GPSy™ supports the use of user-scanned maps; calibrated GeoTIFF images (such as those on the USGS topo map CD-ROMs); Japan National Map Center Digital Maps; as well as TIFF+TFW and JPEG+JPW calibrated images. Once maps are calibrated, you can download and overlay track and waypoint data; view your position in real-time or from a track log; or upload waypoints using our new "Click and load" waypoint uploading.
See the following link for sources of GeoTIFF format maps, including USGS DRG Topo Maps and Digital Orthophoto Maps:
http://www.gpsy.com/maps/
Scanned map support requires QuickTime 3 to be installed. The latest version of QT is 3.02 as of 8/20/98, we highly recommend that it be installed as it fixes a GeoTIFF related issue:
http://quicktime.apple.com
GeoTIFF Images
GPSy supports GeoTIFF tagged USGS CD-ROM Digital Raster Graphs (aka USGS Topo maps on CD-ROM). GPSy will recognize the GeoTIFF tags and auto-calibrate the map. Be sure to match your primary display datum to the one that the map uses (usually located on in the map README or border of the map).
For a list of CD-ROMs available in GeoTIFF format, see: http://www.gpsy.com/maps/
If you come across any GeoTIFF images that open with "Unrecognized GeoTIFF Tags" in GPSy, please contact technical support <support@gpsy.com>.
TIFF Images + TFW (JPEG+JPW) Calibration Files
GPSy supports TIFF images with ArcView style TFW (TIFF World) and JPW (JPEG World) calibration files. These can be found on various topographic maps and data sample sets from commercial vendors. However, the world file specfication is incomplete as provided by most vendors since it does not include the UTM zone of the map, which is required with a global GIS package such as GPSy. Please read the FAQ on how to modify these files to include the zone number:
http://www.gpsy.com/faq/maps.html#tfw
Calibrating user scanned maps
GPSy can handle map images that you scan in yourself. Please follow these directions:
1) First, obtain a scanned map somewhere. Many users have successfuly scanned in atlases and maps with consumer flatbed scanners. With QuickTime 3.0 installed, GPSy supports the following file formats natively:
• GeoTIFF
• PICT
• TIFF
• JPEG
• GIF
• Sun, SGI, Photoshop
We recommend 256-color, LZW or RLE compressed TIFF files as the most efficient and fast format.
GPSy currently uses a one degree polynomial for its geomapping correlations. That means that GPSy works best with maps that have relatively straight latitude and longitude lines. Universal Transverse Mercator and Transverse Mercator maps such as those produced by the USGS tend to work well. A future release of GPSy will use higher degree polynomials.
2) Locate three known points on the map. Write down their latitudes and longitudes. The three points should not lie in a line and should look as much like an isoceles triangle as possible.
3) Open the scanned map in GPSy using the "Open Map" command.
4) GPSy should open the file required. If the file is large and GPSy's memory allocation is small, then this may can up to a minute or two to open.
5) The map is zoomable and scrollable. To zoom in, hold down the Apple key and use the '-' and '+' keys to zoom in and out. The scroll bars should work as in other Macintosh applications. You can alternatively scroll using the arrow keys or by holding down the space key to drag and scroll.
6) To calibrate the map, hold down the option key while clicking on the three known points (in step #2). Enter in the coordinates in the panel that comes up.
7) After the three points have been entered, the map should now work as a calibrated map. You current GPS location should be indicated by a red + icon inside a "bullseye". The blue vector inside the bullseye represents your current heading. The green circle on the outer edge of the bullseye is the bearing to the next waypoint -- if your GPS unit is supplying this data.
8) Be sure to save your calibrations. Select "save" from the File menu. Save the file with a separate name as your image file. Your calibration file will contain a pointer back to the original image file, so if you open the calibration file, it'll automatically open the image file. This is handy when the image file is on a read-only media such as a CD-ROM or DVD.
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Notes on scanned images:
1) GPSy attempts to use temporary system memory for map files before switching to using application memory. This allows the memory footprint of the basic GPSy application to remain small. Turn off virtual memory or RamDoubler and free up memory by quitting as many applications as possible before launching GPSy and opening large map files.
2) If GPSy has less memory than needed to open the full version of the image file, then it will derez the image in order to make it fit in the memory available. This means that if you don't have enough memory, you'll be presented with a lower resolution image than the original file. Decreasing your color depth in your Monitor control panel will increase the display speed of the file. Note that most USGS DRGs are in 256 color GeoTIFFs anyway, so setting your monitor to anything higher only wastes memory.
3) GPSy's native file support is extremely fast when scrolling, with the payoff of a larger memory footprint. However, you can change the footprint in #2 as noted, with the payoff of lower resolution. It is impossible to have all three at the same time: 1) fast scrolling; 2) low memory requirements; and 3) fast file opens. Please send comments if you disagree with the tradeoff made in GPSy.
In comparison, note that while GPSy only needs 1 megabyte + the uncompressed memory size of an image (derezable to conserve memory); applications such as PhotoShop require three times the full memory size of an image, at least (although Photoshop has a virtual memory scheme that's slow).
4) GPSy's one-degree map polynomial algorithm works best with small-scale maps such as a city or state, rather than an entire nation or continent. We'll be moving to a higher degree polynomial in future versions of GPSy.
5) NOAA/BSB map support provided in GPSy Pro, our high-end GPS product for the Macintosh. Please inquire at <gpsy-pro-info@gpsy.com>
Please note that IN NO EVENT SHALL SOFTWARE AUTHOR BE LIABLE TO USER FOR ANY SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGE, INCLUDING, BUT NOT LIMITED TO, LOSS OF REVENUE AND LOSS OF PROFITS, OR LOSS OF LIFE OR PROPERTY, EVEN IF AUTHOR HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. In other words, don't use GPSy for mission , life-critical, or plain stupid purposes (e.g., flying blind at night with only a GPS unit and GPSy to guide you; delivering pizzas in a bad neighborhood; driving while looking at a laptop) unless you are willing to acknowledge that it may produce miscalculations or results with unforeseen or grave consequences.
This product is not provided as either a primary or professional navigation aid and should not be used as such. Liability arising from the use of this product is limited to the purchase price of this product.
