Survey Methods - section one: sketching
A field sketch usually takes the form of a simple plan or site plan that represents a vertical bird’s eye view of your site. Undertaking a field sketch provides an extremely useful way to gain an overview of your chosen building(s) or site. It is an ideal way to assess the number of buildings and other structures present, as well as aspects of their construction, phasing and spatial relationship. A well-drawn field sketch can provide a very useful record of a site or building in its own right, or may become the first stage in the process of producing an accurate scale drawing. At its simplest, a field sketch need only show building outlines and orientations – often referred to as the footprint.
If there are reliable contemporary maps available that provide you with information that will assist, you could use these as a starting point or perhaps an aerial view from a source such as Google or Bing maps.
Be aware, however, that the information that any map contains might be outdated or incorrect and you should double check measurements on site; there is a strong case for – at least initially – creating your sketch independently to avoid any prejudices or misleading influences.
• clipboard/drawing board (with paper, waterproof paper, or polyester film fastened with masking tape)
• pencil (test whether HB, 2H, 4H or 6H is best for you depending on the medium
• eraser and pencil sharpener
• ruler (scaled)
• set square/T-square
• magnetic compass
• extracts from OS maps showing the site and any other available mapped data.
Annotated/dimensioned field sketch (running sizes)
You can increase the value of your sketch by adding notes and measurements. This will particularly help you if you intend to carry out further work such as writing a site description from a scale drawing. The aim is to annotate your sketch plan with accurate measurements to show all the necessary dimensions for someone who has not seen the building to be able understand it and construct a scale drawing from the information it contains. Ideally the sketches should be neat, in proportion and large enough to allow the required dimensions to be clear and legible.
Cumulative measurements, known as ‘running sizes’, taken from a single point of origin are preferable to a series of separate measurements. You can repeat the process for different planes of a structureor, where it is feasible to do so, run in a clockwise direction round a room, or building. The origin point for running sizes should be clearly marked, although you may have several on a complex site. Include diagonal measurements to check such things as room proportions and wall thickness measurements where possible.
If you are recording running sizes of an interior remember to measure the diagonals to ensure that you have the correct proportions; few buildings have true right angles. If it is possible to do so, youshould also record wall thicknesses, which are likely to vary depending on their location within a building. This information can often help inform the chronology of a building that has been modified over time. Note also any significant changes in floor or ground level and provide height information where possible. This method is appropriate for plans, elevations or details of buildings/structures with relatively simple geometry.
Scaling a dimensioned sketch
If you produce a dimensioned sketch, the information can be readily used to create a scaled plan or elevation, even off-site. A scaled drawing provides an accurate plan of a structure or site; it is a drawing where measurements taken directly from the plan can be easily converted into the actual dimensions on the ground.
Creating a scaled drawing can help significantly in the interpretation process. During the process you will be recording what is there today – what the building/structure comprises and how it might have changed over time, in both appearance and use.