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Friday, October 26, 2012

GIS Training with QGIS - Exercise 2: Editing


1. OpenStreetMap plugin
 a) Start a new empty QGIS project, set projection again to WGS84.
 b) Click Plugins->Fetch Python Plugins. When the list has refreshed, find the
OpenStreetMap plugin and click install.
 c) On the OpenStreetMap toolbar click Load OSM from file. Browse to the directory
Geodata\vector\OSM and load the file sarajevo.osm
 2. Point layer from a table
 a) Now load the shapefile traps from the Geodata\fruitfly directory. Symbolize as red triangles.
 b) Locate the CSV file trap_locations.csv in the Geodata\fruitfly directory.
 c) Import the CVS file using the Delimited Text plugin. Choose ',' (comma) as the delimiter.
 d) Convert the trap locations to a shapefile (right-click on the layer name). Name it traps_tbl.shp
and save in the Geodata\fruitfly directory. Now load the new shapefile (“Add Vector Layer”
button).
 3. Digitize new point layer
 a) Zoom in to the traps layer.
 b) Click on the “New vector layer” button to create a new vector layer within QGIS, as a point layer
with two columns: Trap_ID as Whole Number, and TrapType as String. Call the layer
traps_digitize.shp in the Geodata\fruitfly directory.
 c) Start editing this new layer and digitize ten new points south of Sarajevo. Give the points Trap_ID
numbers 201, 202,...210.
 d) Save the layer. Save the project  in Geodata\exercises as fruitfly.qgs
 4. Merge three point layers into one
 a) Start editing the traps.shp layer
 b) Copy all points from traps_tbl into traps by activating the traps_tbl layer, and selecting all
traps in that layer. Click the copy button. Then activate the traps layer and use the paste buttons to
insert all the points from traps_tbl into traps.
 c) In the same way, copy all points from traps_digitize into traps.
 d) Move some of the points to make a better distribution of traps.
 e) Save changes.
 5. Edit attribute table
 a) Open the attribute table of traps, and begin editing
 b) Enter an appropriate value for each trap in the column “TrapType”.
 c) Save the edits and save the project.

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