Importing Dxf Files (Autocad®) - GPS TrackMaker Reference Manual

2.7 Importing DRG Images
This option is available only in GPS TrackMaker Professional®.
Digital Raster Graphics (DRG) are raster images with an extra text file where are registered the parameters of
calibration. Usually DRG are paper charts that were scanned and georeferenced. The most of available DRG files
are topographic charts from U.S. Geological Survey (USGS) , georeferenced in the UTM system.
To open a DRG file, click in File > Open File and choose the following options:
•
Geocoded Tagged Image (TIF and TFW)
• Geocoded JPEG Image (JPG and JGW)
• Geocoded GIF Image (GIF and GFW)
• Geocoded BMP Image (BMP and BPW)
The text files used to calibrate the image (TFW, JGW, etc) don't possess information about the datum and the
rectangular zone. When a DRG is imported, it is necessary to indicate the correct datum and the zone of the
image.
TIP: Usually zone and datum are indicated close to the map legends.
Special Case of TIFF files
DRG files in TIFF format may have in the image file the complete data for calibration. So, the use of the TFW file is
not necessary. These files are called GeoTiff and are opened by GTM PRO®. For further information, see the topic
Importing GeoTiff Files.
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