Instructor's kit for O-mapping courses

Instructor's kit for O-mapping courses
Map design

Introduction

Before looking at the various stages in the production of an orienteering map, it is useful to look at the overall design of a map and the numerous disciplines that will influence the final map.

The Cartomium

E.S. Bos in trying to identify cartography as a science / technology in its own right developed the cartomium - a model showing all the areas of influence in map design. Those components at the centre of the cartomium can be considered cartographic while those around the periphery are allied to other disciplines that exert influence over cartography. Many of the peripheral components influence several of the map design components, for example the visual perception field will influence: map content, symbol design, generalization and map layout; hence there are no specific links shown within the cartomium.

The main components of map design are: map content, symbol design, generalization, layout and map production planning.

Determination of the map content is largely dependant on map scale, the intended use of the map, the available spatial data,
together with the marginal information.
Generalization is the process of a consistent representation of the content in accordance with the map scale and purpose.
Processes of simplification, exaggeration, displacement and selection will need to be applied.
All map attributes must be bought together in a well balanced way, keeping in mind aspects of perception and aesthetic norms
as well as costs and map application. This is the process of designing the layout of the map.
Symbol design is the translation of information to be mapped in graphical symbols. Several of the peripheral disciplines
influence the design of map symbols including: graphic arts and in particular the graphical variables component (the variables consisting of form, orientation, colour, density, value and size), visual perception on aspects of visibility and legibility, and
the spatial data when considering the map content.
Map production planning deals with the technological and economical aspects. It is related to the other core components but
most importantly these days to the technology discipline and the ever changing technologies used to assist in the map
production. The aspect of cost cannot be ignored for a map is only viable if the customer is prepared to pay for it.

The peripheral disciplines are not specific to map design but influence the final product.

Spatial data is collected by various means including field survey, GPS and photogrammetry and digital processing. Although not part of the actual map design without this data there would be no map.
Maps are always made for society, for a more or less well defined users group, and maps therefore have a specific application. It is this application that results in map conditions, these conditions are often global in character and are confined to conceptual and accuracy specifications, to map projection criteria, name spelling and certain costs.
Visual perception, in general terms, is related to the perceptual reaction of the map recipient to the information presented to him in graphical form.
Graphic arts are associated with the design and creation of an image and are limited to the various aspects of graphic design and visual communication.
Technology is continually refining the methods used to produce a map. The three main areas of technology that are associated with cartography are: graphic construction (drafting), graphic reproduction (printing) and digital processing. Digital processing
includes all computerized technology needed in data storage, data processing and data presentation. Digital processing techniques are additional to graphic construction and reproduction, or may partially or entirely replace them.

Some of the components defined in the cartomium are of no consequence to orienteering map design. These include: map projection - how spatial data on a curved surface is represented on a flat surface (the map) and spelling - the translation of place names between languages.

Other components such as symbol design and to a lesser extent map content are pre-defined through the IOFs publication -International Specification for Orienteering Maps.

There are some components which have no distinct boundaries such as the collecting of spatial data and generalization, the mapper will generalize the shape of the land while in the field.

Communication

The main purpose of the orienteering map is to convey to the user as much information as is necessary to navigate as fast and accurately as possible between the controls on a course. This requires the user to interpret the land form, the features and the runnabilty along the route and for his interpretation to be close to reality.

The map is therefore a communication tool with the mapper trying to communicate with the user through a graphic medium (the map). There are four discrete stages in the communication process:

Collecting and selecting the data for mapping
Manipulating and generalizing the data, designing and constructing the map.
Reading and viewing the map
Responding to or interpreting the data.

In orienteering, the mapper interprets the terrain, features and runnability as he sees them in the field and translates them into a map. The user reads this map to gain an impression of the terrain, features and runnability. As the user passes through the terrain he compares reality with his expectation. Depending on the competence of both the mapper and the user the closer the users expectation with reality will be. Where the competence of either the mapper or user is low the difference between the users expectation and reality will increase. One way of increasing good communications between the mapper and user is for the user to be fully conversant with the mappers symbology used on the map - hence the International Specification for Orienteering Maps.

A competent user will be able to make allowances for small errors in the map or in his interpretation as there will generally be sufficient good areas of agreement that the errors can be compensated. This is analogous to a communication signal where a signal is transmitted but noise en route causes a few letters be lost, provided enough letters are received the receiver can still read the message. The more letters lost on route the more difficult it is to interpret the message, there comes a point where it is impossible to understand the message!

Generalization

The Cartomium model defines symbol design as one of the important disciplines of map design. For orienteering maps a common symbology is used throughout and is defined in the IOF publication International Specification for Orienteering Maps.

The International Specification for Orienteering Maps has been written to ensure a legible map with a common map language that can be applied to all terrain types throughout the orienteering world. It includes the following:

Map Scales.
Contour Intervals.
Map content - type and minimum size of features to be mapped.
Symbol representation of features including: shape, dimensions, minimum dimensions where appropriate and colour.
Acceptable combination of area screens.
Minimimum graphical dimensions.

Once familiar with the contents of International Specification for Orienteering Maps it will become apparent that the fieldworker must be selective in the features that are mapped and the level of generalization required. On no account should features smaller than the minimum sizes be included on the map and on terrains with much detail the minimum size of features included may need to be increased, the mapper must ensure consistency across the entire map.

A large number of map symbols have minimum dimensions (either explicitly defined or implied from the minimum graphical dimensions). It should be remembered that the minimum symbol size equiates to a size in the terrain. If features are to be mapped that are smaller then the map symbol exaggerates the size of the feature!

Line and point symbols on the map often take up more space than the feature occupies in the terrain. For example: a road or path occupies more space on the map than it real width, small buildings are alway mapped and must be shown with the minimum size building symbol, other pont features such as pits and boulders occupy far more space on the map than they do on the map.

When a number of point symbols are in the same locality they must be displaced though retaining their relative positions for them to remain legible.
Care should be taken with their positions relative to other features nearby.

Where two symbols would occupy the same space on the map one of them must either be displaced or part of a linear symbol may be cut.

Obvious junctions or bends which if drawn to scale would not be noticable on the map should be exaggerated.

When two similar adjacent features are of different size but should be both shown with the minimum dimesions then the larger feature should be shown exaggerated. The orienteer would view two different size features in the terrain and would expect them to be shown on the map as two different sizes.

References

E.S. Bos, "Another Approach to the Identity of Cartography", ITC Journal, 1982-2, pp 104-8