More than maps

Maps are the fundamental, primary output of geographical information systems (GIS). This is not surprising, considering that the unique characteristic of GIS is the ability to perform spatial analysis. The use of maps to display the results of spatial analysis seems to be a logical and appropriate means. It is, however, important to note that maps are not the only output of GIS, and there are other forms of displaying the results, some of which display things that a map can not. These non-cartographic forms of GIS output can be alternative or supplementary to hard-copy or digital maps.

This post presents a set of notes on different types of output, including: case examples where cartographic output is not sufficient for specific needs, and a discussion on alternatives to simple, static maps. This is followed by an investigation of some examples of non-cartographic GIS output.

The specific uses of cartographic outputs

Maps are visual representations of the real world or of possible situations in the area represented. As cartographic outputs, hard-copy maps are a “flattened” image of multiple data layers. The same is true for digital image files. For this reason, the producer of the map usually designs it so that relevant data layers are visible, so that the viewer of the map can see a visual representation of something specific. In this map, for example, the producer included some transport layers, land use layers, water features, and labels, as well as a points layer showing the location of the car dealership.

In the final product, however, it is not possible to work with the individual layers that were used in producing the map. For this reason, a map is limited in its application, and it serves a specific function. There is no option for a user to remove undesired layers or add extra data layers.

Maps are very specific in their purpose, and this may lead to the perception that they oversimplify phenomena (Joyce, 2009:837). For example, the map in this example would be inadequate for precise scientific calculations, as it shows a general trend at a small scale. There are also limits in that the image does not supply any metadata, including the date of the map.

Dynamic and Interactive Maps

In addition to static maps such as these, it is possible to produce maps that show changes in the data over time. While this can be observed by comparing multiple static maps side by side, there is a distinct output which is different from the general concept of a map as an image on paper or screen. This output of GIS (where time is included) takes the form of animated maps. This type of mapping is useful for showing things such as changing weather patterns, where the change is important to help with predictions.

There are, however, limitations of maps. They can appear intimidating and confusing (Joyce, 2009:836), especially when not designed well. Maps are also culturally-specific, and bound by standards which may not be logical to everyone. A good example is the simple tradition and standard that north is “up” – a presumed standard which is challenged by McArthur’s “Corrective Map of the World” produced in 1979 (Flourish, 2008). Furthermore, there is a limit to which maps can be used for analysis and decisionmaking, as some information might be sacrificed for the sake of producing a simpler map. In these cases, interactive published maps provide greater functionality for users, and non-cartographic outputs can be individually selected and used. Even so, there are cases when something entirely noncartographic is required. Alternative ways of data presentation are sometimes necessary to catch and hold viewers’ attention, and multimedia or multi-dimensional data presentation (example) is a possible solution for cases where normal maps are less effective.

Non-cartographic output

Maps may be the fundamental output of GIS, but the value non-cartographic must not be overlooked. It is possible to consider these alternative outputs in two categories: visual (or graphic) and non-visual (or statistical). A third category may be observed between the two, though it is not mutually exclusive, as will be shown below.

Visual Outputs

Videos and visualisations are products of a GIS that are used for presentations and communication of data. These media may be used when the audience does not respond well to static images or facts and figures. When using these visual outputs, there is sometimes a need for accompanying tables or explanations (spoken or written narrative). Multidimensional media provide a virtual experience for an audience which is not able to access a natural environment directly, and this is true for future modeling too, where a landscape or development is presented virtually, before it exists in reality.

Whether these visual outputs are 3D digital elevation models, moving diagrams, 3D flythroughs or simulations (example), they are all powerful visual representations of geospatial and attribute information. There is also potential for the inclusion of realtime dynamic change in visualisations, to truly explore the time-aspect of geography – Torrens’ website (2009) shows possible applications of this. Another form of visual GIS output is a chart or graph – used to display relationships between attribute data or geographical relationships, these are graphical representations of the statistical, non-visual outputs of GIS.

Non-visual Outputs

Non-visual outputs of GIS include tables, numbers, bearings, areas, text – essentially all of the answers to geographical questions. Usually, GIS is used to analyse spatial and non-spatial data for a particular purpose of informing decision-makers. The way that the system contributes this knowledge is by answering questions such as “How far is x from y?”, “Where is the closest water source for this school?”, “How do I get from New York to California?” or “What is the direction from A to B?”. It is possible to use GIS to answer all geographical questions, if there is sufficient data.

Non-visual outputs are produced from queries of attribute data and spatial analysis. While maps are used to display the information, the reported measurements and numbers are more accurate than a measurement taken on a paper map and converted using the scalebar. The answers to the geographical questions are statistical or linguistic – “29.449m”, “at the railway station”, “Head southwest on 7th Avenue…”, “147.9 degrees”.

Outputs for Input

Somewhere between visual and non-visual outputs, we find the outputs which are spatial, yet are made for further use and analysis.  All of the outputs from GIS tools in the ArcToolbox are examples of these. Each tool or model processes data and creates output. When using ArcMAP, outputs can either be added to the data view, or they can be saved as files for use elsewhere.

The new files which are created or exported (for example, .dwg, .kml, .shp, .lyr, .mdb), can maintain their spatial properties and attribute data – a good example is CAD output, where features can be exported as precise 2D or 3D drawings. The design strong design tools in programmes such as AutoCAD mean that 2D/3D models can be designed in CAD format and then brought back to ArcGIS for topological and geographical analysis. Non-spatial data can also be outputted, in the form of tables and databases which are used for input in other processes.

Conclusion

It is important that the variety of outputs from a GIS are remembered, because a narrow view will limit the capacity of the system. While maps have powerful applications, this essay has shown that there are many other forms of output, each of which provides greater usability of data. A synthesis of the different outputs for presentation or for empirical analysis will make better use of the GIS and will strengthen the activities that rely on the outputs of GIS.

References:

EagleGlobe. 2009. Screenshots. [Online], Available: http://www.eagleglobesoftware.com/screenshots.htm [13/08/09].

Flourish. 2008. The Upsidedown Map Page. [Online], Available: http://flourish.org/upsidedownmap/ [13/08/09].

Google Maps. 2009. New York, NY to California. [Online], Available: http://maps.google.com [13/08/09].

Heart Health Inc. 2007. Heart Disease in America. [Online], Available: http://www.hearthealthintl.com/heart_disease.html [04/08/09].

Kelfords Ford & Mazda, 2008. Map to Kelfords. [Online], Available: http://www.kelfords.co.za/contact.htm [04/08/09].

Joyce K. 2009. ‘‘To me it’s just another tool to help understand the evidence’’: Public health decision-makers’ perceptions of the value of geographical information systems (GIS). Health & Place 15:831-840.

Torrens, P.M. 2009. Geosimulation. [Online], Available: http://www.geosimulation.org/geosim/3d.htm [13/08/09].

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