How-To Test GRASS6

Scope of this page

This pages is intended to users and developers who want to test a GRASS installation (test protocol). As side effect, you can also showcase GRASS 6 using these commands.

Requirements

• GRASS 6 installation (source code and ​binaries download)
• Educational data set: OSGeo Educational data set North Carolina: ​data and ​description.

Extract the NC sample data set for GRASS:

mkdir $HOME/grassdata
tar xvfz nc_spm_latest.tar.gz

Start of the program

GRASS 6 is started either from the menu (if installed therein) or from command line. In all cases, select mapset "user1".

# show available options
grass64 --help

Expected result: the help text should be shown.

# start with current Tcl/Tk based graphical user interface (gis.m)
grass64 -tcltk

# start with wxPython based graphical user interface
grass64 -wxpython

Expected result: the selected graphical user interface should come up.

# start with text based interface
grass64 -text

Expected result: the text user interface should come up.

Re-launch of GUI from command line

# start with current Tcl/Tk based graphical user interface (gis.m)
g.gui tcltk

# start with wxPython based graphical user interface
g.gui wxpython

Expected result: the selected graphical user interface should come up.

Using gis.m TclTk graphical user interface

• To add a raster map, click in GIS manager on "Add raster layer" button,
• Click on word "raster1" which appears in the canvas to enable in the lower part the raster map tool (should already be there)
• In "Display raster maps", select "Base map" button, explode "PERMANENT" mapset, and select map "elevation" (click ok or use double click on map name)
• The map name should have appeared in canvas
• Get second "Map Display 1" window on top, therein click on "Display active layer" button (most left): it should display the elevation map.
• Try to zoom (open with left mouse button a zoom box)
• Create a profile ("Create profile" button)
  • In "Profile window" tool, use left button to select raster map gaina ("elevation" in PERMANENT)
  • Click "Draw profile transect" to draw a transect in the main map window
  • Click "Draw profile" button to draw it. Each transect turn is indicated as vertical line in the profile.
• To add a vector map, click on the "Add vector layer" button
• Click on word "vector1" which appears in the canvas to enable in the lower part the vector map tool (should already be there)
• In "Display vector maps", select "Vector map" button, explode "PERMANENT" mapset, and select map "roadsmajor" (click ok or use double click on map name)
• The map name should have appeared in canvas
• Get second "Map Display 1" window on top, therein click on "Display active layer" button (most left): it should display the elevation map.

Expected result: it should just work.

Using wxPython graphical user interface

Basic map display:

• Click in Layer manager on "Add raster map" button,
• select raster map "elevation@PERMANENT" in properties dialog and click "ok",
• right mouse click in layer tree and choose from contextual menu "Zoom to selected map", map should appear in canvas.
• Try to zoom, to create a profile etc.

Expected result: it should just work.

Digitizing:

• Click in Layer manager on "Add raster map" button,
• select raster map "ortho_2001_t792_1m@PERMANENT" in properties dialog and click "ok",
• right mouse click in layer tree and choose from contextual menu "Zoom to selected map", map should appear in canvas.
• Zoom to houses within the map, zoom one house,
• start "Tools" -> "Digitize" in the map canvas.
• Go to "Select vector map" -> "New vector map", enter "house" as vector map name, "ok".
• Go into the layer manager canvas and click the "Show attribute table" icon,
• Go therein into "Manage table" tab and add a new column "name" as varchar type with length 50. Then "Add", then "Close".
• Now digitize a boundary around the house and a centroid, for both enter "my home" as "name" attribute.
• Leave the digitizer, the house polygon should show up as grey area.

Display various maps in GRASS monitor

(NOTE: not for native winGRASS, but for Cygwin-winGRASS and Unix compliant installations)

As first step on the command line we set the current region to extent and resolution of the elevation raster map. Then we open a graphical map display ("GRASS monitor") and display the map:

g.region rast=elevation -p
d.mon x0
d.rast elevation
d.vect roadsmajor

Expected result: GRASS monitor should open and show the selected maps

Display as shaded terrain map:

d.his i=elevation_shade h=elevation
d.vect roadsmajor

# set barscale position per mouse click into map:
d.barscale -mt

3D visualiztion with NVIZ

# raster map and 2D vector lines map
 nviz elevation vect=roadsmajor

# raster map and 2D vector lines map and 3D vector points
nviz elevation vect=roadsmajor points=precip_30ynormals_3d

Tests: navigate with the puck, interrogate map, etc. (ADD MORE)

Expected result: should not crash at all but show maps as expected

Simple raster analysis

Raster analysis comprises a lot of functionality.

Raster algebra

Normalized Differences Vegetation Index (NDVI) from LANDSAT-TM7:

# set current region/resolution to map:
g.region rast=lsat7_2002_40 -p
# display metadata:
r.info -h lsat7_2002_40
# generate NDVI:
r.mapcalc "ndvi = 1.0 *  (lsat7_2002_40 - lsat7_2002_30) / (lsat7_2002_40+ lsat7_2002_30)"
r.info -r ndvi
r.colors ndvi color=ndvi

# display 2D:
d.mon x0
d.rast.leg ndvi
d.vect streets_wake
# display 3D:
nviz elevation col=ndvi vect=streets_wake

Expected results: the NDVI map should be colorized in near natural colors, see screenshot:

Raster statistics

Univariate statistics:

r.univar ndvi

Expected results: minimum: -0.956522, maximum: 0.978723, mean: 0.190006 etc.

Simple vector analysis

• TBD

Extracting from vector maps

• extract large streets from "streets_wake"

SQL support

g.region vect=schools_wake -p
d.erase

# show all schools in Wake County
d.vect schools_wake col=red icon=basic/circle siz=5

# show a subset of all elementary schools in Raleigh
d.vect schools_wake where="ADDRCITY='Raleigh' and GLEVEL='E'"

Vector statistics

Univariate statistics:

# show available columns
v.info -c precip_30ynormals_3d
v.univar precip_30ynormals_3d col=annual type=point

Expected result: mean: 1289.31 etc.

Transfer raster slope to vector segments

• v.split, v.to.db

Shortest path routing

• NC bus routes... map "busroutesall"

Using QGIS' GRASS toolbox

Start "qgis" within GRASS shell.

• Go menu "Plugins, Pluginmanager, activate "GRASS plugin", OK button: a set of new buttons should appear
• click "Add GRASS raster layer" button, select "elevation" map
• click "Add GRASS raster layer" button, select "elevation_shade" map
• click right mouse button in legend on "elevation_shade" map, move transparency to 40%
• click "Add GRASS vector layer" button, select "roadsmajor" map, select layer "1-line" (level 1 is the topological level), OK

See Also

The following demos are related to the GRASS book, 3rd edition 2008 (based on NC data set):

• ​demo raster
• ​demo vector
• ​demo interpolation
• ​demo image processing