GPSMap Edit - Frequently Asked Questions

    General questions

  1. Who needs the software?
    GPSMap Edit is designed to help owners of Garmin GPS receivers to create own maps. The software allows to quick loading and viewing vector maps in so-called "Polish format", comparing them with different geodetic data like raster maps, GPS tracks and waypoints, and editing the mаps.

    Recently, the export to format ALAN Map 500 MapShow was implemented.

    In addition, the software may be used for converting GPS-tracks and waypoints among various formats.

  2. What is "Polish format"?
    GPS navigators developed by Garmin support closed undocumented map format IMG.
    However, there is command line utility cGPSMapper.exe allowing to convert geodetic data presented in text files in open and well documented format into Garmin IMG. Its input language is called "Polish format".

  3. Where can I find maps in Polish format? Is there else software supporting this format?
    Currently there are no open sources of such maps. However, there are some converters to Polish format from other formats.

    In Russia, for instance, the convertor cMap.exe is widely used. It gets maps in GEM/GCT format from Ingit (St.Peterburg). Such maps cover mainly Russian territory.

    pGPSmap is example of software making some post-processing of Polish files. This utiliy splits map to few parts and diminishes number of points in polygons up to 255, as required by obsolete versions of cGPSMapper.exe.

    In addition, full version of cGPSMapper.exe supports shapefiles (ArcView GIS).

    And, of course, you may write you own software based on Polish format! In this case, GPSMap Edit may be used as your covertor's output verification tool and as source of ready code or parser.

  4. Is it possible to convert maps from OziExplorer MAP format?
    The maps accepted by OziExplorer are raster ones being scanned images of paper maps. Automatic recognition of such images necessory to transform the data to vector presentation is rather complex task (like OCR and even more). Some so-called vectorizer tools are available in market, but most of them have very high prices while still require large amount of manual labour.

    However, you may use raster maps in GPSMap Edit as base for manual drawing of vector ones over them, both and to fix existing vector maps.

  5. What else formats are supported by GPSMap Edit?
    GPSMap Edit supports loading of any number of maps, tracks and waypoints in OziExplorer format (MAP, WPT, PLT files) and Garmin MapSource 4.x (MPS, TXT). Data saving is possible in Polish format only.

    See details here.

  6. How the software may be used?
    GPSMap Edit is freeware. See License Agreement for details.

  7. Should I obtain an additional license from Unisys to work with GIF files?
    Here are some facts.

    GPSMap Edit is freeware whixch opens GIF files for reading only. Futhermore, it really does not include any code implementing LZW decoding algorithm, but uses external code embedded in Windows (which is licensed by Microsoft). In addition, Unisys' patent will expire in 2003.

    You may contact the patent owner to get more details.

  8. How can I feedback to author?
    You may leave message in the guestbook or contact via Email. Bug reports, feature requests etc are welcome!

    Installation, starting, running

  9. What are the hardware and system requirements?
    The answer is here. Pay attention that some features of GPSMap Edit are not available in some versions of Windows; the full list of such limitations is given in the same page. The best environment for the software is Windows 2000 and Windows XP.

  10. How to install the software?
    GPSMap Edit does not have installer now. The program installation does not require special efforts because the software is ready to run. Just download the latest version and unzip it into any suitable folder. Minor exception is usage of PNG and TIFF formats; please see details here.

  11. How can I load a map into the program?
    There are 3 ways:

  12. I load a map but window is empty. Scaling up helps. Why?
    This may be result of incorrect map converting from other formats.

    In general, map contains a few zoom levels for different scales. The levels are defined in the header of map (section [IMG ID]) through parameters "LevelX=", "ZoomX=". If all objects belong to one of level (e.g., to 0-th one), the window will be empty for all other scales.

    You may delete the empty levels to solve the problem. (NOTE: less detailed level should be always empty, according to cGPSMapper' documentation; so minimal number of levels is two).

  13. What do strings "=LevelX" appearing in status bar mean?
    This show active zoom level of the map, corresponding to the selected scale. Mark ">" means that overzooming and "<" - underzooming. Symbol "*" reminds that automatic level selection is turned off: the given level is visualised for any scale (see menu item 'View|Levels').

  14. How can I check that the map loaded violates Polish format limitations?
    "Ready*" status message appearing after map loading indicates that some warning messages was generated. You may see the log using menu command 'File|Error Log'.

  15. Why all bridges have the same direction?
    This is limitation of POI presentation supported by Garmin: they are described as point without direction.

    Note that some of Garmin models never visualize some types of regions at all. For instance, city blocks are not shown in eTrex Vista.

    Moreover, some important kinds of objects have no corresponding region type in Garmin's GPS-navigators. Examples are railway/subway stations, squares, buildings (as polygons) etc.

  16. May I use non-Latin symbols in region's labels?
    GPS-navigators developed by Garmin do support some national alphabets in maps. Unfortunately, current versions of cGPSMapper.exe support just so-called 6-bit coding allowing base Latin characters only.

  17. What does prefix "~[0x" in region label mean?
    This is feature of Polish format used to declare upper case, highway marks and othe issues affecting on labels visualization.

  18. Why GPSMap Edit saves no more 5 digits after dot in coordinates?
    Garmin maps store all coordinates with maximum precision equal to 360о/224=2.1*10-5. So there is no reason to store data in Polish format with higher accuracy.

  19. What does the function 'Join/Split region levels'?
    In Polish format, it is possible to define an object as set of elements distributed over zoom levels ('DataX=' and 'OriginX=') rather than define several single-element objects, one per each level. This approach allows to treat an object as 'whole': user may move, rename, change type, delete etc the object in all zoom levels simultaneously.

    In contrast, TXT files imported from IMG always contain single-element objects. (The intrinsic reason is in IMG format details.) This provides some kind of 'traps and pitfalls' for users while editing.

    So, the 'Join region levels' function combines similar objects from different levels to the joined objects. The 'Split region levels' one breaks the objects to per-level parts back.

  20. What is affine transformation?
    This is term from linear algebra refering to any combination of linear coordinates transformations. In particular these are shift, shear, turn, stretching, compressing and so on.
    Sometimes even vector maps may have such distorsions. Applying affine transformation to these maps may significantly improve their precision.

    In general, affine transformation may be specified by three pairs of points; each pair consists of source point and destination one. In particular, both points of a pair may be equal meaning no shift at the place. If points are equal two by two in each three pairs, the transformation changes nothing.

    To apply an affine transformation to a map, you should have some high-precision geodetic data for the calibration. These may be a raster map (OziExplorer) which is tied as well or tracks and waypoints obtained using GPS-navigator. It is important to make sure that all coordinates are presented in the same datum or be able to convert to WGS84.

  21. How can I apply an affine transformation to my map?
    Follow the directions:

    If something is wrong you may undo transformation and try again with other pairs.

    You may freely change tools temporarily during preparing to affine transformation - to 'Drag' tool or to 'Select' etc - and go back to pairs defining.

    It is recommended to define pairs as distant as possible from each other and from center of the map. This may provide higher accuracy.


  22. What is geodetic datum?
    Datum is like frame of reference. Each point at earth surface is defined as combination of latitude, longitude and elevation. But all the three values depend on origing of coordinates, direction of axes, and accuracy of measured Earth radius and polar flattening. Different datums are used in different countries. As a result, coordinates of the same point may differ in two datums.

    For instance, Russian maps are based on "Pulkovo-1942" datum. The one used in GPS is WGS84. In Moscow region, they are shifted approximately in 150 m. To avoid loss of GPS precision (wich is about 15 m) you should always make sure that all coordinates are defined in or converted to the same datum.

    Functionality to implement

  23. Which features are planned to implement in the future?
    Note the list below does not correspond to the order of implementation.