Latest Contributions by MelitaKennedy

Hi, For performance reasons, we do not densify (or generalize) lines when they're re-projected. Try densifying the data. There's a densify tool in the Editing toolbox. Melita ... View more

I don't know. I believe the metadata's correct for the CAD software, so someone working with it in that software would need to know that information. Because the data was georeferenced to a 'known' coordinate system, it just works in the GIS software. Melita ... View more

Okay, I downloaded the DWG. Ignore everything I said and what the metadata says. Just assign the NAD 1983 10TM AEP Resource prj to the data. A quick way to check it is to add the AltaLIS data to ArcMap. You should get a 'missing coordinate system' message; ignore it. Add some reference data. Set the data frame's coordinate system to the AEP Resource coordinate system. The reference data, as long as it has a coordinate system, will get projected on-the-fly and should line up. Melita ... View more

Can you post the data's current extents (using this coordinate system), plus a general idea of where it should be located? Thanks, Melita ... View more

Hi, Try changing the false northing to -5000000. Melita ... View more

Hi, I see a few possibilities. Canadian data, right? The information doesn't match any of our existing 10TM definitions, unfortunately. First, change the central meridian to -115. (115W). Also I would try changing the latitude of origin to zero. I think geographic location just identifies the area of the data, and may not have anything to do with the projection parameters. With the latitude of origin set to the equator, Y values will be around 5-6 million. However, with a -5000000 m false northing, that will reduce the size of the Y values. Lastly, change the scale factor to 1.0. Scale factor is applied as a multiplier to the numbers coming out of the algorithm, before the false easting and false northing values are added. Melita ... View more

If the lat/lon coordinates really are in WGS84, you need to set a geographic/datum transformation to convert between WGS84 and OSGB36. The best solution is to follow Jim Sibbald's instructions here which has you download a file from OS, and set up some files on your computer to properly use it. If you have 10.1, you only need to download the file, and place it in your ArcGIS installation, pedata\ntv2\uk folder. A faster solution to see if the problem is datum transformation-related is to try to set OSGB_1936_To_WGS_1984_7PAR. The points may still be off a bit, but should be better than 30m. Melita ... View more

Please see my answer to your other post. Melita ... View more

I think you just need to define the coordinate system ("Define Projection" tool). Use "British National Grid." ... View more

When a data frame in ArcMap is using a geographic coordinate system, an internal projection occurs. It's very simple--the latitude and longitude values are treated as if they're linear and simply displayed. This is sometimes called a pseudo-Plate Carree projection. A true Plate Carree projection would convert the latitude and longitude values to radians and scale them by radius of the earth model in use. Many people would say that you shouldn't make a map (particularly a printed one) using a geographic coordinate system. Instead you should pick an appropriate projected coordinate system based on the purpose of the map and its extent. Melita ... View more

Hello, If you already have a .prj file, add it to your Favorites location: On XP, C:\Documents and Settings\login\Application Data\ESRI\Desktop10.1\ArcMap\Coordinate Systems On Win7: C:\Users\login\AppData\Roaming\ESRI\Desktop10.1\ArcMap\ Coordinate Systems If you want to create a new coordinate system, click the globe icon at top right (to the left of the star icon). To modify an existing coordinate system, right click it in the directory listing and choose "Copy and Modify". If you want to modify a .prj file in Notepad or some other editing tool, you'll have to add it to Favorites first which will write the definition to a file. Melita ... View more

Hi Troy, When I poke around, 2944 is listed as the build number for 10.1 prerelease for Desktop, Server, Engine, and Reader. Melita ... View more

In 102100 and 3857, we can use an ellipsoid/spheroid-based geographic coordinate system because the map projection algorithm is handling the conversion to a sphere internally. 102100: PROJECTION["Mercator_Auxiliary_Sphere"] 102113: PROJECTION["Mercator"] This parameter: PARAMETER["Auxiliary_Sphere_Type",0.0] determines how an ellipsoid-based GCS should be handled in a map projection that supports spheres only. The zero value means to use the semimajor axis for the sphere's radius. "1": use semiminor axis, "2": calculate authalic sphere's radius, "3": calculate authalic sphere's radius and convert geodetic latitudes to authalic latitudes. With 102113 (3785), because the GCS was sphere-based, technically you would have to do a geographic (datum) transformation from WGS 1984 to the sphere-based GCS before the projection could occur. This is more difficult to handle because it means all data has to go through a geographic transformation. In 102100 (3857) only non-WGS84 data has to go through a geographic transformation. Both definitions give exactly the same results. Melita (edited to add sentence about results, 1:22pm PDT) ... View more