Practical Manual - Malareo

Acquiring Spatial Data
There are numerous types of data available and the sources of these data are varied. The quickest and
easiest source of data is the internet and a fair number of the coverages (layers) you are using come
from the internet. However data often has restrictions associated with it, be that in terms of distribution
or utilization. Often free data is made available for education and research but not for profit. Also as the
data is free there is no guarantee of accuracy or content. This needs to be taken into account. A highly
accurate source of data is usually government departments especially the Surveyor General of a
country. Data providers can also be employed to acquire data, be that from aerial photography or
individual GPS surveys or projects. How you source data is dependant on the needs of the project and
the budgets available.
GIS Data can be acquired from various sources or using various means. These include government
departments, Data vendors, the internet, from a GPS, on screen digitizing, importing images and georeferencing
them and importing CAD diagrams and converting formats.
A number of sources of data include:
Diva GIS http://www.diva-gis.org/gdata
GeoSpatial Portal http://www.opengeospatial.org/
Free Maplibray http://www.maplibrary.org/
The Protected Planet (Conservation Areas) http://protectedplanet.net/
The USGS http://glovis.usgs.gov/
Therea re literally dozens of sites available for downloading data, each with their own requirements.
Go to the DIVA GIS site on your browser and Download the Administrative boundaries for South Africa
(if you do not have an internet connection these are available in your data folder.
Most data is in a zipped format (8.zip or *.rar) and will need to be extracted into a usable data type or
format. In most cases this will ultimately be as shape files.
Data Formats
There are numerous data formats that are used by different GIS systems. These include but are not
limited to:
ESRI Shape files (*.shp)
ESRI Personal Geodatabase (*.mdb)
ArcInfo Ascii (*.e00)
MapInfo (*.tab)
Microstation (*.dgn)
Comma Delineated text (*.csv)
QGIS for Malaria Page 17