Howtos

From TrekBuddy

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Fundamental HOWTO Maps and Atlases.

1 Maps
2 Atlas
3 Installing a downloaded map
4 GPX File format
5 TODO

[edit] Maps

Maps technical information

Raster maps

Trekbuddy has support for raster maps. Such map consists of raster picture file and GPS metrics file, known as calibration file. Map picture format can be any popular graphics format like png, bmp, jpg, tiff etc. More information about digital maps can be found in Wikipedia GIS. Raster maps are prepared with different resolutions in DPI (dot per inch). For mobile phone usage map resolution should be similar to device screen resolution, it means 150-200 DPI. Calibration file should be OziExplorer .map format file or Map Calibrator .gmi file. Due lack of some informations, second one is suggested for WGS84 maps mainly. Both programs can be used to produce calibration files for free. Calibrated raster map should be adopted for Trekbuddy usage, fortunately easy to use Tools like TB Cutter exists to do it. Maps can be included in atlas and grouped as layers, ie road, topo, street plan etc. Atlas or maps can be saved to tar format to reduce number of files.

Map datums and projections

Trekbuddy has build in some datums and projections to support different maps. Hardcoded datums are WGS84, AGD66, CH-1903, NAD27 (CONUS), OSGB36, Ireland 1965, RT90, S-42(Russia). For other datums custom definition can be used, with 3 points Molodensky transformation to WGS84 datum. The list of tested custom datums is available on forum. Similar like datums, Trekbuddy includes few basic projections, like Mercator, Transverse Mercator (TM) and Universal Transverse Mercator (UTM). Transverse Mercator projection is implemented as definiable, so a lot of country specific TM grids can be used. Some other country specific grids are predefined too, like BNG, IG, etc. Information about map datum and projection is taken from calibration file. If parameters are unknown, TB defaults to datum selected in settings, default grid is UTM.

[edit] Atlas

An atlas is a set of maps which can have different detail-levels or sizes (layers). Trekbuddy automatically selects the right map out of the atlas while you move.

You can switch layers with 7, maps with 9 key.

TODO how to create an atlas out of eg 2 existing maps

[edit] Installing a downloaded map

Download a map or an atlas. Look for links here.
- Further steps were tested with the file praha.zip (Czechia). Other maps may be packed differently!
Create a temporary folder for the map on the disk of your PC, e.g. praha. Unzip the entire praha.zip into this folder, keeping the original subfolder structure.
- You may note that the ZIP file contains embedded TAR archives. For most devices you do not need to extract files from these archives, as most devices support the TAR format!
Copy the folder praha into the Data dir of your phone, e.g. into Other/TrekBuddy folder on the memory card. (The data dir can be set in Settings / Basic.)
Run TrekBuddy. Select the right menu (Další) / Load Atlas. Scroll down to praha/ and click on "Select". You will be offered to make this Atlas your default.
Select left menu "Start BT-G" (connect to the bluetooth GPS). If you are in the area covered by the map, TrekBuddy will display your position on the map.

[edit] GPX File format

TrekBuddy 0.9.79 creates and reads GPX waypoint files in the following format:

<?xml version='1.0' encoding='UTF-8' ?>
<gpx version="1.1" creator="TrekBuddy 0.9.79" xmlns="http://www.topografix.com/GPX/1/1" 
 xmlns:rmc="urn:net:trekbuddy:1.0:nmea:rmc" xmlns:gsm="urn:net:trekbuddy:1.0:gsm">
  <wpt lat="47.044470906" lon="8.314939141">
    <ele>452.0</ele>
    <time>2008-06-26T20:39:34Z</time>
    <name>Luzern, CH</name>
    <cmt>A nice city in Switzerland next to a big lake</cmt>
    <link href="images-2008-06-26-20-39-34/pic-1.jpg" />
  </wpt>
  <wpt lat="47.062317960" lon="8.304618467">
    <ele>491.0</ele>
    <time>2008-06-26T22:14:15Z</time>
    <name>Libellenstr</name>
    <cmt>2nd waypoint</cmt>
  </wpt>
</gpx>

Most geo applications allow to export as GPX, so you can create/modify waypoint collections easily your own PC. Some hints:

lat and lon are in decimal degrees, WGS84 datum.
Altitude <ele> is in meters
Time is UTC, not local time, and spelled in ISO 8601 format
For <name> and comment <cmt> use only a-z A-Z 0-9 ,.-_ Umlauts and so on in one waypoint will cause TrekBuddy to reject the whole file and to issue the message No waypoints found in <filename>. Same message appears if you do not close all tags correctly.
Snapshots (pictures for waypoints) are stored as links, e.g. <link href="images-2008-07-07-11-47-57/pic-1.jpg" />
Further waypoint elements defined in GPX standard are ignored by TrekBuddy, e.g. description <dsc> or waypoint specification '<type>. If they appear in the file, TrekBuddy will read the file but not use the additional information.
The file may be in UTF-8 format, but TrekBuddy will accept happily files is in usual ANSI format although xml encoding is set to 'UTF-8'.