These inferences can be made while at the scene or later, with a recreated scene or a drawing. The drawing also allows the jury to draw inferences at trial. Each can be elaborated upon or combined in a particular scene. Either distance or angular measurements are then made to objects in the scene from each of these two points. Dashed lines indicate measuring the lengths of base line and the two sides.
Solid lines indicate measuring the angles the two sides make with the base line.
The angle can be measured with either a large protractor or an optical device such as a transit or a compass. The protractor technique with a 360 degree protractor is useful for underwater scenes. The starting point must be fixed so it can be reproduced. Its distance from the corner of the building is indicated in the drawing. The simplest form of rectangular coordinate system.