Monthly Archives: September 2012

DNRGPS tutorial – GIS data in Michigan GeoRef to GPS

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1) Launch ArcMap and add your data in Michigan GeoRef coordinates to your map.

2) Make ArcToolbox visible and expand Data Management Tools > Projections and Transformations > Feature > and double-click the Project tool to open it. You can also open the Search window (Windows > Search or Ctrl-F) and search for the Project (Data Management) tool.

3) Select the layer you want on your GPS as the Input Dataset and verify that the Input Coordinate System is NAD_1983_Michigan_GeoRef_Meters. Choose the location and name of your output file (maybe adding WGS84 to the end of the file name). Be sure you are saving a shapefile and not a geodatabase feature class. Click the Spatial Reference Properties icon to select the Output Coordinate System. Expand Geographic Coordinate Systems, then World, and select WGS 1984.
Tip: If you right-click on this (or any) projection definition and choose “Add to Favorites” it will be easier to find in the future.

4) Click OK to run the tool. Your re-projected layer will be added to your map after the tool has finished. You can verify your new layer’s projection by opening its properties and examining the Source tab. If all went well, the Projected Coordinate System should read GCS_WGS_1984.

5) Launch DNRGPS. Choose File > Load From > File… and navigate to the shapefile you just saved. Select it and click Open. Verify that the values in Latitude and y_proj are the same, that Longitude and x_proj are the same, and Projection: No Projection is shown at the bottom of the window. If the values are different or a projection name is shown, something was not set properly in a earlier step and DNR GPS is converting projected to unprojected coordinates, perhaps incorrectly…

6) Connect your GPS and turn it on. You should see a message near the top of the window that your GPS now connected. If you don’t, verify the GPS is on, check your cable, and select GPS > Connect to Default GPS. If that fails, try GPS > Find GPS.

7) To transfer your GPS data, select Waypoint > Upload. Your points should appear in the DNR GPS window. (if you loaded a line shapefile into DNR GPS, choose Track > Upload). You should see a status message after the upload is complete.

DNR GPS tutorial – GPS data to Michigan Georef in ArcGIS

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1) Launch DNR GPS and ensure the projection is set to None (File > Set Projection and click the Set Projection to NONE button:

 

 

2) Connect your GPS and turn it on. You should see a message near the top of the window that your GPS now connected. If you don’t, verify the GPS is on, check your cable, and select GPS > Connect to Default GPS. If that fails, try GPS > Find GPS.

3) To transfer your GPS data, select Waypoint > Download. Your points should appear in the DNR GPS window.

4) To save your GPS data, choose File > Save To > File… and Save as type… text file (comma delimited) (*.txt). Consider this file your ‘backup’ that can be easily opened by DNR GPS without issue. Next, choose File > Save To > File… and Save as type: ESRI Shapefile (*.shp). This file can be manipulated in your GIS software.

5) Launch ArcMap and add the shapefile you just saved in step 4 to your map.

6) Make ArcToolbox visible and expand Data Management Tools > Projections and Transformations > Feature > and double-click the Project tool to open it. You can also open the Search window (Windows > Search or Ctrl-F) and search for the Project (Data Management) tool.

7) Add your shapefile as the Input Dataset and verify that the Input Coordinate System is GCS_WGS_1984. Choose the location and name of your output file (maybe adding MGRF to the end of the file name). Click the Spatial Reference Properties icon to select the Output Coordinate System. Expand Projected Coordinate Systems, then State Systems, and select NAD 1983 Michigan GeoRef (Meters).

Tip: If you right-click on this (or any) projection definition and choose “Add to Favorites” it will be easier to find in the future.

8) Click OK to run the tool. Your re-projected layer will be added to your map after the tool has finished. You can verify its projection by opening the layer’s properties and examining the Source tab. If all went well, the Projected Coordinate System should read NAD_1983_Michigan_GeoRef_Meters.

DNRGPS and Michigan GeoRef coordinates

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DNRGPS, the new replacement for DNRGarmin, does not handle the Michigan Georef projection properly. If you load an existing shapefile in Michigan Georef coordinates into DNRGPS, the latitude and longitude values are changed to the wrong part of the Earth (About 25 degrees of latitude is added and longitude is changed from ~ -88 to 175 degrees: a change of almost 265 degrees). Similarly, if data is transferred from your GPS to DNRGPS and the Michigan GeoRef projection is then applied, the latitude and longitude values stay correct, but the projected coordinates (used by ArcGIS or other GIS software) are changed so the data are on the wrong side of the Earth.

To avoid problems with your data ending up in the wrong hemisphere, do the following:

 

1) If transferring data from your GPS to GIS software, use either unprojected (“no projection” in DNRGPS, which = WGS84 lat/lon) coordinates or the appropriate UTM zone for your part of Michigan (zone 15N in the extreme western UP, zone 16N for most of the UP and the western 2/3 of the LP , or zone 17N in the extreme eastern UP and the eastern 1/3 of the LP). See figure 1 for UTM zones in Michigan.

 

Figure 1 - MI UTM zones
Figure 1 – UTM zones in Michigan (click for a larger version)

 

If you need your spatial data to be in Michigan GeoRef coordinates, use the Project tool in ArcGIS (or the reproject function in your GIS software if you are using another package) to convert your data to Michigan GeoRef coordinates.

 

2) If you are transferring data in GIS format (shapefile or geodatabase) to your GPS and it is in Michigan GeoRef coordinates, you should first reproject it to either Geographic coordinates or to the appropriate UTM zone.

I have filed a bug report with the developers of DNRGPS, but they have more than a hundred other issues to fix so it may be a while before this is resolved. Fortunately, this is a non-fatal error and can be avoided with some planning.

DNRGPS updated

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DNRGPS 6.0.0.15 was released recently. This version fixes a couple of major bugs. See the release notes for details.

Tip: this software does not, at present, handle the Michigan GeoRef projection properly. I have filed a bug report to the developers, but saving files in either unprojected lat/lon or UTM and converting in ArcGIS to Michigan GeoRef is the best solution until this problem is fixed.

ArcGIS application errors – some troubleshooting tips

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Twice today I’ve seen problems with ArcGIS 10 (and 10.1) failing to launch. In one instance, no specific application error was given – ArcMap just failed to start with a ‘serious error’ dialog, and in the other, some direction was provided by ArcMap in the form of an error message.

In both cases, the user had a corrupt default user geodatabase. The location of the default geodatabase may be given in the error message. If not, it should be located in <user profile>\My Documents\ArcGIS. If you are working on a lab machine, the location will be h:\ArcGIS\  The file is named Default.gdb, and if ArcMap has had trouble loading more than once, you may have multiple copies named Default.gdb, Default.gdb1, Default.gdb2…

The ESRI knowledge base article 38523 suggests several fixes, the most important of which seems to be deleting any Default.gdb files in the users profile directory. I found that using Windows worked properly, as ArcCatalog seems unable to remove the offending files. One machine I worked on today had more than 150 default.gdb files (all of which were corrupt and preventing ArcMap from launching).