Georeferenced Images

Maps for Garmin GPS units are in vector format. Therefore, files exported from Mapwel for GPS are in the vector format too. However, raster images are often used in Mapwel as a template for automatic or manual creation of vector data. Raster image must be georeferenced (calibrated) so that vector data created on top of the image have proper real world's coordinates. Some raster image files already include georeference information like projection (a method of representing the earth's surface on a plane) and map datum (a reference from which the measurements are made). Raster images without georeference information or with information not supported by Mapwel must be manually georeferenced with calibration tool.

Mapwel supports following types of georeferenced raster images:

GeoTiff files

GeoTiff files are raster images in TIFF format with embedded georeference information like tie points, transformation matrix, projection method and parameters, ellipsoid and datum code. Mapwel supports import of GeoTiff images (main menu > Image > Import GeoTiff Calibrated Image) and automatically calibrates them with use of the georeference info.

Current version of Mapwel supports about 50% of all datums defined by GeoTiff specification, including the most frequently used WGS84, WGS72, NAD83 and NAD27. Mapwel supports following projection methods in GeoTiff files:

• Mercator

• Transverse Mercator

• Universal Transverse Mercator (UTM)

• Lambert Conic Conformal, 1 and 2 standard parallels

• Oblique Mercator and Hotine Oblique Mercator

• Oblique Stereographic

• Albers Equal Area

 

OziExplorer *.MAP files

*.MAP files are text files that contain information for georeferencing of the raster image. Link to the raster image is included in the *.MAP file. Use main menu > Image > Import OziExplorer Calibrated Image to import this raster image and georeference data into work area of Mapwel. Image is automatically georeferenced and ready to create map from.

Georeference info in a *.MAP file includes map projection, datum and 2 or more calibration points.

Current version of Mapwel supports almost all datums supported by OziExplorer and the following projections and projection methods:

• (UTM) Universal Transverse Mercator

• (ITA1) Italy Grid Zone 1

• (ITA2) Italy Grid Zone 2

• (BNG) British National Grid(IG) Irish Grid

• (SUI) Swiss Grid

• (VICGRID) Victoria Australia

• (VG94) VICGRID94 Victoria Australia

• Lambert Conformal Conic

• Mercator

• Transverse Mercator

• (I) France Zone I

• (II) France Zone II

• (III) France Zone III

• (IV) France Zone IV

• (SG) Swedish Grid

• Albers Equal Area