Difference between revisions of "Education Material Development"
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== Unit AM4 Basic analytical operations == | == Unit AM4 Basic analytical operations == | ||
| − | === Exercise Data == | + | === Exercise Data === |
'''Type of Data''' | '''Type of Data''' | ||
| + | Four simple datasets are used for these examples including 3 vector and at least one raster data file. Each file should generally overlap the region of the other files so that comparison operations can be done in the exercises: | ||
| + | # points - several dozen points roughly grouped together | ||
| + | # lines - a simple network of lines would be ideal | ||
| + | # areas - one or more polygons | ||
| + | # raster - with some simple grouped classes, not too noisy and similar in appearance to points, lines or areas. | ||
'''Specific Examples''' | '''Specific Examples''' | ||
| + | All examples in this instance of the training are from the North Carolina demonstration dataset shapefiles and grids. | ||
| + | # points - bus stop locations - ''busstopsall.shp'' | ||
| + | # lines - stream network - ''streams.shp'' | ||
| + | # areas - lakes - ''lakes.shp'' | ||
| + | # raster: | ||
| + | ## a single point-like feature class - ''facility.grd'' | ||
| + | ## road linework - ''roadsmajor.grd'' | ||
=== Buffers === | === Buffers === | ||
| + | |||
| + | '''Method''' | ||
| + | # open GIS application | ||
| + | # add shapefile or raster layer to the map view | ||
| + | # zoom to the extent of the layer | ||
| + | # select ''buffer'' geoprocessing tool | ||
| + | # enter required parameters and options: | ||
| + | ## ''input layer'' - the layer that the buffer operation will be applied to | ||
| + | ## ''output layer'' - the new file that will be created and include the buffer features. | ||
| + | ## ''distance'' - the distance from the input features that the buffer will be created at | ||
| + | ## options - including the option to ''dissolve'' the resulting features by merging the buffer features together instead of retaining the individual buffer lines of overlapping buffer perimeters. | ||
| + | |||
| + | '''Exercise using QGIS''' | ||
| + | # open QGIS | ||
| + | # Load the data layer. Using menus at top of screen select '''LAYER -> Add Vector Layer''' | ||
| + | ## Press '''Browse''' button | ||
| + | ## Navigate to the folder holding the sample datasets and select '''busstopsall.shp''' and press '''Open''' button | ||
| + | ## QGIS will automatically zoom to the extent of the bus stop features | ||
| + | # Run the buffer process from the menu: '''TOOLS -> Geoprocessing Tools -> Buffer(s)''' | ||
| + | ## Set the '''Input vector layer''' to '''busstopsall''' | ||
| + | ## Enter '''Buffer distance''' of '''20'''. This will be 20 metres. | ||
| + | ## Set the '''Output shapefile''' by pressing '''Browse''' button. Navigate to the data folder and enter the new filename as '''busstops_20m_buffer.shp'''. Press '''Save''' button to select that filename. | ||
| + | ## Press '''OK''' button to run the process. | ||
| + | # After running, the system asks '''Would you like to add the new layer to the TOC?''' select '''Yes''' and the resulting shapefile will be added as a layer in your map view. | ||
| + | # Buffer(s) window remains open. Press '''Close''' to close the window. | ||
Revision as of 13:00, 5 November 2009
Unit AM4 Basic analytical operations
Exercise Data
Type of Data Four simple datasets are used for these examples including 3 vector and at least one raster data file. Each file should generally overlap the region of the other files so that comparison operations can be done in the exercises:
- points - several dozen points roughly grouped together
- lines - a simple network of lines would be ideal
- areas - one or more polygons
- raster - with some simple grouped classes, not too noisy and similar in appearance to points, lines or areas.
Specific Examples
All examples in this instance of the training are from the North Carolina demonstration dataset shapefiles and grids.
- points - bus stop locations - busstopsall.shp
- lines - stream network - streams.shp
- areas - lakes - lakes.shp
- raster:
- a single point-like feature class - facility.grd
- road linework - roadsmajor.grd
Buffers
Method
- open GIS application
- add shapefile or raster layer to the map view
- zoom to the extent of the layer
- select buffer geoprocessing tool
- enter required parameters and options:
- input layer - the layer that the buffer operation will be applied to
- output layer - the new file that will be created and include the buffer features.
- distance - the distance from the input features that the buffer will be created at
- options - including the option to dissolve the resulting features by merging the buffer features together instead of retaining the individual buffer lines of overlapping buffer perimeters.
Exercise using QGIS
- open QGIS
- Load the data layer. Using menus at top of screen select LAYER -> Add Vector Layer
- Press Browse button
- Navigate to the folder holding the sample datasets and select busstopsall.shp and press Open button
- QGIS will automatically zoom to the extent of the bus stop features
- Run the buffer process from the menu: TOOLS -> Geoprocessing Tools -> Buffer(s)
- Set the Input vector layer to busstopsall
- Enter Buffer distance of 20. This will be 20 metres.
- Set the Output shapefile by pressing Browse button. Navigate to the data folder and enter the new filename as busstops_20m_buffer.shp. Press Save button to select that filename.
- Press OK button to run the process.
- After running, the system asks Would you like to add the new layer to the TOC? select Yes and the resulting shapefile will be added as a layer in your map view.
- Buffer(s) window remains open. Press Close to close the window.