Geodesy

Abstract

Geodesy, starting as a scientific discipline exploring the size of the earth in the eighteenth century, soon produced the basis of modern land tax systems and enabled the institution of individual property rights in real estate, a backbone of the constitutional order. Geodesy stimulated the development of the modern state by data collection and land management methods. The satellite techniques and the advancement and the expansion of the sensor technology based upon the theoretical mastery of the space in methods and incoming data made the geodesy and its professionals effective in the public management and the economy. Geodesy as an economic sector producing and managing geo-information is deeply woven in different disciplines of science, public administration, and economy but recognizable by its methods and results.

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Definition

Geodesy is a discipline in science, government, land management, and industry. It addresses the shape and the shape near earth, the national government of land, the land management, and real estate property.

Geodesy: Reference Frame for the Earth

Geodesy explains the knowledge about the shape and shape near earth. It comprises specific methods which are useful to analyze tectonic movements but also to manage countries, land, and plots.

It needed more than two millennia to go back to the anthropocentric worldview, but then in the seventeenth and more in the eighteenth century, the technical progress blessed Europe with telescope and a growth of mathematics. The conquest of the continents brought new knowledge about the earth. The question for the right dimension and the shape of the earth moved into the center of the scientific research. Since the angular measurement succeeded to feature a considerable accuracy, the measurement of length was the biggest problem for 200 years (Torge 2009).

The geodetic science succeeded to improve the determination of the dimension of the earth by long triangulation chains along the several meridians on the northern and southern hemisphere. The determination of the International Meter was more or less a by-product. On the basis of this and the expansive surveying methods, the European governments had new tools to manage the countries in a just way. The national economies were able to flower out in an unimagined way.

This deconvolution was a precondition for the preeminence of the European nations in the world. The implemented techniques gave distinction to the scientific specialization under the name of “geodesy.” The application of the methods in small-scale areas of about less than 1 km², in which the spatial discrepancies are negligible to small for a sufficient accuracy (Kahmen 2005), coined the profession of the “geometer,” later referred to as “surveying engineer”.

Whereas the systems of base mapping – big or small – got a national character, because the military security asked for that, geodetic technology always had to be international. Only with international cooperation and in addition with the cooperation with the neighbored geosciences, the possibility evolved for tackling the phenomenon “earth” (Ledersteger 1969) (Fig. 1). And all the more so when the scientific progress bestowed methods on us which could determine the gravity field, the rotation of the earth, the movements of the continents, and the mass movements of the earth’s interior (Fig. 2).

Fig. 1

The earth as a mathematical abstraction

Fig. 2

Study object earth

To determine the geodetic frame for national control networks was always one of the most important tasks of geodesy. But international cooperation on this became more and more successful (Schuster 2005). The International Earth Rotation and Reference Systems Service (IERS) maintains the International Terrestrial Reference System (ITRS), which describes the procedures for creating reference frames suitable for use with measurements on or near the earth’s surface. This International Terrestrial Reference Frame consists of the high-precision coordinates and velocities of about 400 globally distributed stations (Fig. 3). These three-dimensional Cartesian coordinates and velocities define the positions and the plate tectonic movement, the ITRS.

Fig. 3

The shape of the earth – under control (Courtesy to Prof. Harald Schuh, GFZ Potsdam)

The ITRF points are part of the European ETRF and the regional networks like the German control net, called DREF, or even networks of lower order under national control; they form together the international frame of high precision. It makes us measure the dislocations of the 19 tectonic plates (Fig. 4), (Sella et al. 2011).

Fig. 4

Tectonic plate dislocations (ITRS Combination Centre at DGFI-TUM 2014) https://www.dgfi.tum.de/international-services/itrs-combination-centre/

From the beginning astronomical geodesy was necessary to locate the datum of every triangulation net on the ellipsoid. Soon satellite orbits were calculated, and the theoretical earth tides were compared with those measured by gravimeters and horizontal pendulums. Insofar geodesy was prepared for the huge next step, the use of the earth near satellites. Up to that time, the meteorological conditions only were disruptive elements for the optical determination of lengths and heights, but then the meteorological surroundings more and more came into view with the higher accuracy of all results.

Geodetic measures are deeply influenced by the shift of masses (Fig. 5) between tectonic plates and the respective interdependence with solid earth and oceans, atmosphere, hydrosphere, cryosphere, biosphere, and asthenosphere (universe). The scientific picture of the earth changed from the spherical shape of the spheroid to the ellipsoid, further to the geoid. In addition the geodetic science taught us that our earth is in an ongoing process of change.

Fig. 5

Opposing forcing affecting the earth (Vienna University of Technology)

Today, the highly accurate geodetic frames ITRF and ETRF and the national frames like DREF are combined, even merged. Everybody can locate himself or move in that system. His measurements – mounted in the net – are now worldwide identifiable for about better than 1 [cm] (Seitz et al. 2016). Unlike earlier times the surveying engineer can detect, if the sunspot activity is strong and the magnetic field is jammed. This he has to take care of when performing his measurements.

Individual Property Rights

During the colonization of earth, people became increasingly aware that fruitful land is a scarce resource. It is worth to settle there and to assert the ground. On those places, where people met for trade and change, regulations were accepted for the peaceful way of dealing with each other. Not mentioning the tremendous achievements of the Romans in surveying of their empire, the geodesy steps into the limelight of history, when the harvest tax systematically turned to ground tax. At the end of the eighteenth century, the science provided the technological possibility to expanse scalable maps over the country and to document securely the property borders (Fig. 6). Since that time a fair, area-based tax regime became possible. Tax cadastres became fashionable for modern states. Soon large-scale soil fertility evaluation systems for farmland were set up on these cadastres.

Fig. 6

Modern cadastral map, 1:1000

The systematization of the taxation (Fig. 7) and the spread over the countries took technically and politically nearly a century in Europe. But this installation provided the nations with safe funds (Fig. 8). The other side of the coin was that the citizen’s rights in their property were strengthened. Geodetic technique was weaved in the deploying civil system of justice. The civil code, the land register ordinance, and the official regulations for the property cadastre came to their heyday at the beginning of the twentieth century. The taxable value is a legal definition for private plots, operational premises, and farming or forestry property. It should be equivalent to the market value, but all over Europe, there is a great variety of tax procedures and level of taxation. In countries like the Netherlands and Sweden, the method of mass evaluation for the ground taxation is discussed. A lot of member states of the European Union are seeking for an easy and secure way for this taxation. The qualitative classification of the nations concerning just ground tax, secure property, and successful mortgaging is an unmistakable sign for the development of land management.

Fig. 7

Soil fertility valuation, 1:5000

Fig. 8

Soil fertility map, 1:2000

The development did not come to halt (beside the communistic part of the world). Legal and management principles changed with the development of the economy and its regulations. The improved cartography and copying techniques lead to further cadastres showing other attributes of parcels and their buildings (i.e., cadastre on public land charges or pollution suspicion cadastre, geothermal cadastre, ao). They influence the rights in land substantially.

The geodetic professionals working in private or public businesses managed the property cadastre and taxation in form of cadastre measurements and cadastre amendments and the evaluation of the ground (Schuster 1981).

In the nineteenth and twentieth century, the rural and urban land readjustment and the management of settlement became an important economic factor driven by geodetic professionals. With the measures of public authorities, the farmers succeeded to raise their crop yields substantially; the drift of the population to the cities was stopped. They succeeded to overcome the big streams of people into the industrial areas.

At least after the Second World War, they managed to integrate 12 million people into the West German population. Geodetic reallotment and evaluation measures were a significant part of the success.

Real Estate Economy

Geodesy is a basis for all real estate economy.

The upcoming time of geo-information opens new economic prospects and effective tools for the protection of our environment. The safe governmental documentation of properties and the loan capabilities (Kerl and Schuster 2003) provided the growing economy by capital generation. The results are reflected in a growing built-up space for industry and residence. Diverse forms of right or property were developed on the basis of the property register and cadastre. They developed their own business cycles. Geodetic services were part of this process of development, but managed mostly only the geometric relocation of the property borders. Slowly they supplied the growing demand of their clients in consulting concerning the more and more complex subject.

In the socialist countries, this development failed even if the geodetic basics and also services for mapping and the building regulations were still or even newly existing. Without the individual property in land, the economic shaping forces were lame. The real estate economy was no area of added value. After the political transformation in 1989, this form of economy on the basis of land quickly induced a takeoff. The authorities quickly transformed their character and got reformed. But with these events, the societal questions around land are not yet answered. The more developed a nation and its civil class is, the more sophisticated and dense is the wood of regulations based on land. This business life pushes the gross national product of a country immensely. But in that sphere, there is easily coming up the danger of non-genuine growth: economic blows and the growth of bureaucracy can jeopardize the national economy. Both emerge because of inappropriate regulations and misguided public work.

Geodesy is part of this economic process by its land management component, which expanded its methods and performance strongly in the second half of the twentieth century. The German federal building law (BauGB) and the federal land use order (BauNVO) together with the rapidly growing public law considerably influenced the methods of property evaluation and readjustment, which were used in the public and private part of the business life. Other developed countries have similar regulations.

The development of standard ground values and the installation of committees of expert valuers became an internationally acclaimed model for subduing the blows or deflation elements.

Since the Millennium not only the migration from country to town was noticeable but also the diminishing of an aging European population becomes apparent. The economic output of the house construction industry became much smaller and this happened as well in that part of the geodetic economy. On the other hand, the investments for the maintenance and renewal of the buildings pushed ahead by certain tax reductions and ecological regulations grew strongly. The industry sold their houses for workers by privatization, so the number of transactions swelled (Fig. 9). The people as economic actors wish to safeguard their property, and by that the economic transactions remained on a high level.

Fig. 9

Numbers of transactions – city of Duisburg

Foreign capital searched from 2005 to 2008 for investment opportunities. This pushed the price level especially in the European agglomeration zones. Geodetic services are involved in that part of the economy with evaluation of real estate, property consulting, and evaluation for mortgages.

These different types of propulsions let the transaction traffic remain on a high level, even if the development of new development in unbuilt areas was strongly reduced.

From both pictures (Figs. 9 and 10), you can deduce the economic importance of the real estate economy. In a city of 500.000 inhabitants happen to be concluded not more than about 4000 contracts per year, which means not more than about 8.000 contract parties. It is a small part of the town’s people to exchange a fortune of 500 Mio € up to 1 billion € per year. A number of 250–500 unbuilt plots with a transaction value of 50 to 80 Mio € changed the ownership. These plots are predominantly the basis of a development of the city further on.

Fig. 10

Cash flows of transactions – city of Duisburg

The number of contracts for developed, built plots is about 1.500; their value balances around 500 Mio €.

1200 to 1500 contracts are concluded concerning residence and part ownership with a value of about 60 Mio €.

Behind the curtain of this development, over the years there are a lot of different influences changing from year to year. The last ascent of values is reckoned to be based on the fear of people for their financial assets, not coming from a bigger need on the renter’s side.

From “concrete gold” people expect to gain the best long-term maintenance of value.

Market economy is a contract economy. The exchange of property only means the top of the economic contracts in the real estate economy. The broad base of contracts is the renting contracts.

An exchange by contract of about one billion € releases work for the service institutions register and cadastral office, notary, broker, and public appointed surveyor of about 50 Mio €. The transaction tax for the community as well costs the parties 5% which means about 50 Mio €.

Geodetic Technology

Geodetic technology is more productive than ever in history (Schuster 1985). The number of sensors and items grew enormously: satellites for GNSS, altimetry, gravity field missions, side-looking airborne radar (SLAR) or synthetic aperture radar (SAR), and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) (Fig. 11). Not to forget the equipment for atmospheric exploration, the Very Long Baseline Interferometry (VLBI) and the tide gauges or even complex systems like tsunami detectors are all being used in the low and medium earth orbits.

Fig. 11

Geodetic technology in the earth near space (Courtesy to Prof. Harald Schuh, GFZ Potsdam)

With remote sensing a new geodetic technique came up for evaluation of the satellite photography, laser and radar surveys.

New sensor technology presents a variety of technical devices with regional impact like surveying planes or helicopters, steered by IMUs (inertial measurement units) with a variety of aircraft cameras and lasers. Most of the sensors built have a local impact: GNSS Rovers for dm or cm – accuracy, combined positioning and sensor systems for vehicle fleets or personal tracking as well as tachymeters as total stations and laser scanners of different type (Fig. 12).

Fig. 12

Geodetic sensors with local perimeter

In the metrological scale, we find many robotics and high-precision measuring instruments (laser tracker ao), necessary for 3D measurements, and in-house laser systems in a local reference system.

The geodetic methods are directed upon maps and scientific results, but also upon data pools consisting of maps and alphanumerical information like property cadastre and surveying and engineering geodesy. They are used for the control of the building process. There is a big variety of procedures, products, and results. As far as they are based on measurements, they are to be distinguished by an implicit or explicit stochastic. For long the maps developed to graphic interactive systems (GIS). The orthophoto as an automatically generated aerial scalable photo is a worldwide proven and successful product.

Unexpectedly the unmanned aerial vehicle (UAV) or shortly drone started its triumphal march into the geodetic technology: equipped with cameras of most different quality or even small lasers, they catch up the objects in the space near to the surface (Haala and Schwieger 2017). The point clouds produced lead to new economic useful results, i.e., for monitoring, quantity or mass calculation, urban models of higher level of detail (LOD), roof landscapes as orthophotos (Fig. 13), a geodetic base for the building information modeling (BIM), or disaster control. Powerful geodetic software modulates the transformation of the point clouds.

Fig. 13

Roof landscape as an orthophoto (acc. <±1 mm) captured by UAV

Geodetic laser scan or even laser slam methods (without any fixed standpoint) capture new fields of application spirited up by the revolutionary building information models, which need and are able to process Big Data results during the construction process (Fig. 14).

Fig. 14

Building captured by laser slam – base for BIM

Parallel to mechanical engineering, the quick comparison between the actual status of a construction in progress can be realized with an authentic point cloud by laser slam, which is called “trusted living point cloud” (Fig. 15).

Fig. 15

Trusted living point cloud

The actual expansion of the sensor technology and the velocity of the data capturing enable the geodesy to do its bit for the “smart construction site.” The cross-linking of sensors, devices, machines, and finally the workforces is beginning (Fig. 16). The result is a seamless communication between sensors and server over the Internet. The sensors deliver the current necessary information for workforce and fleet management and support the accounting of the site’s activities. Complex algorithms and modern mathematical filter methods have to be composed.

Fig. 16

GNSS theft protection system quickly alarms the construction site

Inertial measurement units (IMUs) in connection with great effort in terms of data filtering will play a great role in the future geodetic technology, because they are able to fix the coordinates of a moving object down to [mm] accuracy together with GNSS as a frame. So the coordinates of any moving object can be created coincidently. One scientific challenge of the hour is the high-precision time adjustment of the different moving sensors.

The New Age of Geo-Information

Geodesy means basically the technique, which connects freely selected points with an imaginary line. This technique got social and economic importance with the property cadastre. The border points were surveyed, and the imaginary line between them was the property boundary. It is the borderline between the spheres of activity between neighbors. These borderlines are the most important legal and economic reference frame (Schuster 1997). Most of the authoritative actions and private measures relate to that system. Coordinate systems – as described above – are from that view auxiliary systems, which ease to comprehend the economic life.

Two hundred years ago, the installation of such a reference system “property borders” needed a huge economic effort of the authority. Today, the sum of new technologies enables the geodetic community to give a coordinate to all points, on which the society wants to imprint its will. Since that procedure happens quickly, the movement of objects or even that of men can be documented in such coordinate systems.

Vice versa every coordinate created bears a certain information, the geo-information (3. Geo-Fortschrittsbericht der Bundesregierung 2012).

Seen from an economic viewpoint, the elements of the unnumbered nature and that of human privacy become finite-measurable. This means that water, air, wood, etc. a hundred years ago were unnumbered “free goods”; every human being was allowed to use or pollute them. Since the pollution is measurable, every tree is identifiable and such countable items run short in the mind of the people and economically as well. They even run short in a double sense of the word, physically and economically.

The information – attached to the coordinate – has a value, even when it is outdated. This value has not an eigenvalue in the economic sense; it has only a value in relation to the primary object: the “plot” or the “natural person” or “legal entity.”

These newly created huge amount of data need an evaluation to be understandable. Therefore meta-levels are needed, which means the graphic design in gliding scales and gliding adapted degree of abstraction.

Meta-data as well mean numerical description, the naming of maps and the description of the accuracy of the coordinates or related structures.

The public authorities gain a lot of advantages for their work on future topics like climate, energy, mobility, sustainability, and demographics. The European authorities started early with INSPIRE and Copernicus (former GMES) (Allessandro and Claude 1999). On national and regional level, the European structure got substructures (i.e., GDI-DE) partitioned to responsibilities.

The INSPIRE directive gives the legal frame for that Europe-wide geo-data infrastructure.

Worldwide suppliers of geo-information like Google or Microsoft today seem to be unavoidable, and they disperse in the economy with new business models (Barwinski and Schuster 1988; Schuster 1997).

Discussing the naming of this new field of work, international groups decided to change the term to “geomatic” to show that the geodesy has expanded its field.

Geodesy as an Economic Sector

It is comparatively simple to value the costs of an economic sector on the European continent, because the professionals remain for a very high percentage of their professional life in their profession once chosen.

The “Market Report” presented by the Comité de Liaison des Géomètres (CLGE) and Geometer Europas (GE) (Schuster et al. 2003) comes to the conclusion that the volume of costs, deduced from the salary payments to geodetic professionals in the year 2000, is about 24 billion €. This sum comprises those who are busy with the maintenance of the public property system and public maps as public servants, as well as those who are active in the private business life in form of surveying, evaluation, and software (Schuster 2003).

Given that the predominant part of demand in geodesy is due to the building applications, Fig. 17 shows the dramatic changes in demand since the 1950s and the steadily growing number of supply (number of private offices) in a state like North Rhine-Westphalia with about 18 Mio inhabitants.

Fig. 17

Dramatic changes of supply and demand

The private service structure of the supply answered with the reduction of personnel and an furthermore improved its offering with better quality of comprehensive services on the basis of the extending public regulations; the public structure passed several waves of reorganization but benefitted from the extending relevant legislation.

So, the demand for geodetic supply is relevant to the legal situation of land as a whole. The differences between countries can be huge.

In a developed country like the Netherlands, the geodetic community speaks about “crowdsourcing,” which means that the owners themselves are able to identify the property boundaries between their parcels on the basis of a well-explained cadastral information of the public authority.

The Internet now has brought up a new situation, where some hundred experts, i.e., from Google and Bing, can theoretically reach the whole mankind with their products. The funds for this investment and its maintenance come mostly from sources outside of the professional sphere (i.e., marketing). The underlying business model couples different sectors, which is not unusual in the economy (Schuster 2004).

Whereas the old business model of the geodesy was relatively closed and strongly regulated and could be broken down into

• Public mapping

• Maintenance of cadastre

• Cadastral surveys

• Sequent control of building geometry,

the business field expanded its supply strongly by the vast new field of sensors, the practically unlimited possibility for the geo-referencing of any object, and the use of the Internet. The enlargement of the supply is financed in the middle-class economy by the old business, big public investments, and the hope, which was induced by the technological progress. The demand is lagging behind, which means generally low prices for the services.

The situation in various European countries is different, and it is scarcely straightforward because of the degree of regulation, not to mention the clearness in detail. Beside such difficulties one can say that the old geodetic business model was pillared by:

• Ground tax

• Transaction traffic

• Settlements

• Military needs

• Sequent control of building geometry

Nowadays is upcoming a growing income for the use of most different geo-information. One quickly spreading example is the area cadastre. With this GIS the communities are able to split the fees for percolation water and sewage. New services are created. With the cadastre of trees, of greens, and of public eases, they help to manage the real estates and have an organizational added value.

Many people look forward to a growing activity in geodesy. But the answer to the question is not yet clear, until new “biting” business models and broader economic trends will show up. Undoubtedly, they will deform the old economic basis.