From GpsWiki
Using Third Party Imagery
In addition to the Delorme data that may be downloaded from Netlink, the PN-series GPS units are capable of loading imagery from other sources. This requires Delorme XMap GIS software. All products in the XMap line are equivalently capable of loading third party imagery - XMap Professional is the cheapest and has historically been offered to PN-series owners at an unadvertised discount when ordering from Delorme by phone.
How to Load Third-Party Imagery
- Georeferenced Data
Many sources of free aerial imagery are already georeferenced. Common formats accepted by XMap include GeoTIFFs(.tif or .tiff) and most MrSIDs(.sid). These files may be loaded into XMap from the Map Data tab. Click on the Data button and click add, then select your GeoTIFF or MrSID file(s).
- Unreferenced Data
Some aerial imagery and many useful maps are available only in unreferenced image formats like jpeg. These files are loaded through the ImageReg tab. Click on Load Image to load the image into XMap and follow the directions that appear. A common format used for maps that is not directly supported by XMap is PDF. Such maps may be converted into formats readable by XMap by opening them in an image editor and saving them in an appropriate format. The GIMP is one free program that can do this.
Free Sources of Third-Party Imagery
There are several sources of free imagery, including the following:
- http://seamless.usgs.gov
- http://datagateway.nrcs.usda.gov/
- http://www.src.com/datasets/datasets_aerial.html
- http://edc2.usgs.gov/geodata/index.php
- http://www.holoscenes.com/special/drg_sources.html
- http://libremap.org/data/
- Arizona
- California GIS, DRG, DOQQ, and Landsat
- Maryland
- Massachusetts GIS
- Minnesota
- New Jersey Geographic Information Network
- New York State GIS Clearinghouse
- Ohio Statewide Imagery Program
- Oregon
- Pennsylvania
- http://www.lib.utexas.edu/maps
While they provide more options than are available over Netlink, they can be more difficult to use and less reliable.
Using a Paper Map
Another option is to take a paper map and digitally scan it, then use XMap's ImageReg tab to georeference it. There are basically two options to scanning a paper map:
- Cut it up into 8x11 pieces for scanning on a personal flatbed scanner, and then using a photo editor to re-assemble the pieces, or
- Take it down to Kinko's and let them scan it on their 36" wide scanner.
Believe me, option 2 is the way to go!
Using PDF Files
Saving a PDF file as an image file (.jpg, .bmp, etc) will work also. This is a great way to get a park map onto the PN-40.
- Save the PDF file and then use XMap's ImageReg tab to georeference it.
