An approach to visual interaction analysis of urban spaces. Central Barcelona as a case study

ABSTRACT

Beyond the binary, traditional, figure-ground reading of urban patterns, this research presents a graduated expression of the geometry of urban spaces from a perceptive point of view. This highlights the spatial relationships and introduces a new set of criteria to evaluate contemporary open spaces according to visual experience. The study produces an innovative reading of central Barcelona by mapping of Visual Clustering Coefficient, one of the parameters derived from the Visual Graph Analysis of isovists.

KEYWORDS:

• Barcelona
• public space
• visual graph analysis
• isovist

Acknowledgments

The authors would like to thank Júlia Sáez and Enric Pulido, architecture students at Barcelona School of Architecture (ETSAB) collaborating with the Laboratori d’Urbanisme de Barcelona (www.lub.upc.edu), for their support in the production of the Visual Graph Analysis of central Barcelona. This paper was inspired by the teaching on collective spaces and inner courtyards during the 4th course of Urban Design at the ETSAB, in 2017.

The authors would also like to thank the anonymous reviewers who, with their generous remarks, have substantially improved clarity in the presentation of the methodology, background and results of the research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1. An open source version of the software and documentation is available at: https://varoudis.github.io/depthmapX/Date accessed: 21/04/2019

2. A free version and full documentation of the software Isovist.org is accessible at: https://isovists.org/Date accessed: 21/04/2019

3. Some of the application of this methodology by Space Syntax Ltd can be found at: https://spacesyntax.com/urban-places/streets-parks-and-public-spaces/Date accessed: 21/04/2019

4. Despite the fact there is no English translation of this text, many years later the author published an adapted synthesis in Lotus International with the title “Space, time and the city/Spazio, tempo e città” (de Sola-morales 1986).

5. Other relevant lines of research that LUB opened at that time could be mentioned, such as urban topology and accessibility (Gómez Ordóñez 1971), an issue that received renewed attention in studies on the metro system (Parcerisa and Rubert de Ventos 2002).

6. To speed up computing for the 1,156,816 points that form the case-study grid, 10 + 10 subsamples of 1600 × 2400 metres were superimposed. Using this method, the deformation of the values generated at the edges was minimised. The aforementioned software Isovists.org can be used to compute the entire frame simultaneously, with greater resolution and speed. Further research will explore this software, which is now under continuous development.

7. Here the term “convex space” is used according to the definition used by Hillier and Janson in The Social Logic of Space, i.e., a “convex space is one in which no straight line drawn between any two points goes outside the space”(Hillier and Hanson 1984, 97). In intuitive terms, this geometrical concept is often related with concavity.

8. Inverse values of the clustering coefficient have been used to make an intuitive interpretation more evident.

9. In this case, a limitation in the generative process of the model should be highlighted, as the sea is represented as an opaque solid. This results in an image that cannot be discussed in the same perceptual terms as in the above cases: in reality, the other side can be seen. However, the VCC can also be interpreted as places for decision-making in pedestrian routes (Cfr. Turner et al. 2001, 111) and, therefore, the representation of the sea as an impassable solid is also accurate.

Additional information

Notes on contributors

Álvaro Clua

Álvaro Clua, PhD, is an architect and adjunct Lecturer in urban design at the Barcelona School of Architecture-UPC and a postdoctoral Researcher at the Barcelona Laboratory of Urbanism. He is the author of several essays on infrastructural landscapes, projects of urban articulation, urban history, and city mapping. Clua has been developing projects and studies of urbanism and architecture since 2013.

Carles Crosas

Carles Crosas, PhD, is an architect and Lecturer, teaching urbanism at the Barcelona School of Architecture-UPC since 2001. A former collaborator of and Assistant Teacher for Professor Manuel de Solà-Morales, he is a Researcher at the Barcelona Laboratory of Urbanism, where he is both the Coordinator of and a participant in various national and international projects dealing with ecology and metabolism, “hubscapes,” and the teaching of urban design. Since 2004, Crosas has been active as an architect and urban designer.

Josep Parcerisa

Josep Parcerisa, PhD, is an architect and Professor of urbanism at the Barcelona School of Architecture-UPC, Coordinator of the research program Urban Observatory of Cities, Founder of UR-Urbanismo Revista (LUB, 1985–1992), and Founder of D’UR Urbanism, Architecture and Cities Now, a new LUB project. He has authored several critical essays about Barcelona urbanism. Parcerisa develops urban projects for local administrations and consultantship works about public transportation and metropolitan urbanism.