Mapsnigeriainitiative appreciates all her viewers and readers for their continued interest during the one week break. We had a successful field work and brought back lots of tips and techniques.
For this week, the blog will focus on the GPS receiver and how we can upload data from georeferenced images- either satellite imagery on google earth or vector maps produced in GIS softwares- ArcMap and QGIS.
Uploading data into a GPS receiver is an essential know-how for the Users of GPS technology. Raster and Vector types of data can be loaded into the GPS receiver. The GPS receiver can only accept and read vector data in its native file format GPS Xchange *gpx*, which means data from the pc will have to be converted to other formats using specialized softwares. GPS receivers accept and display custom maps like the Garmin models that do this in KMZ format.
It is very relevant to know how to upload data in the GPS receiver because it will be useful for navigation, which is a principal application of GPS technology. To find the way to a location using a GPS receiver, one needs the geographic data of that object or phenomenon to be pre-loaded into the GPS receiver. In addition, not only must it be Uploaded, it must be loaded in the right format. Loading data into the GPS receiver is a process that allows the user or the mapping professional or enthusiast to work with features physically on the ground.
For example- A fire truck cannot find its way to the scene of the fire as quickly as possible if it hasn’t uploaded the location (geographic coordinates or spatial data) of that emergency scene unto its onboard GPS. So also an inspection team cannot easily navigate to the location of an Oil spill if it doesn’t have the GPS coordinates of that location pre-loaded into the GPS receiver.
Having explained the relevance of pre-loading data on the GPS, we know GPS data are stored in the receiver in three forms- Waypoints (Point feature), Routes (Line feature) and Tracks (Polygon feature). Features in a GIS can be in any of these forms, thereby during the loading process, care must be taken to put the features in their proper form.
For example- A list of waypoints joined together to form a route will represent a line feature in a GIS. To upload this line feature as a track may bring about disorder during the mapping process. Loading a line as a waypoint or polygon can upset the mapping process when going to inspect a building (polygon or waypoint feature depending on scale).
We will need to use the right tools for the job. There are quite a good number of softwares that can do the job but we in this blogsite endeavor to go for the most cost effective tools available online, particularly open source freewares. We also avoid GPS receiver proprietary software so it doesn’t appear we are promoting any brand’s wares.