2011-05-25

Since QGIS has simple and poverful GRASS GIS implementation, I found that more often I`m using this Grass version, not standalone Grass GIS.
There has been some needs for my friends doing very basic and simple things, but as it takes longer if someone don`t know QGIS and Grass well, I made some tutorials.

This one explains how to define coordinate system for project for correct distance and area measurements, and correctly add scalebar.

In this next video the DEM is loaded in Grass GIS database from QGIS and visualised through NVIZ. All under windows xp.





The next video shows how to georeference an image file. I`m using very dummy image file as example... ;)



The next video shows how to rasterize vector contour lines, how to interpolate rasterized contour lines and very basic mapcalc stuff - how to get difference between two different DEM`s.



This video shows a bit complicated raster analysis example. There is a dummy JPG raster file where each cell should contain values 0 (black) and 255 (white). But because it`s compressed and it`s JPG, there are cells between defined values. With simple mapcalc usage it`s possible to define - are these cells could be counted as black or white.
of course, it`s possible to do it just writing script in shell, but Grass allows create these scripts in very user friendly way.



But sometimes there are needs to manipulate with LIDAR data. And here LAStools are very handy. LAStools could be downloaded from here. But as they are command line tools, the easiest way is to write BAT`ch file (in windows).
So here is example - how to manage it.

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