The data set
The Global Land Cover Facility offers, amongst many other data sets, the MODIS Vegetation Continuous Fields data set for download. These are layers that contain proportional estimates for vegetative cover types (woody vegetation, herbaceous vegetation, and bare ground). As such they are very suitable depict areas of heterogeneous land cover.
Their MODIS products differ from DAAC editions by coming in GeoTIFF format, geographic coordinates, WGS84 datum, and a tiling system designed to fit well with Landsat imagery. Currently the collection 5 is available, which contains proportional estimates for woody cover vegetation for the years 2000 to 2010. It can be downloaded as tiles (195 in total) via a ftp server.
Below I’ll provide an example Continue reading
The Multivariate Environmental Similarity Surfaces (MESS) is an index that represents how similar a point is to a reference set of points, with respect to a set of predictor variables (Elith et al (2010). The function was first implemented as part of the Maxent software package, but is now also available in R and GRASS. Below, I will compare how fast the different implementations are. Continue reading
And it is looking great. I have been using the master (development) version for some time now, so I can tell you out of experience that this release rocks! Some of my favourites are the greatly improved map composer, great new styling features, integration of Sextante in QGIS core and much improved stability. For a list of major changes and new functions, go here. But, of course, don’t take my word for it, but check it out yourself and get a copy from the QGIS website. Continue reading
Some time ago I came across this post from Sylla Consult about a script to calculate forest fragmentation index suggested by Riitters et al. (2000). Obviously, it can be used for any land cover type, so perhaps landscape fragmentation index would be a better name. Anyway, the script r.forestfrag.sh is available from the GRASS-addons page.
Unfortunately, it only worked with GRASS 6.4. Because I mostly work in GRASS 7.0 I adapted the script to make it work on GRASS 7.0. I also added some additional options and changes: Continue reading
Getting the coordinates of a location on Google maps isn’t as straight forwards as one may expect. But, as usual, if you know how, it is easy enough. And, there are actually several ways. Continue reading
What if you want to get a number of raster maps from a mapset to bring with you? Or you want to back up a number of layers, but not the whole mapset? Of course you can export it as e.g., an ascii or geotiff, but that won’t save the colour table, attributes, etc. So what then? Well, check out the r.pack package. It provides a script that compresses a raster layer, including colour table etc. You can restore the raster map from the export file to the same or another computer using the accompanying add-on r.unpack. Continue reading
An announcement on the QGIS mailing list about NIWA Quantum map made me curious. How is this going to differ from QGIS? As it turns out, NIWA Quantum map is basically QGIS with a simplified interface, i.e., it has some GIS functionality hidden or removed to be less confusing for users not familiar with GIS. They used the customization options to disable the editing functions, so users can enable that if required. I wonder though why they did not do the same with the analytical functions, rather then removing it all together.
It furthermore has a custom plugin added to provide easy access to a number of data layers for New Zealand. As these are WMS or WFS data sources, you can of course open them in QGIS too, or any WMS or WFS compatible software for that matter.