Latest Contributions by MelitaKennedy

‎10-23-2012

This may be what you're confused about... When part of a UTM-related coordinate system name, 'S' means South and 'N' means North for the Southern and Northern hemisphere zones. If given a UTM string or notation like 17S 432938 3868920, the 'S' could mean a latitude band. That is, the data falls between 32N and 40N. Melita

‎10-19-2012

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

‎10-19-2012

Hi Sarina, Yes, you need to apply a transformation. This is complicated by the fact that you probably do not have the file installed for the 'best' transformation for Canada. First you'll need to download the grid file, Ntv2_0.gsb, from NRCanada. Once you have it, browse to your ArcGIS installation folder and look for pedata. In pedata, go to ntv2. If there's a canada folder, copy Ntv2_0.gsb there. If there isn't, create a folder called canada and then copy the file there. At this point, you'll need to restart ArcGIS if you haven't closed it already. Now when you change the data frame's coordinate system, click the Transformations button, and choose NAD_1927_To_NAD_1983_NTv2_Canada. Or use the Project Tool. In 10.1, if the grid file isn't there, the transformation won't even be listed. That's a change from 10.0 and earlier, where the transformation would be listed, but wouldn't actually do anything because the underlaying grid wasn't there. Melita

‎10-16-2012

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

‎10-16-2012

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

‎10-16-2012

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

‎10-16-2012

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

‎10-16-2012

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

‎10-15-2012

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

‎10-15-2012

Please see my answer to your other post. Melita

‎10-15-2012

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

‎10-12-2012

Hi Greg, You're creating a datum, not a geographic coordinate system. Try using 4326 rather than 6326! geographic coordinate system: name, datum (spheroid), prime meridian, angular unit Melita

‎10-12-2012

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

‎10-08-2012

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

‎10-05-2012

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

My Ideas

Latest Contributions by MelitaKennedy

Re: WGS_1984_UTM_Zone_17S to UTM Zone 17, Southern Hemisphere - Raster file

Re: Grid lines stay 'straight' instead of curving with the projection

Re: Projection - NAD27 to Nad83 Zone 13N

Re: Problems Creating Projection File

Re: Problems Creating Projection File

Re: Problems Creating Projection File

Re: Problems Creating Projection File

Re: Problems Creating Projection File

Re: Longitude Latitude to British National Grid XY PROBLEMS GALORE

Re: UTM coordinates question

Re: OS Land-Form PANORAMA Projection

Re: Plug-in Data Source - Geographic Coordinate System

Re: GCS_WGS_1984 Coordinate system

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