Previous posts have referred to some of the software we have been using on the project. So, we will explain a little bit about this software in a series of blogs dealing with the packages we use for different aspects of the project. The first of these is on ArcGIS and other PC based software we use for mapping.
ArcGIS is the main software package we use on the project, and particularly the ArcView and ArcCatalog components; we also make use of Quantum GIS (QGIS), GNU Manipulation Program (GIMP) and Google Earth.
As the project uses GIS to arrange and orient various kinds of data geographically, ArcView is the component we use the most. ArcView allows us to display different layers representing different types of data. It is crucial in planning and implementing the survey as it gives us access to all the relevant data for an area of interest and will allow us to analyse those data when the project has finished. These data (layers) consist of mine locations, geological formations, topographical maps etc.
In addition to ArcView, we have been using ArcCatalog to create blank shapefiles (A shapefile is a file format created by Environmental Systems Research Institute (ESRI) to store location data in vector format, i.e. polygons, polylines and points, along with attribute information). Point files are single locations and consist of X and Y, and sometimes Z, co-ordinates, along with space for any additional data we may want to record such as an observation or a type of feature. Polygon files consist of points and lines joining them together along with the information defining how they relate to each other. They are frequently used to record large features and because they are complete shapes, whether regular or irregular, once they have been drawn we can calculate the area they cover. This is particularly helpful when trying to determine the size of a site or a feature. We can also add relevant information to the polygon files in the same way that we can with point files.
We can also use ArcGIS to create a link between our maps and our database of sites. These sites can then be displayed in their geographical location with all the information we have recorded about them. This will be covered in more detail in a later blog post.
For map preparation, mainly cutting out relevant map features (e.g., the area of a geological formation) and changing the file format, we have been using the GNU Image Manipulation Program (GIMP) on a MacBook Pro, because the use of a mouse and a larger screen is much more effective than the pen and touch input on the tablet PC.
We have been using QGIS (a free, and highly recommended, GIS package) predominantly for converting file types. As it is an open source programme it offers a larger number of possible file extensions for conversion without the need for expensive extensions. This has proved especially beneficial with the final programme we use, Google Earth.
We have used Google Earth in a variety of ways. The shapefiles produced in ArcGIS for the geological formations and the mining locations have been converted to the .kml format that can be opened in Google Earth. This is extremely helpful when communicating with colleagues and other interested individuals who do not have access to a GIS package. Secondly it has assisted in pre-planning the areas to visit through zooming in close to the earth’s surface and establishing whether features of the lime mines we have plotted, and other relevant geography, can be visualised. It may also provide an excellent platform for further dissemination of results in the future.
Now that we have covered ArcGIS and our other mapping programs, the next blog in this series will tackle ArcPad.
– A Reid