Working with Raster Data; Georeferencing

Preparing Spatial & Tabular Data

Working with XY coordinate data; Mapping of Disease

Mapping Multiple Indicators

Mapping Program Coverage

Proximity Analysis; Buffers

Georeferencing means to associate something with locations in physical space

In GIS, it is the process of associating a physical map, or a raster image of a map, with spatial locations (coordinates) so that the raster data can be viewed, queried, and analyzed with other geographic data, or used to create geographic data.

Under this topic, we shall work on;

• Google Earth web
• Georeference an image in QGIS

Search for an area of interest in Google Earth

Create control points and save as a .kml file

Launch QGIS

In QGIS, georeferencing is accomplished using an external plugin called Georeferencer

In order to activate the Georeferencer plugin, select Plugins > Manage and Install Plugins from the QGIS main menu

Close the Plugins window

To open the Georeferencer tool, click on the main menu and select Raster > Georeferencer

Add the ungeoreferenced image

Process the data in a format that can be used in QGIS

Import the data into QGIS

Join (link) the data to administrative boundaries

Map population variation using the most and least method

Choose a classification scheme

Present results in a QGIS map layout

• Launch QGIS and create a new project
• Load county boundaries
• Explore the non-spatial features in attribute table
• Convert Excel file to .csv & load CSV file in QGIS
• Link non-geographic data with geographic data - QGIS Processing Toolbox
• Search for Join Attribute Tables tool

Create a choropleth map of feature (numeric data) variance

• Use the newly created dataset after the join
• Choose classification scheme; Natural breaks, Quantile, Equal Interval & Standard Deviation
• Click on Fill and select Transparent fill
• Click on Border to change the color of the border outline

Spatial information is communicated to external audiences either in the form of printed or digital maps.Additional data may be required

• Map elements; title, legend, scale, North arrow, & attributions

To create a map, click on the Print Composer button on the main menu.

Add X,Y coordinate data

Change coordinate systems

Perform spatial joins with summary statistics

Dissolve data

This is achieved by displaying one variable as a choropleth map and the second variable as a chart or diagram

• Create polygon centroids
• Create a choropleth map using one variable
• Symbolize the centroids using proportional symbols >> text diagrams - Set the Size of the symbol to zero to avoid superimposed symbols

Map program data using proportional symbols

Determining catchment areas or the geographic area covered by a facility or programs

Understanding all of the intervention points within a defined geographic area allows program planners to improve allocative efficiency and reduce duplication of efforts

• Vector > Geoprecessing Tools > Buffer
• Vector > Geoprecessing Tools > Intersect