Reading the city through maps and drawings

Lecture 1, elective course arch5131D “Mapping.Drawing.Thinking” at School of Architecture, cuhk | 12 Jan, 2021

This session will be an introduction of how we read the city through maps and how it is used as a tool to understand social conditions. James Corner’s 2011 article The Agency of Mapping stated the potentiality of the maps and mapping as:

uncovering realities previously unseen or unimagined…
James Corner (2011) The Agency of Mapping

In this case, mapping become a creative instrument, a two-way action – while we project what we observe onto paper, it goes beyond the flat surface of a “map” and uncover what is underneath. It allows the unseen, and more importantly, the unimagined, to be revealed, following a sequence from reading to discovery to creation.

Mapping URBAN FORM

A few concepts should be introduced in order to have a common ground for discussion. From an architecture or urbanism perspective, what we read from a map is form, specifically urban form. The map gives information of the city’s physicality of , through the delineation of built vs open space, and as a research urban form. The Nolli Map of 18th century Rome is such a map, produced by the cartographer Giambattista Nolli in 1748, it is probably the most referred-to drawing to illustrate the idea of urban form. The mapping approach is based on the concept of figure-ground, which depict built form as solid (black) and open space as void (white). It has become the convention in representing urban form, and from which one can read clearly the urban fabric and pattern. A new perspective given by the Nolli map here is the inclusion of public interior as void (mostly churches or market building at the time), and now the figure-ground relationship has changed from [Built and Open] into [Private vs Public].

A similar method is applied here in a 1995 map of the old town in Barcelona, made by the Catalan architect Joan Busquest. It takes on the spirit of the Nolli map but added further layers to describe contemporary urban complexity. For example, in the color-coded legend shows listed monuments in yellow and contemporary construction in red. Comparing to the aerial map that also shows the solid urban fabric, a mapping exercise “uncover” additional information beyond the a view of simple figure-ground. This illustrate the potential of the act of mapping, how it can reveals information in multiple layers.

Mapping TYPES

The next premise is the understanding of different types of maps. The definition of a map is so broad that covers any type of drawings that has some indication of spatial relations. One way to categorise mapping types would be the spectrum from realistic representation of geographic information to the subjective intervention that conveys an idea through mapping. Along this spectrum, three main types of map: [Aerial Image], [Topographic Maps], and [Plan & Diagrams] are identified.

Aerial Map

The aerial image is the result of two technological advancement in the early 20th century, namely that of photography and aviation. Together it allows us for the first time to have a “bird’s eye” view of the land we inhabit, a transition from land-based to aerial-based cartography. In the beginning, it was used mainly for military purpose, as these aerial image of Hong Kong that was made to assess situation on the ground during WWII. The image shown details of bombing and sunken vessel, but reading it nowadays it has also revealed geographic formation of Hong Kong island and Kowloon peninsula before the city’s rapid urban development. The key elements that can be read from the aerial map are [Land, Water, and Built Structure].

After the war, the technology of aerial photograph is adopted to civilian use, which later became an important tool for land survey and urban planning. In the case of Hong Kong, the colonial government began to systematically make inventory of the territory’s land in the couple decades after the war. The aerial photograph is particularly useful to survey the rural area, where it was not practical to walk through the whole land and the aerial photo can give a full view of the landform and existing habitation.

Topographic Maps

Similar to the function of an aerial photograph, the topographic map attempts to give an objective (“true”) representation of the physical environment, but it is not bounded by the dimension and format of photography, therefore often used to give a comprehensive view of the whole territory. It predates aerial photography, as early cartography speculate on the land survey results to construct a comprehensive world view, it also were able to reveal more layers of information (such as underground infrastructure) than an aerial image can provide.

Looking into detail of this topographic map of Hong Kong in 1945, in conjunction with the aerial photo of the same time, the topographic map provides another view of the land with more information through graphical representation. Key elements on a topographic map includes [contour, roads, and settlement], which utilise graphic notations such as line-weight, markings and words to give quantitate information of the land and structure. What is highlighted here are the 3-dimensional topography with spot elevation, as well as the physical structure of roads and the extend of built settlement.

from “descriptive” maps to “projective” plans

The purpose of ancient maps in many cases were tied to representation of land possession or to plan for military strategies, which evolves into modern days the map and survey still carries the purpose of land development. Besides to document the existing condition, maps were widely used to make speculation of future land use, such as this old map of Hong Kong in 1941, produced by Sir David Owen to accompany a report of future development.

This illustrates a change in rhetoric from the map to the plan, which distinguish the nature of a descriptive “map” to a projective “plan”. Based on the topographic map of existing condition, plans were being made to describe future development and depict the speculative condition of how the land will be modified. This is a tool continued to be used today, if we compare the 1941 plan with this 2002 Outline Zoning Plan of the Central waterfront development, 60 years apart they still carries the similar method and ideas on land development.

Plans and Diagrams

Into the scale of architecture, the topographic map is also used frequently as a design tool. Taking the example of the plan for Pac de la Villette by Bernard Tschumi made in 1982, where the old area of Les Halles was cleared to be replaced by the new design proposal. This is precisely what a plan can do, to give an idea of the future state of the place before the actual building action. The plan, whether it is current or projected condition, still gives realistic detail of information regarding urban form and structure, while the diagram is further on to represents an abstraction of an idea…

The diagram here is used for an explorative purpose, to test different possibility of a conceptual framework for development, and to illustrate the evolution of the concept into built form. The diagram can also depict the different layers that constitute the environment. It is a two-way action – through mapping we analyse reality to understand the layers of physical condition, while the creative act of planning makes new layers and overlay them together in composing a new reality. This case of Tschumi’s plan also shows the use of three notation tool to construct a conceptual framework: Points to represent “follies” or small built structure; Lines to delineate paths and movement; and Surfaces to distinguish different zones or land material such as the lawn or paved area.

The three types: Aerial map / Topographic Map / Plan and Diagrams covers the spectrum of maps that is generally known, in successive degree of intervention (and therefore design). Our focus here would be the last two types – the topographic map and the plans and diagrams. Through learning the development of mapping in the 19th and 20th century, we will discuss how it is used as a creative instrument to document and to discover.

Mapping CRITERIA

In order to utilise mapping for projective or creative purpose, one more set of criteria we should keep in mind – in terms of scale and legend. These can be seen as the common language that we will use for many of our discussion in this course.

Scale

When we encounter a map, the first question to ask is often “what is the scale of this map?” What does that mean besides the actual distance represented on paper is the level of detail and information shown by the mapping or drawing. The (1) city map is usually in 1:50000 or 1:25000, which shows the overall land and urban form, and the extend of urban development and infrastructure. In a (2) district map, purpose of 1:10000 or 1:5000, the urban form in terms of building blocks can be distinguished, where we can read the pattern of the streets or open space network. The 1:1000 or 1:500 scale is often used in (3) an architecture masterplan or site plan, where the building develop is clearly delineated and elements such as the roofline or the courtyards, the interface of built and open space can be read. This is also the scale where there is the opportunity to integrate architectural ground floor plan with urban block plan, as in the case of the Nolli Map, which gives additional information of spatial flow and continuity from the exterior to interior space.

The second important use of scale is for comparison. Let’s look at an example of the area of Tsim Sha Tsui, Ma On Shan and Sai Kung. They are very different places in terms of urban fabric and therefore experience. By reading the maps of these different area at the same scale, we can understand the physical form (building massing) of urban form that makes these differences. The differences of the dense street blocks of TST, the individual houses in Sai Kung, and the large tower blocks in Ma On Shan are clearly delineated as they are compared in the same scale.

Legend

The other important supplement to any type of maps is the legend. It is the system of graphic annotation to represent different elements in space. Taking this Japanese map of Hachioji district in Tokyo, the legend has 4 basic type of annotations: (1) Lines, which include different types of roads and railways, as well as administrative boundaries; (2) Markers, where it denotes the location of important buildings such as the town hall, schools, hospitals, and historical monuments; (3) Hatches, that differentiate the extend of natural areas such as farmland, woodland or orchards; and (4) Graphic Notation of different components within an urban block, or landscape details of rivers and hills.

One thing to keep in mind is the legend demonstrate a deliberate choice of what to represent on a map. For example, this map of Hachioji district appears to be an objective and accurate depiction of the environment, yet it is not necessarily comprehensive or deterministic. The act of mapping in this sense is always political, by what is shown and what is not. (Ref: The Power of Maps)

Before we go into discussion about the politics of mapping, we should also look at another kind of legend – a representation of data. The Charles Booth Poverty Map of London produced in the late 19th century is an example of how social data is displayed spatially. On top of the black-and-white topographic map, the social class of inhabitants is annotated with a color spectrum from golden yellow (upper-class) to red (middle-class) to black-blue (lower-class). While in the full scale of the map shows geographic distribution of social class and neighborhood, the detail as it denote to the level of building block also describe the nuances in spatial character of different social status. For example, along the main boulevard are lined with middle-class townhouses, while the well-to-do houses usually facing the square. Analysis and readings can then be made with the data shown in this map, which we’ll come back to next week with the discussion of social cartography.

Besides the conscious choice of what or what not to map, there are two more notable points on how legend works on a map in practice. (1) the way of how data is classified reflects a certain kind of judgement, such as that in the Charles Booth map (and other social map) that usually relate household wealth as a proxy to define social class. (2) the use of color in relation to the psychology of viewer impression, as in this case golden yellow associated with wealth has a positive connotation, while the dark blue-black color to denote the poor is giving a negative impression. It might be decision based of effectiveness of graphic representation, yet it is nonetheless revealing a certain inclination in the making of the mapping.

The politics of mapping was a central topic debated during CIAM 4 (the 4^th international congress of architecture). The main work of this edition of the congress is the production of a series city-scale mapping of urban conditions for comparative analysis. While it was supposed to be an “objective” survey of the participating cities, it is also a manifestation of the functionality of a city as advocated by the congress. The four main functions: Work, Live, Leisure, and Circulation, are deliberately expressed through the use of legend, with different hatches to represent urban functions, as well as the annotation of worker number and their movement (circulation). If we compare with the Japanese map introduced earlier, it has a similar level of intricate details to depict a “reality”, although clearly in the CIAM maps there is a message to convey.

Mapping OPERATIONS

The last set of concept to build our common understanding of mapping is its Operation, which will also inform the process of our later mapping project. It is largely referenced to James Corner’s The Agency of Mapping, where he explained the three “steps” towards the act of mapping.

It begins with THE FIELD – how we setup the surface analogues to the actual ground. This action of framing is in itself a creative act, a conscious choice of what to include within the frame. The next step would be to EXTRACT – the main activity as a cartographer/researcher, to observe and select elements from the field to illustrate. Finally, what makes a mapping meaningful is the PLOTTING – to discover and “uncover” the hidden relationship between extracts. Based on the data collected and to make creative and projective links between them.

This introductory session has laid out the premise of our exploration through the act of mapping. In the next two sessions it will be a somewhat chronological narrative of cartographic evolution, and the last two sessions into the thematic discussion on contemporary topics.