Reinhold Weinmann, Iris Flechtner, Nicolai Freiwald and Bernhard Vogel
European Media Laboratory, Heidelberg

Architecture Base. A Database for 3D-Models of Buildings and Architectural Elements

Keywords: 3D urban modelling, Geographical Information System (GIS), historic Heidelberg

At the European Media Laboratory in Heidelberg we are using Geographical Information System (GIS) technology to develop an information system for the city of Heidelberg. A geo-coded database linking its content to objects and people, allows the user to access multimedia information such as text, maps, photographs, historic views, short videos and 3D-models. All data are not only geo-coded three-dimensionally, but also time-coded, supplying each object, event or person with time-specific data. The user can, therefore, query the system about historic events and periods related to persons or objects. The user can also examine changes to particular buildings as well as the whole townscape through time, by means of a 3D-model. Various sources are available for the reconstruction of the townscape and the buildings of distinct periods. In most cases these sources, such as old engravings, are not sufficient to reconstruct complete objects. Therefore, a database containing elements of buildings from different periods is being developed. The elements of this database are related to their functions - windows, doors, roof parts - as well as to historical and geographical roles. These architectural 'building blocks' can in turn be used to complete models of buildings where no detailed information is available. Such reconstructed elements are modelled on existing historic buildings which have survived in Heidelberg and in nearby towns. The fusion of information gathered from historic views, old ground plans and the database, which has been named Architecture Base, will allow the 3D-modelling of Heidelberg in different centuries and thus provides the user with a 4D-information-system for virtual travels in space and time. This paper discusses the demands on the functions of Architecture Base from the point of view of architectural history.

1. The making of a 3D-model of a building

The first part of this paper is concerned with the making of 3D-models and introduces the issues relating to the construction of the 3D-models of buildings and other architectural elements. It will show which kind of knowledge base within our Architecture Base is suitable for storing and managing the data enabling documentation, discussion and support throughout the making of a 3D-model.

1.1. Researching the sources

The first step on the way to a 3D-model was to research the historical sources that could be used as the basis for the reconstruction. ¹ This research identified usable sources for buildings in Heidelberg. Heidelberg is one of the few cities in Germany whose rich written and iconographic sources relating to the city's townscape span more than five hundred years. The research has determined sources available for historic buildings in Heidelberg and established periods and planning stages to which those sources correspond.

Architectural drawings, ground and site plans, as well as engravings of historic buildings in Heidelberg can be found in archives, libraries, museums and private collections. ² With some buildings it is possible to follow their transformations over the centuries. It is, however, almost impossible to identify period features of those buildings whose original architectural details have been obscured by later additions. Furthermore, most of the sources only show the front of the building (Fig. 1A and B). For some buildings, which were once the landmarks of Heidelberg's townscape, detailed information is missing. Detailed architectural designs and historic photographs that can be used directly as a basis for the 3D-recontruction are available for only a few buildings.

Fig. 1A. A 1925 photograph of the Kollegienhaus in Heidelberg. Demolished 1929. Photo: Foto Lossen, Heidelberg.

Fig. 1B. The 1827 design for the Kollegienhaus in Heidelberg. Detailed architectural drawings and old photographs that can be used directly as a basis for the 3D-recontruction are only available for a few buildings. Architectural details of the Kollegienhaus can be identified in this drawing of 1827 and photograph of 1925 (Fig. 1A) but there is no information about the rear view of the building. Reproduced after F. Arnold: Projekte der Höhern Bürgerlichen Baukunst (Karlsruhe, 1831).

To fill this information gap, it was necessary to study architectural elements of extant buildings in Heidelberg and towns nearby. These elements indicate the specific stylistic forms in different periods. Finally, the 3D-models can be developed by fusing architectural elements of the real buildings with those identified in historical sources. The example that follows explains the steps taken once the investigation of sources has been completed. Furthermore, this example demonstrates that particular designs, which were not executed, can be shown as a model - but without the characteristics of real architecture.

Nazi architecture in Heidelberg. Hans Freese's plans and designs for a new town centre.

In the Third Reich period a new town center was planned for Heildelberg. The architect Hans Freese drew plans for a new main street to be laid out to the west of the old town. ³ He designed a 1.5-kilometer street in the district, where the railway station with its track system and adjoining buildings have been located since 1840. A new station, festival house, administration buildings, the National Socialist Party headquarters and a bank were also to be built. A public garden with fountains was planned as a feature for the new, main street block. The planning of this district has been a challenge to architects since 1850. ⁴

The discussion of Hans Freese's designs for Heildelberg centered on the principles of Nazi town planning as a reflection of the National Socialist ideology. One question in particular gained in significance: What influence do ideologies have on the urban planning? The intention behind the production of the 3D-model was to illustrate the principles of the Nazi way of designing buildings.

With the existing plans and the 3D-model of the street block it is now possible to explore the character of the buildings as well as their impact on the viewer. This also allows us to determine the functions of fascist architectures in the townscape.

1.2. Adding the third dimension to the architectural drawings

Elevation drawings of the façades at a scale of 1:500, as well as perspective drawings and site plans at a scale of 1:10000 - found in the Heidelberg archives - were used in the making of the 3D computer model. The elevation drawings of the façades and the site plans date from the third planning phase completed by Freese in the winter of 1940-1941. ⁵ The perspective drawings date from the last planning phase in October 1942. ⁶ Measurements of all parts of the buildings, including the façades, can be calculated using the elevation drawings of the façade but the drawings do not give any information about the depth of the door and window frames. To determine the depth of mouldings, jambs and door frames it was necessary to use photographs and drawings of existing, comparable objects. Using such models it was possible to calculate the proportions, including the ratio of the dividing elements to the height of the façade.

Comparison of the photographs and elevation drawings of façades of Nazi buildings that have survived in other towns was particularly useful. It is characteristic of Nazi architecture not only to show an almost identical style and design of façades, but also to use standardized building materials. ⁷ It was, therefore, necessary to find photographs and plans of buildings, which related directly to Freese's designs. Freese is known to refer to a number of buildings that influenced his designs for Heidelberg. The photograph of the Neue Reichskanzlei in Berlin ⁸ served, for example, as a model for the mouldings of a building probably intended by Freese to house a bank. The ground storey was based on the Haus zum Elephant in Nuremberg. ⁹ The same model buildings can also be used to render the window frames, transoms and doors. Freese's drawings of façades show these elements only as black planes (Fig.2).

Fig. 2. Hans Freese's design for a bank. Detail from Heidelberg. Umgestaltung der Westvorstadt, dated 10 February 1941. Stadtarchiv Heidelberg.

The materials and colour scheme used in the façade have also been established through a comparative study of the iconographic sources. In addition there are contemporary descriptions referring to the preferred materials and paints at that time. The architects often used shell-limestone for the construction of the rusticated ground floor; travertine was often employed for the windows and cornices. ¹⁰ The use of white plaster was influenced by the façade of the Neue Reichskanzler in Berlin. Two sources provide information about the scale of the individual buildings: one is the perspective drawing 'Neugestaltung Heidelberg. Vorschlag für die Bebauung am Bismarckplatz und nördlichen Brückenkopf. Maßstab 1:2000' (dated 25 November 1940). Buildings with four wings, designed for the area between Adenauerplatz at the bottom of the new main street and the central station, are characteristic feature of Freese's designs. The second source is a more detailed perspective drawing of the Festspielhaus (dated March 1941). It shows almost the entire street block and gives the sense of the structure of this theatre building.

1.3. The modelling

Freese's drawings of façades offered a rare opportunity to create a 3D-model of a whole street using the sources identified above. The experience thus gained will be particularly useful to the future projects, in which not just a street block, but a square, a quarter or even a whole town may be reconstructed virtually.

As far as the bank is concerned, first the shape of the building with the ground floor, upper storey, roof and mouldings was outlined using the measurements of the drawing. This outline was extruded along a path, which was set parallel to the ground plan of the building (Fig. 3). A core structure was thus formed to be used as the basis for modelling the building. The single architectural elements were then modelled: windows, doors and friezes. The position of the respective architectural elements within the core structure has been determined on the basis of the available drawings.

Fig. 3. The figure shows the blue outline and the core structure of the bank. The core was created by the extrusion of the outline along the walls of the building.

Windows, doors and friezes were then attached to the core. Finally the materials of the different elements of the buildings were rendered. The textures imitate shell-limestone, white plaster, travertine and tiles (Fig. 4).

Fig. 4. The façade of the bank. Massive cornices separate the second and third storeys from the roof and ground floor, emphasizing the horizontal structure of the building.

1.4. The interpretation

The comparison of the façade drawings makes it clear that every building of the new central street was designed according to the same architectural principles. All three- and four-storey buildings are the same height. Only the court building is higher. The heights of the storeys vary. All buildings have rustication at the ground level. The first floor is usually designed as a piano nobile and the third floor as a mezzanine. The height and design of the tiled roofs are standardized. The massive cornices impose upon the buildings a distinctive appearance of a horizontal structure. The cornices divide the ground floor and roof from the intermediate storeys. In that way every building is given a rigidly articulated structure (Fig. 5).

Fig. 5: The computer models of the façades of the post and tax offices and the court of justice. The comparison of the façade drawings makes it clear that every building of the new central street was designed according to the same architectural principles.

The presumed function of the building had no effect on the design of its façade and this fact emphasizes the predominant standardization even further. No building, whether the post office, tax office or court of justice, displays its function. The façades are in principle interchangeable. Although the appearance of the buildings is not similar, the effect of monotonous standardization prevails. The impact of the uniform town architecture upon the visitors to Heidelberg would have been that of strictness, rigidity, force and discipline. The rustication of the façades through the use of square stones or slab cladding, added to this impression. Monumentality, force, discipline and roughness are the terms which sum up the intention to represent military virtues. ¹¹

The façades of these buildings served as a setting for mass rallies and suited well the military spirit of the Nazi propaganda. Through the new architectural projects for the city of Heidelberg, the Nazis intended to strengthen the belief in cultural values and the willingness to defend them as carriers of their ideology. Other German towns were intended to follow the example set by Heidelberg. ¹²

In conclusion, the steps in the making of a 3D-Model can be identified as investigation and evaluation of the sources, modelling and interpretation. These steps lead to the evaluation of the functions of the Architecture Base.

2. Architecture Base

This paper is not concerned with the storage and management of the 3-D computer models, but with the process of their creation. A detailed description and discussion of the issues related to making a specific model is particularly important for the reconstruction of the former appearance of an entire city throughout different centuries. Such a description and discussion of the individual model will play a central role in the Architectural Base. It is here that the results of the historical and art-historical research, which contributed to the making of the model, are all documented.

If not accompanied by an art-historical or historical commentary, a 3D-model may serve as nothing more than entertainment. The model alone cannot provide enough information. The following section outlines the procedures that should be implemented in the Architecture Base to ensure that all the information it contains about the models is available, as well as ensuring that proper installation, storage and management facilities are in place.

2.1. Recording the sources

The Architecture Base should allow the examination of a 3D computer model on the basis of the information it provides. This requires a thorough documentation of the sources used in the making of the 3D-model. Site and ground plans, drawings, descriptions and all other sources should be stored in the database. The origin of every source, its nature and condition should all be described. The significance of the source in providing the information for the making of the 3D-model should be summarized in a comment.

2.2. Recording the making of the model

The procedures employed in the making of the 3D-model should be described in detail and made understandable to all users of the Architecture Base. The problems that have arisen during the modelling should be discussed and their solutions, if available, should be documented as well.

2.3. Discussion of the alternative interpretations

Freese's drawings do not indicate the exact design of the window-frames and doors; no indication of the materials or colour schemes for the façades has been located. In order to reconstruct his windows and doors and the colour for the façades, as well as other materials envisaged by Freese, it was necessary to rely on photographs and descriptions of real buildings. No documentary evidence is available for these elements. Any element, which has been reconstructed without supporting historical evidence, must be marked on the 3D-model. Possible alternative interpretations should also be recorded. The reasons for the eventual choice and contradictory opinions by scholars should all be included and discussed.

2.4. Identification of the chosen reality

The number of sources available for the Nazi development plan for Heidelberg is unusually high. Other periods lack such rich evidence. No written or graphic sources exist for the reconstruction of medieval Heidelberg. The extant buildings are in some cases the only models for a historic reconstruction. When a historic reconstruction of a building or an architectural element relies entirely on today's appearances, it is necessary to mark clearly the relevant part(s). In such cases the exact description of the real object is also very important.

2.5. The role and interpretation of the model

The computer model and its details help us to assess the impact of a building at the time of its original construction and to understand the different meanings of its architecture. The description of the building's impact and contemporary reception relies on the sources, as well as on the functions and characteristics of architecture in general and the historical and art-historical knowledge of the period. The evaluation of the model reflects the procedures adopted during the research undertaken prior to its making.

2.6. Procedures adopted during the modelling

As a result of the similarity of the architectural elements used by Freese in his designs, it was possible to re-use the same windows, pilasters and friezes created for one building in all other buildings in the street. Only a few Nazi designs were realized in Heidelberg. The 3D-models will, therefore, not be used for the reconstruction of further buildings.

Fig. 6. A photograph, showing the construction and the 3D-model of a window in the Friedrichsbau in Heidelberg, built from 1861 to 1864. The 3D-model of this window can be used for the reconstruction of houses from the 1860s. (Construction of the window, Universitätsbauamt)

The search for motifs characteristic of Heidelberg's architecture in other periods is far more interesting and makes historic reconstructions possible. Parts of buildings dating back to the eleventh century have been preserved in Heidelberg and its environs. Romanesque windows topped with round arches, Gothic doorways and Baroque mansard roofs can be reconstructed by copying the existing buildings and storing their records in our Architecture Base. This collection of building elements can be used to create a set of models for different buildings. Such an information system provides the user with tools for studying distinctive characteristics of a style and the development of a building.

The multiple use of 3D-elements in more than one model greatly simplifies the modelling. The multiple use of architectural parts in the reconstruction of Heidelberg's townscape is possible in every period. In some cases the same element can be used in buildings dating from different periods. This is also reflected in today's townscape, especially in buildings from the 18th to mid-19th centuries (Fig. 6). In order to make multiple use of the same element, specific functions must be assigned to building parts in the Architecture Base. It should be possible to select a part or the whole element and use it in various scales. For example, a window-frame can be used for many other 3D-models of windows. The information about the coordinates indicating the position of different elements within the model should also be stored.

Conclusions

The user of a city information system will be able to experience, by the means of 3D- models, the transformations undergone over the time by a single building, as well as the entire city. The making of these 3D-models requires different types of investigation. The functions of the Architecture Base include storing and managing 3D-models and architectural elements together with the information about their creation. These functions will enhance the communication between historical disciplines and computer modelling. In addition, the functions of this database will support the creation of 3D-models. As historical evidence is generally insufficient to create complete virtual buildings, 3D-models made after the existing historic buildings will be created and stored in the database. Where no detailed historical information is available, the database should make suggestions about how to create models and support the model synthesis. Problems will arise as a result of the difficulty of storing the intermediate versions of models. The same architectural forms were used in different periods and the use of current forms is also spatially and functionally dependent.

The creation of the content of the Architecture Base is a challenge to all historical disciplines: architectural and urban history, preservation of cultural heritage and the representation of history by one medium, which is able to collate and manage various kinds of information.

Select Bibliography:

Bültemann, M. (1986), Architektur für das Dritte Reich. Berlin: Die Akademie für Deutsche Jugenführung in Braunschweig.
Durth, W. (1991), "Architektur und Stadtplanung im Dritten Reich", pp. 139-171. Nationalsozialismus und Modernisierung. Prinz, M. & Zitelmann, R. (eds.), Bonn.

Durth, W. & Nerdinger, W. (1996), Architektur und Städtebau der 30er/40er Jahre. Bonn: Deutsches Nationalkomitee für Denkmalschutz.

Frampton, K. (1978), "A synoptic view of the architecture of the Third Reich", pp. 54-87. Oppositions, 12.

Gottschall, W. (1987), Politische Architektur. Begriffliche Bausteine zur soziologischen Analyse der Architektur des Staates. Bern, Frankfurt am Main, New York & Paris.

Hinz, M. (1984), Massenkult und Todessymbolik in der nationalsozialistischen Architektur. Köln.

IEEE Multimedia Vol.7, No.2, April-June 2000 (http://www.computer.org/multimedia/mu2000/u2toc.htm) [requires subscription]

Käs, R. (1992), "Gebaute Gewalt 1933-1943", pp. 49-88. Kulissen der Gewalt. Das Reichsparteitagsgelände in Nürnberg. München: Centrum Industriekultur Nürnberg.

Koch, C. (1995), "Bauen in Nürnberg 1933-1945" , pp. 14-113. Bauen in Nürnberg 1933-1945. Architektur und Bauformen im Nationalsozialismus. Diefenbacher, Michael (Ed.), Nürnberg.

Laudel, H. (1984), "Das Luftgaukommando Dresden - Umgang mit einem Militärbau aus der NS-Zeit.", pp. 118-125. Architektur und Städtebau der 30er/40er Jahre. Bonn: Deutsches Nationalkomitee für Denkmalschutz (Ed.).

Lurz, M. (1978), "Erweiterung und Neugestaltung der Heidelberger Stadtmitte. Pläne vor, während und nach dem Dritten Reich zur Verlegung des Hauptbahnhofs und zur Neugestaltung der frei werdenden Gleisanlagen im Bereich der heutigen Kurfürstenanlage", Heidelberg: Neue Hefte zur Stadtentwicklung und Stadtgeschichte. Heft 1.

Münk, D. (1993), Die Organisation des Raumes im Nationalsozialismus. Bonn.

Petsch, J. (1976), Baukunst und Stadtplanung im Dritten Reich. München. Schlechter, A. (1999), Kostbarkeiten gesammelter Geschichte. Heidelberg und die Pfalz in Zeugnissen der Universitätsbibliothek. Heidelberg.

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September 2000

Notes

1. See Addison, A. C. (2000), "Emerging Trends in Virtual Heritage", p. 22. IEEE Multimedia, 7.2.

2. For an overview of the sources see the following books: Schlechter, A. (1999), Kostbarkeiten gesammelter Geschichte. Heidelberg und die Pfalz in Zeugnissen der Universitätsbibliothek. Heidelberg; Winterberg, T. (Ed.) (1996), Heidelberg im Wandel der Zeit. Graphische Darstellungen der historischen Stadt. Heidelberg.

3. For the biography of Hans Freese see: Lurz, Meinhold (1978): Erweiterung und Neugestaltung der Heidelberger Stadtmitte. Heidelberg, p.18.

4. See site plan 'Heidelberg. Umgestaltung der Westvorstadt. 25.11.1940. Hans Freese'. Stadtarchiv Heidelberg.

5. The drawings concerned are: 'Heidelberg. Umgestaltung der Westvorstadt. 10.2.41. Hans Freese' and 'Vorschlag für den Bahnhof Heidelberg Ost-Ansicht. 21.1.41. Hans Freese.' Stadtarchiv Heidelberg.

6. See the perspective drawings 'Neugestaltung Heidelberg. Vorschlag für die Bebauung am Bismarckplatz und nördlichen Brückenkopf. Okt. 1942' and 'Festspielhaus für Heidelberg. März 1941. H. Freese.' Stadtarchiv Heidelberg.

7. See Bültemann, M. (1986), Architektur für das Dritte Reich. Die Akademie für Deutsche Jugenführung in Braunschweig. Berlin, pp. 63-88; Laudel, H.: "Das Luftgaukommando Dresden. Umgang mit einem Militärbau aus der NS-Zeit", Architektur und Städtebau der 30er/40er Jahre. Ergebnisse der Fachtagung in München. Bonn: Deutsches Nationalkomitee für Denkmalschutz, pp. 118-126; Käs, R. (1992), "Gebaute Gewalt 1933-1943", Kulissen der Gewalt. Das Reichsparteitagsgelände in Nürnberg. München: Centrum Industriekultur Nürnberg, pp. 49-88.

8. See Schönberger, A. (1981): Die neue Reichskanzlei von Albert Speer. Berlin.

9. See Koch, Ch. (1995), "Bauen in Nürnberg 1933-1945", pp. 14-113. Bauen in Nürnberg 1933-1945. Architektur und Bauformen im Nationalsozialismus. Diefenbacher, M. (Ed.), Nürnberg.

10. See Lurz, M. (1978), "Erweiterung und Neugestaltung der Heidelberger Stadtmitte. Pläne vor, während und nach dem Dritten Reich zur Verlegung des Hauptbahnhofs und zur Neugestaltung der frei werdenden Gleisanlagen im Bereich der heutigen Kurfürstenanlage", Heidelberg: Neue Hefte zur Stadtentwicklung und Stadtgeschichte. Heft 1, p. 65.

11. See Durth, W. & Nerdinger, W. (1996): Architektur und Städtebau der 30er/40er Jahre. Bonn: Deutsches Nationalkomitee für Denkmalschutz, pp. 26-27.

12. See Lurz, M. (1978), "Erweiterung und Neugestaltung der Heidelberger Stadtmitte. Pläne vor, während und nach dem Dritten Reich zur Verlegung des Hauptbahnhofs und zur Neugestaltung der frei werdenden Gleisanlagen im Bereich der heutigen Kurfürstenanlage", Heidelberg: Neue Hefte zur Stadtentwicklung und Stadtgeschichte. Heft 1, p. 51.