Isometric drawing is a method of technical drawing for communicating designs for man-made objects. They are a utilitarian form of drawing and not normally used for fine art purposes. The fact that isometric drawings are not used for fine art makes them all the more appealing for me… they exist purely to explain a concept or procedure, to communicate a message. They are not confused and dance around the topic, they just tell it how it is. They are not suffering some neurosis about whether they are considered sufficiently arty or not.
Isometric drawings communicate the construct of an object or building, and can be exploded (with all components separated out to show their construct better) or not exploded – that is all surfaces joined as one object. Isometric drawing is not designed to replicate the manner in which humans see, the way that drawing with perspective is designed to. Perspective accounts for the way humans perceive objects in the distance as getting smaller, and is the main method used for communicating depth in artistic painting and drawing.
Isometric drawing does not consider perspective at all, therefore objects in the distance do not shrink, they all remain the same size. The purpose of this is because it is easier to construct designs with computer technology when perspective is not involved (calculating perspective in game design for instance, such as the Sims, below, is very difficult) but also to make it easier to show all planes of an object or scene equally. All three dimensions are given equal weighting, making it perfect for communicating designs or 3-dimensional concepts in design and architecture.
For this reason, isometric drawing goes hand in hand with infographics, which are graphic elements made to communicate concepts. All examples below show aspects of infographics as well. In particular the isometric drawings show graphical elements, in the Sims it is bar graphs and icons. In the diagrams, measurements and other text is displayed in columns and tables and alongside edges of shapes. In the architectural drawings there is also tabular data accompanying the drawings.
Isometric drawing can be done on paper, or more easily and accurately, on the computer with appropriate graphic design software. Many use special ruled isometric drawing paper, or dot isometic drawing paper. The angle of lines is very important in isometric drawing. While it is possible to use low angle, medium angle, or high angle isometrics the most common and traditional angle is 30 degrees. That is, all angles fanning out from a point (eg corner of object) must be 30 degrees. Isometric drawing papers (ruled and dot) are measured to have angles at 30 degrees.
In Photoshop an easy method might be to have a layer designated as the ‘isometric paper’ with the 30 degrees ruled on it, which can be turned off at completion and preview. In isometric drawing there is no frontal plane, instead the front is an edge or corner. Mathematically, this makes sense, since we have three dimensions with 30degrees, each dimension is given a 120 degree ‘slice’ each (360deg total).. Essentially the three dimensions are just a circle which has been cut in three with a Y shape. The light blue corner of the building/terrace in the Sims clearly shows this.
Other less used methods of isometric drawing include low angle, medium angle and high angle. In these the angle used as a guide is altered for different purposes – low angle is best for intimacy and closeness and hides the upper plane most, whereas high angle is best for distance and showing scenes from above, as it shows more of the upper plane. In all cases the vertical lines must remain vertical, it is only the other edges that are angled.
Isometric drawing is similar to another tech drawing technique called ‘oblique drawing’. Oblique drawing also uses set angles and does not use perspective, but characteristically it always shows the frontal plane.
‘Isometric Art’ tutorial https://www.youtube.com/watch?v=cdxJQFXsxXQ
MIT Isometric Drawing notes http://web.mit.edu/16.810/www/Isometric%20Drawing.pdf