GPS & Dirt Bikes
Should you consider getting a GPS (Global Positioning System) unit for your dirt bike and trail riding? First let's take a look at what GPS does.
There are over two dozen GPS satellites hovering overhead, emitting signals. A GPS unit (Garmin being one of the most well-known brands) will calculate it's location on the globe by triangulating it's position relative to 3 or more of those satellites. The more satellites being received, the more accurate your GPS position will be.
Prior to the year 2000, GPS signals included something called selective availability. In short, the signal was made fairly inaccurate, on purpose. Only the military had access to the better, far more accurate signal. However, selective availability has now been removed, and even the most basic GPS units are accurate to within 3 to 10 meters, and many of the newer models are even more accurate.
Most newer GPS units also use WAAS. WAAS, or Wide Area Augmentation System is a system of satellites and ground stations that provide GPS signal corrections for even better position accuracy -- up to five times better. And there's no need to buy additional receiving equipment or pay service fees to utilize WAAS.
With a GPS unit, you can locate trails for dirt bike riding, if you have the latitude and longitude coordinates. If you discover a trail, you can note the coordinates of the starting point, or use your GPS unit's tracklog feature. With a tracklog, you can keep it stored on your GPS unit – which will also allow you to backtrack – or download the coordinates to GPS software to create printed maps. A great program for this is Mapwel, which I'll discuss in more detail further down the page.
A GPS unit will also allow you to participate in geocaching – a great addition to trail riding. Geocaching is basically a high-tech treasure hunt. Caches are hidden and listed on the Internet (try Geocaching.com) with only their coordinates and sometimes additional clues. The caches generally include a logbook and pencil to record visitors, and tokens or prizes that can be traded.
Most newer GPS units include maps that you can follow – however there are very few undocumented trails on those supplied maps. One great option is creating your own custom maps – I recommend Mapwel. Mapwel is free to try and quite reasonably priced if you want the full set of features.
One thing I like about Mapwel is the ability to customize a map for my Garmin GPS. For example, there are some great trails I love to ride in a wooded area, but they don't show up on the supplied MapSource maps. After riding the trails and recording my routes on the tracklog, I can download the waypoints and routes to Mapwel. Using those coordinates as a starting point, I can draw in trails and reference points like hunting cabins, fences, etc. I can even use scanned in maps or downloaded aerial shots as a reference – kind of like tracing. Mapwel then converts the map into a GPS compatible format and uploads it to my Garmin. Now, when I ride, I can see where I am on the actual trail, instead of just being a dot in the middle of a detail-less map.
The biggest tip I can offer when creating maps is to calibrate it from GPS readings you've taken with YOUR unit, on location, whenever possible. Google Maps and Google Earth can be off by quite a bit.
I've included a list of some of the Mapwel features from their website below. Or just click here.
Import of files, files merging
Mapwel supported GPS units require maps in vector format. Therefore, easiest way of how to create map for GPS is to import files in ESRI *.shp, *.gpx or other vector format into Mapwel, merge them together and assign proper type to all map objects. Mapwel also supports import of raster images and their automatic and manual vectorization.
Projections and datums
imported files in both vector and raster format (especially *.shp files) may use various projections and geographic systems. Mapwel supports hundreds of the commonly used systems, including UTM (Universal Transverse Mercator). Internal format of map data in Mapwel is WGS84, because this format is also internal format of the GPS units. Although user can select various coordinate systems in GPS, coordinates are always calculated from WGS84 format. Therefore, Mapwel converts all input data into WGS84.
If you need to get raster image into GPS with just a few mouse clicks, this is the right tool for you. Mapwel provides Automatic "one-click" vectorization of raster images (satellite imagery or scanned maps). Garmin units do not allow to load raster image directly into the GPS and use it as a map. Therefore, this function automatically vectorizes raster image and creates vector file compatible with GPS.
Mapwel provides two approaches to establish relation between raster image and map coordinate system: 1. direct calibration, 2. separate image editing and map georeferencing. In both cases, result is a map with Lat/Lon grid parallel to the screen edges and coordinates assigned to left, right, top and bottom edge of the map. Click here to find out more >>
User defined styles
GPS units use basic (pre-defined) and user-defined sets of polygon patterns, line styles and symbol icons. Mapwel provides easy-to-use editor of user styles, which are supported by most of the new Garmin GPS. Click here to find out more >>
Map can be drawn from the scanned paper chart, aerial photos, satellite images and/or with use of tracks and waypoints imported from your GPS. Mapwel allows to draw map with use of straight lines and curves. When drawn with curves, map can be uploaded into the GPS with chosen precision/data-size ratio. User can apply Contrast, Brightness and Gamma filters to the scanned chart or satellite image to adjust the background for convenient drawing of vector objects on the top. To make drawing of complex objects easier, Mapwel provides Opening in the Area tool.
Mapwel tools help to manage maps in your GPS, which are normally not accessible, or hard to manipulate because they are all merged into a single file.
' Add maps to other maps in GPS' function allows to add your map to those already present in the GPS memory. 'Delete specific maps in GPS' allows to erase individual maps from your map set. 'Merge IMG files' alllows to combines several maps into a single file for use with Nüvi, Zümo, Colorado, Oregon or unit, which memory is directly accessible from Windows.
Other Mapwel tools help to create map faster. For example, 'Create Circle around Point' function for aviation maps creates 'circles' of defined radius around all selected points. Very large 'circles' look deformed near poles, because of coordinate system projection. However, real-world distance from center to any point on the "circle" is the same.
Unlike the other Mapwel drawing tools, which are based on the precise manual placement of the nodes, curves and lines, Freehand tool allows to draw many of the Mapwel objects very fast with a free hand. Strokes are automatically converted into the chosen style. After conversion, strokes can be edited as other vector objects (node by node).
This is another tool for faster vectorization of the raster image. It allows to vectorize one object (or set of similar objects) at once, but it cannot vectorize whole map with different types of objects at once. Tracing should be repeated for respective types of objects (filled areas, roads, rivers, etc.). Trace tool works on images with any common color depth (including True Color and bi-tone) that are sufficiently clean.
Object Inspector box at right side of the main Mawpel window displays information about respective map objects and simplifies the object manipulations. It also allows to select one or several objects in the work space.
Mapwel allows to draw the map in any colors you choose and the 'What you see is what you get' interface (WYSIWYG) shows how the map will look like on the color or monochrome GPS display. Mapwel also simulates the Nighttime and Marine color modes. When drawing the map, use display mode tabs in the left bottom corner of the Mapwel screen to review your map in the real GPS colors.
Properties of Objects
Each object has adjustable properties like name, comment (text that is displayed in GPS when cursor stays on top of the object), type, max. zoom level, etc. POI (points of interest) may have address and phone number assigned.
It is also possible to define properties of the whole map, like name, copyright text, address format, internal map ID, map draw priority and zoom levels of map layers.
Automatical Object Splitting
GPS rendering engine requires large areas and lines to be split into smaller objects because of the data structures limitations and speed of map rendering. Mapwel splits all objects automatically without loss of the map detail when it uploads map into the GPS. User does not have to bother about the object size or detail limitations. Splitting process runs internally without user even knowing about it.
Both technical and software limitation of GPS units restrict accuracy of maps (see the Accuracy table). This restriction is related to the map scope. It means that very large map is represented in GPS with lower accuracy than the small or normal size map. Mapwel automatically converts all map data into the best possible accuracy level.
Map Uploading and Export
Finished map can be saved into Mapwel *.mpw file format, exported into *.img, *.kml or other supported format, or uploaded directly into the GPS. Export of map into other than *.mpw file is supported by Mapwel Advanced version only. Mapwel includes separate MapUpload program for loading *.img files into the GPS. MapUpload also allows to pack several img files into a single executable file to distribute to your friends or customers.