GRASS with GPS. Data exchange between GPS, GRASS and QGIS. TAKEJIMA, Kiyoshi

Transcription

1 GRASS with Data exchange between, GRASS and QGIS TAKEJIMA, Kiyoshi

2 GRASS, QuntumGIS and etc. kml kml

3 kml kml We can import the data of waypoints, route and track in this menu. Download data into GRASS [Device of the used to import data] is sometimes different in each PC. Start GRASS with any location. -In this case, open the UTM location- File//Vector Map/ Waypoints/Routes/Tracks Using Babel Note, We can import data directly from device. Babel reproject the projection of data to match current location. Default projection of is WGS84. If the setting of your is not WGS84, adequate parameter is need to declare. data is imported as the vector data of GRASS.

4 kml kml and GoogleEarth We use babel to communicate with in the konsole example1. Upload Google earth KML file into the garmin. gpsbabel -i kml -o garmin -f /home/takejima/ sample_upload.kml -F /dev/ttys0 Place/Save as We can save the place mark as the file. There are two file formats. One is KML, the other is Kmz. I recommend you to save the place mark as KML file in case of Using and GoogleEarth with GRASS example2. Download the track data, and save it as the KML file for GoogleEarth gpsbabel -t -i garmin -f /dev/ttys0 -o kml -F /home/takejima/gps/sample_track.kml example3 Download the waypoints data, and save it as the KML file for gpsbabel -w -i garmin -f /dev/ttys0 -o kml -F /home/takejima/gps/sample_waypoints.kml -i format Set input format -f filename Read file -o format Set output format -F filename Write output file

5 , GoogleEarth and GRASS kml kml Vector/Develop map/ Reproject vector from other location This menu enable us to import data from other location even if projections of each location is different After import kml file into the WGS84 lat/lon location, exit the location and start GRASS with UTM location We have to do some complicated operation to use kml file with GRASS. Because the coordinate infomation in the kml files is consisted with WGS84 lat/lon projection. If you are managing maps in the UTM location, the coordinate system is different. In the case of directly download the data from, we do not need to think of of the data. However in the case of kml file, we have to pay attention of reprojetion. kml file, the projection of it is WGS84 lat/lon. So we have to make WGS84 location as the temporal location. In the WGS84 lat/lon location File//Vector maps/various formats using OGR We can integrate the information from GoogleEarth with GRASS.

6 We some times want to upload the GRASS vector data into GoogleEarth or. Following is one of the example to upload the GRASS vector data into. Vector/Develop map/ Reproject vector from other location To upload the kml files into Create Vector data in UTM location Vector/Develop map/digitize Further Study We can reproject UTM data into WGS84 lat/lon The name of imported waypoints are automatically defined. However we sometimes need to define it by ourselves. In such a case, we can use some text editor software like vi to edit kml files. After save the digitized vector data, exit GRASS In the kml file, there is a tag <name>. The character of inside <name> will be the name of waypoints in. The Start GRASS with WGS84 lat/lon location WGS84 lat/lon location is a temporal location to convert the projection for the matching of projection with that of 's one. File//Vector map/various formats using OGR We can export GRASS vector data to kml files

7 kml kml Field Survey and GRASS VERTI: is the inportant keyword to declare the end of header information -essential We some times need to manage some field survey data into GRASS. In the UTM coordinate, the units of it is meter. We can calculate the survey results with, OpenOffice and Calculator The units of the results is meter. That is theoretically, we can manage field survey results with GRASS vector data. B is the declaration of Boundary C is the declaration of Centroid P is the declaration of Points L is the declaration of Line The number of node The layer number The number of centroid The category number The layer number Example of POINT data The most primitive way to do it is, to know your location with UTM coordinate from. You can know the UTM coordinate of waypoints from directly /menu/setup/units/position formats [UTM/UPS] Then make text file. Details of the format of text file is explained in the help file at the v.in.ascii You can import the text file into the GRASS vector data. Example of Polygon data After you have done the calculation of field survey results, you need to make text file like above in case of polygon If you forget the format of that text file, you can use [file/export/vector map/v.ex.ascii]to know the format of text files you have to make. And you can also know the detail of the text file to be made. The keyword is standard vector format in GRASS After you finish to make the text file file/import/vector map/import various vector format using OGR.

8 kml kml QGIS and QGIS also enable us to commucate with data. However, you have to check WGIS plug in manager. Check the tools tools QGIS have a very good interface -easy to use for data handling, however we have to pay attention to projection. If you are opening WGS84 lat/lon location, import and export data with have no problem, but if you are working on Other projection map some projection conversion is needed. Communication with in the QGIS is done via gpx file. If you want to upload the point you have interested in the map, you need to make gpx file. To new create gpx file is difficult on the QGIS. In such case, I recommend you to edit gpx files and add point/line/ data into it which were made by download data.

9 kml kml Note: There is a problem on gpsbabel when you download the data. Files you download from should be consist with 3 file, shp, shx and dbf. However gpsbabel create only shp and shx. It create no dbf file. Normally GIS software like ArcMap can not display its data. That means the shape file created from gpsbabel is incomplete one. This is a problem. So, data which was download with gpsbabel will not work well. I can not recommend you to use its method. But there is one method to improve the situation. QGIS can display the defective shape file. So you can finish its defective shape file via QGIS. Data Exchange between GRASS and QGIS for We do not need to do something when display the GRASS data onto QGIS. But if we want to exchange location data with, a operation is needed on GRASS or QGIS. That is, GRASS data as gpx files or import QGIS data (gpx or shape file) into GRASS data. File//Vector map/various data/ or File//Vector map/ The procedure using the gpx data into the is the same with and. Data Exchange between and shape files babel can directly import and export the shape files. In this case, we use babel in the konsole windows. The command is the followings. Topic : Installation of gbsbabel You can download data as shape file : gpsbabel -w -i garmin -f /dev/ttys0 -o shape -F /home/takejima/shape_gps.shp In the konsole windows, change the user to root $su password: type the password of super user (root) You can also upload shape file into gpsbabel -i shape -o garmin -f /home/takejima/shape_gps.shp -F /dev/ttys0 $urpmi gpsbabel i386.rpm