Point coordinates to polygon – part II

In my previous article, I showed how you can convert point coordinates into a polygon vector layer in QGIS. So how about GRASS GIS? Like in my previous post, let’s assume you have a text file with two columns with the coordinates. With the v.in.ascii function you can import this text file as a point layer. Next, you can use v.hull or v.delaunay to create polygon layers.

With a little bit more work, you can convert the above mentioned text file into a ASCII vector file. Continue reading “Point coordinates to polygon – part II”

Point coordinates to polygon – part I

Articles about field studies sometimes (but not always unfortunately) contain coordinates delimiting the boundaries of the field study. What if you want to view those boundaries in e.g., Google Earth? In other words, how to create a polygon layer based on point coordinates? Let’s explore some ways to do this in QGIS. Note that all plug-ins mentioned below are either part of the QGIS core, or can be downloaded with the plug-in manager. Continue reading “Point coordinates to polygon – part I”

Exporting vector layer as kml in QGIS

In my previous post I described how to export a vector layer from GRASS GIS as kml file. The key was to use the dsco parameter to define the columns that should be used for the Name and Description fields in your kml file.

In QGIS you use the ‘save as’ option in QGIS. You can get this using the context menu (right click mouse on the layer) or the menu ‘Layer | Save as..’. In the menu that opens, there are two fields under the header ‘OGR creation options’; ‘Data source’ and ‘Layer’. Continue reading “Exporting vector layer as kml in QGIS”

Exporting point file as kml in GRASS GIS

The v.out.ogr function in GRASS GIS let you export your vector layer to any format supported by OGR (it is basically an interface to the GDAL/OGR function ogr2ogr). This includes kml files. E.g.,

v.out.ogr input=labels layer=1 dsn=/home/paulo/test.kml format=KML

will export the vector layer ‘labels’ as the kml file test.kml Continue reading “Exporting point file as kml in GRASS GIS”

A map of Madidi National Park

See The grunts of the jaguar on Forestalis for a nice story by Jeroen van der Horst about his trip in Madidi National Park in Bolivia. I had no clue where to find this park so decided to look it up, and to share the result for those interested…

As it turns out, it is fairly easy it is to make your own map and share it through Google maps. First you need to create a kml layer with the park boundaries. This can easily be done in QGIS using the QGIS plugin OGR Layer converter. To enable this plugin, go to the menu ‘Plugins | Manage plugins’ and select ‘OGR Layer Converter’. Now you will find ‘OGR Converter’ in the drop down menu of Plugins. Next: Continue reading “A map of Madidi National Park”