GIS Matters: Something for Nothing October 24, 2010Posted by Bahadir Sahin in English, Haber (News).
Tags: ESRI's ArcGIS Explorer, GIS technology, Google Earth
This article compares several free GIS software programs related to types of data management and map production activities of interest to the land surveyor. The list is not comprehensive; I simply chose to test and compare the software that is easy to find on the Internet, readily available, easy to download, and simple to install. While I have undoubtedly probably left out somebody’s pet program, my mission here is not to root out the deeply hidden gems on the Internet, but to inform readers of the advantages of the applications that are easy to find. The primary limiting factor in my selection is that the software must be completely free of charge to download and run. I did not test any free-trial software that limits the duration of use, or the number of files one can load.
The four I tested are ESRI’s ArcGIS Explorer, DIVA-GIS, Google’s Google Earth, and Quantum GIS. There were a few other free GIS tools that I downloaded, installed, and tried to add data to, that were too complicated to set up to load existing datasets, or required too much command line typing with arcane syntax to be easy and quick to use. In this era of software, my mantra is keep it simple. If the software is simple to use and understand and provides a few essential functions, then people will readily adopt it. Google Earth for example, meets those criteria, and that is why it became so popular so quickly.
Software that is difficult to learn or that takes a long time to learn must offer something very compelling to motivate people to invest the time and effort, and usually the money for training to become competent with it. In this series, our focus is on introductory instruction in basic GIS tasks to help the surveyor take advantage of the GIS technology. As you become more adept with GIS and your understanding of the capabilities and power of GIS increase, you may then want to do sophisticated data management, editing, and analysis. When you get to that point, you will be ready and perhaps eager to invest in better software and to get the training to learn to use it.
The perspective that I used for testing was that of surveyor creating a map of a property for a client using free GIS software and GIS data that may be available locally. The deliverable products include: a paper map, a PowerPoint slide or two showing the property location in general, the property boundary with annotated features on an aerial photography base, a zoning map, and other relevant data.
The functions that I considered reasonably necessary to accomplish this include: the integration of vector data, geo-registered imagery, custom symbology, custom annotation, professional quality map cartography, and the ability to copy the map to the Windows clipboard and then paste that into PowerPoint.
Some of the operations and functions that are helpful to get to that point include: the ability to import an AutoCAD DWG or DXF, or an ASCII file of points, the ability to zoom and pan around the map, the ability to annotate a map layout and insert map elements (such as north arrow, scale, legend, custom title, etc.), and the ability to search for specific information or a particular location.
Other helpful functions include some GPS operations such as the ability to connect to a GPS stream or import GPS data. The ability to export data to GPS is helpful for taking the GIS data into the field.
I also listed a few functions that one might want to perform such as editing the geometry or attributes of a layer, and some types of analysis such as buffers and network analysis.
I used the following existing data for the testing because I felt these were representative datasets with regard to content and format:
• Parcels (vector polygon shapefile)
• Subdivision boundaries (vector polygon shapefile)
• Aerial photography (digital orthoimagery)
• Digital elevation model (raster elevation data)
• Zoning (vector polygon shapefile)
• Roads (vector polygon shapefile)
• Building footprints (vector polygon shapefile)
• Well location (GPX file from handheld GPS)
• Contours (vector AutoCAD dwg or shapefile)