting any such option.
>
> Yes I am trying to change the projection such that it gets less
> distorted in areas near the north pole. I tried to set the mapfile
> like this:
>
> EXTENT 593674.73 6669772.29 594581.49 6670417.57
> PROJECTION
>      "+proj=eqc +lat_ts=60 +lon_0=0 +x_0=0 +y_0=0 +ellps=WGS84
> +datum=WGS84 +no_defs +units=m"
> END
>
> which seems to create an quite ok map. Much better than setting
> +lat_ts=0. Although I do not understand why Mapserver creates a map
> over a different area than what my original decimal degree areas
> indicates(I used proj to convert them)?
>
> By the way my original decimal degree coordinates are:
> 10.6661 59.9155 10.6824 59.9213
>
> Perhaps what I am doing is just nonsense...
>
> Espen
>