EPSG code for...

[Dean Mikkelsen]

Hi again,

MTM is defined for Canada. They are 3 degree Modified Transverse Mercator projections. They will not apply to Canada.

For a reference see the following web-sites:

MTM:
http://www.geod.nrcan.gc.ca/images/products/MTM.jpg

UTM:
http://www.geod.nrcan.gc.ca/images/products/UTM.jpg

Both were referred to via:
http://www.geod.nrcan.gc.ca/index_e/online_apps_e/appNtv2_e/appntv2_utm_e.html

Cheers,
Dean



----- Original Message -----
From: "Christopher R. Thorne" <christhorne at SYMPATICO.CA>
Date: Tuesday, June 14, 2005 7:36 am
Subject: Re: [UMN_MAPSERVER-USERS] EPSG code for...

> Hello me again,
> I finally tracked down the metadata for the data that was given to 
> me 
> with the strange projection. Well it gets stranger. Here is what I 
> found. I have two shape files of the Los Angeles county
> 
> 1st shape file :
> ----------------
> Datum:NAD27
> Units: Meters
> Ellipsoid:Clark 1866
> Projection: UTM, Zone 11
> 
>  * Possible EPSG codes found:
> 
> # NAD27(76) / MTM zone 11
> <2020> +proj=tmerc +lat_0=0 +lon_0=-82.5 +k=0.999900 +x_0=304800 
> +y_0=0 
> +ellps=clrk66 +units=m +no_defs  no_defs <>
> 
> # NAD27 / UTM zone 11N
> <26711> +proj=utm +zone=11 +ellps=clrk66 +datum=NAD27 +units=m 
> +no_defs 
>  no_defs <>
> 
> 2nd shape file:
> 
> Datum:NAD83
> Units: Meters
> Ellipsoid:Clark 1866
> Projection: UTM, Zone 11
> 
>   * Possible EPSG Codes found:
> 
>   NONE FOUND.....
> 
> This makes me think that NAD83 with a Clark 1866 Ellipsoid is not 
> a 
> valid projection. Am I on the right trake of thinking or is there 
> actually an EPSG code with:
> 
> <????> +proj=utm +zone=11 +ellps=clrk66 +datum=NAD83 +units=m 
> +no_defs 
> no_defs <>
> 
> Comments?
> Chris
> 
> Christopher R. Thorne wrote:
> > Hello Dean,
> > 
> > Dean C. Mikkelsen wrote:
> > 
> >> Hi Chris,
> >>
> >> Take a look at the following web-page.
> >> I am leaning towards a problem now in defining which State Plane
> >> Co-ordinate System is being used. i.e. one of the ones we are 
> using is
> >> wrong - we may actually be north or south of the current one. 
> Now the
> >> trick is to determine which one. A note to other readers 
> epsg:4326 is
> >> WGS84.
> >>
> >> Did you try reprojecting the NAD27 Layer with the NAD83 
> definition? 
> > 
> > 
> > Yes I did that and the layers switched positions.
> > 
> > Or
> > 
> >> with epsg:4326? What happens?
> >>
> > with setting the projection to the lat/long layers, they are not 
> found 
> > in outer space, not within the world extent.
> > 
> >> http://www.wadetrim.com/resources/articles/sblocks.htm
> > 
> > 
> > Thanks for the good reference. The reason why I got into this 
> situation 
> > was because I am four steps removed from the data provider. I 
> only 
> > managed to get the information that you already know and I was 
> hoping 
> > the information was correct. The other problem was that I was 
> not sure 
> > how to identify the issues, confidently. If not I will 
> definitely push 
> > for more information.
> > 
> > Cheers and thanks again,
> > Chris
> > 
> 
> 
> -- 
> Christopher R. Thorne, GIS Specialist
> -
> christhorne at sympatico.ca
> Tel:(613)523-6593, Ottawa ON Canada
> -----------------------------
>