Kempen, Rhineland (Germany) -
For mapping applications there are free map services like Google Earth, Google Maps, OpenStreetMap and OpenTopoMap available for everyone who is interested.
A frequently needed task is the display of own geodata like points, lines and polygons as objects on the maps provided by these services.
The geographic objects can be located on the go via GPS with a smartphone, tablet, satnav or notebook, or it can be included in the planning process in a different way.
With the program TRANSDAT by KilletSoft geodata from any source can be converted into the file formats KML and GPX. These file formats are used by mapping software which utilize map services for the display of external geodata on maps or in satellite images. The file format KML (Keyhole Markup Language) can display the graphic elements like point, line, polygon with attributes like point color, line width and fill color in map services. The GPX file format (GPS Exchange Format) serves the exchange of geodata between programs and provides map services with geodata as waypoints and tracks. On the right, an example with external geodata on a satellite map is displayed with the GPX/KML Viewer by the company SeaWellSoft ( http://seawellsoft.com).
TRANSDAT transforms geodata stored in Text, SDF, CSV, xBase, ArcGenerate or Shapefiles from any Coordinate Reference Systems to the required Geographic Coordinates on the WGS84 ellipsoid, and writes them to KML and GPX files. In addition to the required coordinates and for the purposes of labeling the objects, TRANSDAT can write an object name and an object description into the KML or GPX file to be generated. On the left, the start screen of the program TRANSDAT is displayed. If you click it, the main window of the programm with the multi language user interface is zoomed in.
Example for the use of free map services
By way of illustration I would like to exemplarily address the solution of a request brought to me by a customer. The customer owns an EXCEL table in which a large number of wooden poles for electricity supply in a rural region are listed. The customer has to make local checks on the wooden poles at regular intervals. He would like the wooden poles to be marked on a map which is displayed on his outdoor device. Such a device can be a notebook, tablet or smartphone for example. With the aid of the activated GPS on the map, the customer wants to locate the wooden poles and be able to directly reach them with his company vehicle. In the further course first is shown how to create a KML file with TRANSDAT. Afterwards several options for the display of the wooden poles in map services using the KML file are described.
Here is an excerpt from the EXCEL table Woodpoles.xls which I have altered for data protection reasons and cut down on ten data records for demonstration purposes. The data fields "UTM_East" and "UTM_North" describe the location of the wooden poles in UTM coordinates of the Reference System ETRS89. A consecutive numbering of the wooden poles is saved in the data field "PoleNo". These numbers are to be displayed along with markers on the map by one of the map services. The field "Description" contains the descriptions of the wooden poles which have been severely shortened in this instance. Important information like addresses or conditions of the wooden poles could be filled here. Most map services allow displaying a description by double-clicking on the marker.
Given that TRANSDAT cannot directly work with the XLS format (EXCEL workbook), first of all the table needs to be converted into a suitable data format. For this purpose the formats CSV (Comma-Separated Values) or dBase (Database Format), which can be easily created with EXCEL, are suitable. For demonstration purposes I use the CSV format here. Firstly the rows and columns in EXCEL, which are to be exported, are marked. Then the EXCEL Export Window is opened with the menu option "File / Save As…". Here you can determine the file location, assign a file name to the wooden pole file and select the file type "CSV". By clicking on the button "Save" the file Woodpoles.csv is created. In the first row the field descriptions are stored. All data fields in the CSV file are now separated from one another by semicolons.
Preparing the geographic objects with TRANSDAT
The CSV file now can be used for generating a new file in the file format KML. But first a few settings need to be adjusted in the program TRANSDAT for the coordinate transformation. The locations of the wooden poles are available in the CSV file as UTM coordinates in the reference system ETRS89. But map services always use Geographic Coordinates with the worldwide reference system WGS84. This kind of coordinates are also generated by GPS receivers and transferred to the map service installed on the display device. This way it is ensured that the current GPS position on the map will be compatible with the locations of the wooden poles displayed there. For lack of space I am only showing an excerpt from the TRANSDAT main window with the settings that are important for the coordinate transformation.
Now the settings for the input and output files need to be adjusted. By clicking on the button "Work with data files" a further window for the file configuration is opened. Also here, only an excerpt of the window with the required settings is displayed.
In both drop down listboxes the formats for the input and output files are set. There is an input file in CSV format and an output file in KML format is to be generated. For the input file the semicolon is chosen as data field separator. The position of the coordinates in every data record of the CSV file starts in the third data field. There you find the east value of the UTM coordinate pair which is complemented by the north value in the fourth data field. The second data field shows the point name which is written at the point position in the map service. We use the first data field as point description which is displayed in the map service by clicking on the point. The first row of the CSV file has to be filtered because it only contains the data field descriptions. They are not required for the KML file to be generated. On the bottom right, we select the option for using the coordinates as waypoints. With the button "Open an input file" the CSV file must be selected. With the button "Open an output file" the file path and file name for the new KML file is determined.
Because the settings are complete now, the button "Calculate target coordinates" is clicked in the main window. In case everything has been done correctly, a confirmation message will be displayed. By the way, the last coordinate calculated from the CSV file can already be displayed as a single point in the map services OpenStreetMap, Google Maps and Google Earth. Simply click on the corresponding button at the bottom right in the TRANSDAT main window. Of course, precondition is that Google Earth is installed on the computer or that there is an internet connection. The single point display in map services is a feature of TRANSDAT which works with all file-based and direct coordinate transformations.
We do not want to display only a single point, but all geographic objects registered in the KML file that has just been generated. You can now display all wooden poles in Google Earth by clicking on the button "View the output file" in the file configuration window. For lack of space the excerpt from the program Google Earth illustrated below is reduced to a minimum. On the satellite image you can see now ten wooden poles with markers and point names at their locations. If you click on a marker, the point description will be displayed. By zooming in on Google Earth you can see that the marker positioning is identical with the locations of the wooden poles. In this highly zoomed section you can see the pole with the number 435 and its shadow. The tip of the marker points exactly to the pole step.
KML file generated with TRANSDAT
The KML file that has just been generated is now available for the display of the geographic objects with the most map services. The file must be copied to the display device and made available for the installed mapping software.
In a KML file geographic objects are stored in XML syntax. There are objects for points, lines and polygons. All coordinates are always stored as Geographic Coordinates with the sequence longitude and latitude. In KML files the WGS84 (World Geodetic System 1984) is always used as reference system.
On the right, you can see an excerpt from the KML file with the data of the first four wooden poles. The file contains point objects of the ten wooden poles as <placemark> items with the point names <name>, the point descriptions <description> and the point coordinates <coordinates>. The KML file has a readable format so that the entries can subsequent be modified with an editor. But make sure that after modification the file is saved with the UTF-8 character encoding so that later the umlauts in the point names and point descriptions are displayed correctly on the maps.
As the objective of the customer, the generated KML file is to be displayed and navigated on a mobile display device independently of the program TRANSDAT. There are many ways to realize this. In the following explanations only a few possible solutions are briefly addressed.
Display and navigation of geographic objects with mapping software
The KML file can be used independently of the program TRANSDAT on all display devices with installed Google Earth. There are three options for displaying the wooden poles on the map background:
Then Google Earth automatically provides a map section that includes all geographic objects.
An example is illustrated further above.
An interesting program for displaying own geographic objects from KML or GPX files onto the map background of different map services is the mapping software GPS Mate by the engineering office Oestreicher in Munich (Germany). The software supports online maps like OpenStreetMap, OpenCycleMap, OpenSeaMap, Google Maps, Bing Maps or Nokia OVI Maps. Layers in various file formats can be loaded into the program. The route guidance allows the GPS outdoor navigation to the displayed objects. The current GPS position is directly displayed on the maps. The software can be installed on tablets, smartphones, PCs, notebooks and mobile navigation systems (PNA). On the left, you see the wooden poles on a smartphone which are displayed with GPS Mate from our KML file on map material provided by OpenStreetMap. At the URL http://www.gps-mate.de you find more information about the versatile yet inexpensive software.
In Google Maps KML files cannot be imported directly. But in contrast, it is easily possible with Google My Maps, if you are logged in with your Google account. In Google My Maps up to 10 layers can be created and filled with own contents from KML and GPX files. Own geographic objects then can be displayed and navigated on all devices supported by Google. Here is a small map section with the ten wooden poles, that has been created with the Google My Maps account of KilletSoft. By double-clicking on one of the displayed markers the point description will be activated. As desired by the customer, you can navigate from any location to each of the wooden poles.
At the URL http://www.atlsoft.de/gpx the company ATLsoft in Plattenberg (Germany) provides a GPS Viewer with map material supported by the German Federal Agency for Cartography and Geodesy (BKG). Optionally, maps by the map services OpenTopoMap or Google Maps can also be used here. You can simply drag the KML file from the Windows Explorer onto the map interface and the objects contained therein will be marked on the map. By clicking on a marker the number of the wooden pole and the description are displayed. Here I have prepared a section with the wooden poles on a map with the GPS Viewer by ATLSoft.
GPS-Empfang mit TRANSDAT
In addition to the possibility to convert geodata of any formats into KML and GPX files, GPS positions can be received directly with the program TRANSDAT. With the integrated GPS receiving function, GPS signals can be received via a GPS antenna and then be analyzed. When using a notebook, an inexpensive GPS mouse (starting at 20 Euro) is used as antenna. This way it makes possible to determine position data in the form of coordinates and altitudes, speed and direction parameters and the exact time and to store this information in a GPS file. After finishing a measurement series, coordinates and additional information contained in the GPS file can be transferred to all file formats supported by TRANSDAT. Of course, also KML and GPX files can be generated for further processing of the received GPS positions in free map services.
On the website http://www.killetsoft.de you can find detailed information about the Coordinate Transformation Program TRANSDAT. You can also download a free trial version there. TRANSDAT performs coordinate transformations fast and with high accuracy. Worldwide the transformation software supports thousands of coordinate systems, geodetic reference systems and datum shifts, user-defined systems, 2D/3D transformations, INSPIRE, NTv2, HARN, EPSG, GPS, continental drift and more. The coordinate converter reads and writes the file systems Text, CSV, SDF, dBase, Arc-Shape, Arc-Generate, KML, GPX and others. Also: Outdoor GPS reception, viewing in Google Earth, Google Maps and OpenStreetMap, Polygonal Validity Scopes in NTv2 files, multilingual user interface.
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