Can I change projection from WGS84 to EPSG3857??

[Shahar]

Hello,

 

I was wondering if I can convert the coordinate system of a layer from WGS84 to the OpenStreetMap projection - Mercator EPSG3857??

I didn't find it in the .prj file.

Can it be done and if so, how?

 

Thank you,

 

Shahar

[Uffe Kousgaard]

Hi,

It is listed in 11.0 like this:
"Popular Visualization CRS\p3857", 10, 157, 7, 0

Maybe you have an older version of MI.

Btw: OpenStreetMap uses wgs84 as native coordinates in the master
database, but may be using EPSG 3857 (same as Google uses) when
rendering for the website through mapnik.

Regards
Uffe Kousgaard

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[Shahar]

So if I have MI 10.5 I can't do it?

There is no other way?

 

Shahar

[Greg]

I think you should be able to add it as a custom projection as the datum (157 = Popular Visualization CRS / Mercator) is listed in the MI v10.5 user guide (appendix B - worth a look!). To see how to add it to the MapInfow.prj file, look at this link:

http://www.kxcad.net/mapinfo/mapinfo_professional/mapinfow-21-19.html 

HTH

Greg.

[Uffe Kousgaard]

Hi,

Version 10.5 has the same line in the PRJ file. And 10.0. But not 9.5.

Regards
Uffe Kousgaard


Shahar wrote:

--

[Tony Pilkington]

Shahar

 

MI does have a Sphere in its repertoire; it's ellipsoid number 12 and is the sphere on which all MI Spherical calculations are done (sphericaldistance, sphericalarea, sphericalobjectlen) irrespective of actual datum.

 

To set up a lat/long projection, called Ball, place the following line in the .prj file:

 

1,999,12,0,0,0

You should end up with a line like this when you select the projection

"Longitude / Latitude (Ball)", 1, 999,12,0,0 0

 

and for Mercator

 

10,999,12,0,0,0,"m"

You should end up with a line like this when you select the projection

"Mercator (Ball)", 10, 999, 12, 0., 0., 0.,7,0

 

The Google Sphere has a axis value of 6378137 and the MI Sphere 6370997, ie a ratio of 0.99888; quite close to 1...

 

This may be close enough for a display purposes. For measurement purposes using spherical functions it will be exactly the same as MI would indicate.

 

This is also the projection used in the production of a lot of orthorectified imagery.

 

Tony

 

 

 

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