Overview of Geospatial/Geodetic Engineering

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'''''Lead Author: ''' Ulrich Lenk''

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This article forms part of the Overview of Geospatial/Geodetic Engineering knowledge area. It provides a broad introduction into the overall topic of related applications in order to make the reader aware where those technologies are actually used in Systems and Systems of Systems.

===GIS and Geospatial Applications ===

Although the overall intention of this article is to provide an overview into geospatial technologies, it is not and it cannot be the intention to provide here an exhaustive introduction into the wide field of GIS and its direct and indirect applications. Perhaps the most comprehensive recent standard textbooks on GIS are (Longley et al. 2015) and (Kresse and Danko 2012) but beyond these texts, there are reams of other textbooks on GIS and respective spatial data capture procedures (surveying/photogrammetry/remote sensing) and management applications available. (Tomlinson 2019) and (Peters 2012; see also the online successor version of this text book: [System Design Strategies http://www.wiki.gis.com/wiki/index.php/System_Design_Strategies]) provide valuable insights into aspects of how to set up a GIS system. While (Tomlinson 2019) looks more at the management perspective and processes of implementing a GIS, (Peters 2012) considers the technical aspects more.

Domain-specific GIS applications are also documented by numerous textbooks, including:  agriculture and forestry, insurance economics and risk analysis, simulation and environmental impact analysis, hydrology, archaeology, ecology, crime investigation and forensics, disaster management and first responders, marketing, municipalities and cadaster, land administration and urban planning, utility sectors, telecommunications, smart cities and last but not least, military applications. The latter include Command and Control (C2) systems, or are even extended in Command, Control, Communications, Computers Intelligence, Surveillance and Reconnaissance (C4ISR) systems. Generally speaking, wherever data, i.e. information to events that occur, is displayed, processed and/or analyzed in a geospatial context, there is GIS technology involved, whether the user interface is based on a web interface, a desktop client, or a mobile device such as smartphones and tablet computers. To provide for visualization of this data, a spatial context for orientation, geospatial data like digital topographic maps, or geospatial imagery, digital elevation model, etc. is needed. Beyond this classical geospatial data, other types of data are also often used, like meteorological and other environmental data.

It is worth mentioning that interoperability is of major concern within the realm of geospatial technology. The [Open Geospatial Consortium http://www.opengeospatial.org/](OGC) is probably the most relevant organization that deals with GIS and sensor systems interoperability. The OGC has published a dedicated set of [interface specification standards http://www.opengeospatial.org/standards] on their topics.

===Positioning, Navigation and Timing===

While the above description of geospatial technology focused mostly on aspects of stationary, i.e. non-moving geospatial data, this section is mainly concerned with the localization of moving objects in space and applications that are derived from this, like navigation, monitoring, and tracking of objects (while the latter is already done in combination with GIS, see above), etc. The basic operations needed for this purpose are positioning and navigation. Certainly the majority of people using smartphones are also using the various location based services (LBS) that are provided (in conjunction with GIS databases and services, such as Google Maps, a well-known online GIS application). As a consequence, positioning and navigation, which is mainly achieved with Global Navigation Satellite Systems (GNSS), became an ubiquitous and transparent technology in the last decade. Clearly the most relevant system in common use in the past has been the US Global Positioning System (GPS) since it was the first of its kind.  It is not the only one of its kind, as Russia developed a GNSS called GLONASS, Europe developed the Galileo system which is close to achieving full operating capability, and last but not least, China is working on the realization of its Beidhou GNSS. It is interesting to notice that GNSS are not only used for positioning and navigation. Since the range measurements conducted by GNSS are based on extremely accurate one-way travel times of signals, extremely accurate clocks in the satellites are a fundamental necessity in the systems. Time is transmitted by GNSS based on these clocks, and as a consequence of these commonly available time signals, they are also heavily used by systems as a time normal and service, e.g. for time wise synchronization of systems (and derived from this as well frequency normals are established). Consequently, these three services provided (mostly) by GNSS are put together into the abbreviation Positioning, Navigation and Timing (PNT). For details of satellite navigation cf. e.g. (Teunissen and Montenbruck 2017) or (Hofmann-Wellenhof et al. 2008), although, like for the domain of GIS, there are reams of textbooks available. While in this section the application of PNT focused on moving objects, GNSS technologies are also heavily used for the production of geospatial data, i.e. in surveying engineering, which is then used within GIS for display and analysis.

What is probably not quite familiar to the public is that many systems used in various different domains are nowadays relying on the availability of GPS/GNSS signals. It has been analyzed that the majority of national critical infrastructures are dependent on GNSS (Royal Academy of Engineering 2013; Wallischeck 2016) and thus the availability of open access to GNSS signals is nowadays considered as a critical infrastructure itself. Infrastructures and applications depending on GNSS include but may not be limited to transport (rail, road, aviation, marine, cycling, walking), agriculture, fisheries, law enforcement, highways management, services for vulnerable people, energy production and management, surveying, dredging, health services, financial services, information services, cartography, safety monitoring, scientific and environmental studies, search and rescue (e.g. as given with the Global Maritime Distress and Safety System, GMDSS), telecommunications, tracking vehicles and valuable or hazardous cargoes, and quantum cryptography (Royal Academy of Engineering 2013).

===Geodesy and Geodetic Engineering for Providing the Frames for All Spatial Applications===

The above sections are purely application oriented. However, at the basic level of modeling, all numerical (coordinate-wise) descriptions of natural and man-made (mobile) objects, including the ones in space, i.e. satellites, need to be, in simple words, referenced to a coordinate system. It may be a local (moving) engineering coordinate system, a national coordinate system, a regional coordinate system, or even a world coordinate system, e.g. that given by the well-known World Geodetic System 1984 (National Imagery and Mapping Agency 2004), which is the coordinate reference system in which GPS works. Whereas horizontal coordinates are fairly straightforward since they are mainly based on mathematical assumptions with little input from geophysics (the localization of the rotation axis of the Earth), the third dimension is mostly treated differently since heights are often related to a mean sea level (MSL) surface, which is dependent on the (irregular!) distribution of masses on Earth and thus on their physical properties. The typical surface used for referencing heights is the so-called geoid which may be approximated by MSL. Beyond these Earth related aspects, however, there are also celestial coordinate systems in place, and coordinate systems on other celestial bodies. A typical standard textbook on geodesy is given by (Torge and Müller 2012). Thus, geodetic engineering with its sub-disciplines of physical and mathematical geodesy together with its partner engineering disciplines provides fundamental frames to the public for various different applications in science and technology including Systems of Systems.

===Visualizing Spatial Data with Map Projections and Cartography===

At the end of day, since human beings rely heavily on visual depictions rather than on verbal descriptions, the fairly complicated surface of the Earth with its features on it typically needs to be “pressed” onto a flat screen (even when it is a 3-dimensional perspective view on a 2D screen) which, depending on the display scale, cannot be achieved without certain or even significant distortions of the shape of the objects. Mathematical geodesy and map projections based on differential geometry provide the basics to achieve these goals, cf. e.g. (Grafararend et al. 2014). By carefully selecting an appropriate map projection, different characteristics of (relations of) land masses and applications can be emphasized. One example may be the difference between the classical Mercator projection that is used for nautical charts from the equator up to medium latitudes, and the Stereographic projection that is often used in aeronautics since the shortest distance between two locations is there a straight line. For the Mercator projection, a straight line is the line of constant bearing which eases the use of a magnetic compass for steering a vessel (neglecting the variations of magnetic declination on Earth), and the shortest distance between two points on the Earth’s surface(the geodesic) is a curved line on the chart whose curve is bent towards the pole of the respective hemisphere.

As visualization of spatial data is a fundamental functionality of GIS, respective map projection modules are always included in GIS software packages. Beyond these purely projection related aspects of visualization of spatial data, cartography provides rules and procedures for what to display and how to visualize geodata, abstracted as symbols, lines, areas, what color and styles are to be applied to the graphical elements in a map, how to relate these to each other on a screen (or a paper map), how to generalize them when the scale of display is changed etc. (Kraak and Ormeling 2020).

==Geospatial Aspects in INCOSE Cross-Cutting Systems Engineering Methods and Specialty Engineering Activities==

Systems Engineering and “architecture definition activities include optimization to obtain a balance among architectural characteristics and acceptable risks. Certain analyses such as performance, efficiency, maintainability, and cost are required to get sufficient data that characterize the global or detailed behavior of the candidate architectures with respect to the stakeholder and system requirements” (INCOSE 2015). The set of respective activities that is necessary to analyse these aspects are the so-called “Specialty Engineering” activities in (INCOSE 2015), and the list of related activities is as follows:

* Affordability/Cost-Effectiveness/Life Cycle Cost Analysis;

* Electromagnetic Compatibility*Environmental Engineering / Impact Analysis;

* Interoperability Analysis;

* Logistics Engineering;

* Manufacturing and Producibility Analysis;

* Mass Properties Engineering;

* Reliability, Availability, and Maintainability;

* Resilience Engineering;

* System Safety Engineering;

* System Security Engineering;

* Training Needs Analysis;

* Usability Analysis/Human Systems Integration; and

*Value Engineering.

Looking at these dedicated Specialty Engineering activities from (INCOSE 2015) and at the plethora of geodetic and geospatial technologies and services (cf. Sec. II) available, at least the following subset of Specialty Engineering activities can benefit in particular from Geospatial Engineering activities or need to include respective geospatial considerations.

*Environmental Engineering/Impact Analysis

*Interoperability Analysis

*Logistics Engineering

*Reliability, Availability, and Maintainability

*Resilience Engineering

*System Safety Engineering

*Usability Analysis/Human Systems Integration

Also, INCOSE lists in (INCOSE 2015) a set of methods so called Cross-Cutting Systems Engineering Methods, amongst which “Modeling and Simulation” is described which is also heavily related to geospatial and GIS technology when these activities take place somewhere in the landscape. The next section will shed more light on potential geospatial contributions to these dedicated activities.

==References==

===Primary References===

Grafarend, E.W., R.-J. You, and R. Syffus. 2014. ''[[Map Projections: Cartographic Information Systems]]'', (2nd edition). Heidelberg, New Yort, Dordrecht, London: Springer.

Hofmann-Wellenhof, B., H. Lichtenegger, and E. Wasle. 2008. ''[[GNSS - Global Navigation Satellite Systems.]]'' Wien: Springer-Verlag.

Kraak, M.-J. and F. J. Ormeling. 2020. ''[[Cartography: Visualization of Geospatial Data]]'', (4th edition). London, New York: Taylor & Francis.

Kresse, W. and D.M. Danko (Eds.). 2012. ''[[Springer Handbook of Geographic Information.]]'' Berlin, Heidelberg: Springer.

Longley, P.A., M.F. Goodchild, D.J. Maguire, and D.W. Rhind. 2015. ''[[Geographic Information Science and Systems]]'', (4th edition). New York, Chichester, Weinheim: John Wiley & Sons, Inc.

Peters, D. 2012. ''[[Building a GIS: Geographic Information System Planning for Managers]]'', (2nd edition). Redlands, CA: Esri Press.

Teunissen, P. and O. Montenbruck (Eds.). 2017. ''[[Springer Handbook of Global Navigation Satellite Systems.]]'' Switzerland: Springer International Publishing.

Tomlinson, R.F. 2019. ''[[Thinking About GIS: Geographic Information System Planning for Managers.]]'', (5th edition). Redlands, CA: Esri Press.

Torge, W. and J. Müller. 2012. ''[[Geodesy. ]]'' Berlin: De Gruyter.

===Works Cited===

Hahmann, S. and D. Burghardt. 2013. ''[[How much information is geospatially referenced? Networks and cognition. ]]'' International Journal of Geographical Information Science 27(6):1171-1189. DOI: 10.1080/13658816.2012.743664.

INCOSE. 2015. ''[[INCOSE Systems Engineering Handbook|Systems Engineering Handbook]]: A Guide for System Life Cycle Processes and Activities'', (4th edition). San Diego, CA, USA: International Council on Systems Engineering (INCOSE), INCOSE-TP-2003-002-04.

National Imagery and Mapping Agency. 2004. ''[[World Geodetic System 1984.]]'' (3rd edition, including Amendment 1 and 2). Department of Defense. Technical Report TR8350.2.

Royal Academy of Engineering. 2013. ''[[Extreme space weather: impacts on engineered systems and infrastructure.]]'' London, UK, Royal Academy of Engineering.

Wallischeck, E. 2016. ''[[GPS Dependencies in the Transportation Sector.]]'' Cambridge, MA: U.S. Department of Transportation, Office of the Assistant Secretary for Research and Technology, John A Volpe National Transportation Systems Center.

===Additional References===

Freeden,W. and M.Z. Nashed (Eds.). 2018. ''[[Handbook of Mathematical Geodesy: Functional Analytic and Potential Theoretic Methods. ]]''. Basel: Birkhäuser.

Meyer, Th.H. 2018. ''[[Introduction to Geometrical and Physical Geodesy: Foundations of Geomatics.]]'' Redlands, CA: Esri Press.

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