Changing data from one UTM zone to another UTM zone?

Question

My situation is I am doing a project in western NY and we are under UTM 17N, but most of the data I have is in UTM 18 N because most of the state is in 18N, so the datasets I get from the state are in 18N. Now I went into ArcCatalog and changed the projection to 17N for the shapefiles, all of which is in NAD 1983. It made them the right scale, but they are about 200 miles apart, the 18N is on the west of the 17N now. How can I align these shapefiles? Should I give a higher or lower easting? if so, how is this done. or is there a tool for which this can be done?

Notes: I currently have vectors and Rasters in the map and will be transforming the vectors to raster later on when I have them overlaid correctly. I know how to georeference any raster dataset that may be incorrect. The problem right now is the vector layers. Both of the files say this below.

Projected Coordinate System: NAD_1983_UTM_Zone_17N
Projection: Transverse_Mercator
false_easting: 500000.00000000
false_northing: 0.00000000
central_meridian: -81.00000000
scale_factor: 0.99960000
latitude_of_origin: 0.00000000
Linear Unit:  Meter

RobertBorchert · Answer

Dump UTM and create a new GeoDatabase and convert everything to State Plane  New York West.  Try to find a map that shows you the coverage of State Plane New York and determine IF Your entire area that you a concerned about fit  into it.

If you create the new GDB in the desired projection and you import your features it should convert them to State Plane as you load.

My situation is I am doing a project in western NY and we are under UTM 17N, but most of the data I have is in UTM 18 N because most of the state is in 18N, so the datasets I get from the state are in 18N. Now I went into ArcCatalog and changed the projection to 17N for the shapefiles, all of which is in NAD 1983. It made them the right scale, but they are about 200 miles apart, the 18N is on the west of the 17N now. How can I align these shapefiles? Should I give a higher or lower easting? if so, how is this done. or is there a tool for which this can be done?

Notes: I currently have vectors and Rasters in the map and will be transforming the vectors to raster later on when I have them overlaid correctly. I know how to georeference any raster dataset that may be incorrect. The problem right now is the vector layers. Both of the files say this below.

Projected Coordinate System: NAD_1983_UTM_Zone_17N
Projection: Transverse_Mercator
false_easting: 500000.00000000
false_northing: 0.00000000
central_meridian: -81.00000000
scale_factor: 0.99960000
latitude_of_origin: 0.00000000
Linear Unit:  Meter

curtvprice · Answer

If you used the Define Projection tool, or modified the coordinate system properties in a dialog box, that does not change the coordinates, it just changes the metadata that tells ArcGIS what projection the coordinates reference. So for those shapefiles that you altered, the coordinates are still in the original projection, but ArcGIS thinks they are in the new UTM zone so draws them in the wrong place.

You need to project the datasets from 18N to 17N using the Project tool.

Hope this helps.

Update: Hi Mark - you responded a few seconds before I did!

markdenil · Answer

You should Project the data from zone 18 to 17.
It sounds, from both what you report you did, and from the results,
like you just changed the definition on the feature class to zone 17.
That would be the source of your problem.

The eastings are the same for each zone; in fact, everything is the same except the central meridian.
(except perhaps the northing, for northern or southern hemisphere).
But different zones are different projections: so you project to get from one to another.