When we look at a building on site, we find ourselves in a specific ­relationship to it in terms of perspective. This means that the perspective is the sole realistic type of drawing you can draw without a further examination of the building. This is the great difference from projection drawings. A site plan, an elevation, or an axonometric cannot be pro-duced on site without walking around the building; you will not be able to draw an elevation correctly if you are not positioned at right angles to the building; you will not be able to draw a floor plan or a section if you have only looked at the building from outside.

Through the repeated act of looking closely, drawing on site encourages the development of a building archive in which patterns, geometries, structures, forms and typologies can be stored. The draughts person appropriates a building individually and produces a two-dimensional equivalent of the image that he or she has perceived, at an undefined scale.