Parallel projection is a projection of an object on an image plane using parallel lines and a projection direction.
So basically you choose an architectural volume that you want to draw in a parallel projection, then choose a projection direction and proceed to draw parallel lines to the projection direction towards a perpendicular projection plane.
The end result is a two dimensional drawing of a three dimensional object. Makes sense, right?
Now, you can have multiple parallel projections in architecture of the same object, but ideally you stick to the three projections which are the bare essentials.
A frontal projection, the object being seen from the front, hence you see it in a frontal view.
A top projection, the object being seen from the top, so you see how it looks in a planar view.
A side projection, the object being seen from the side, hence a side view.
These three fundamental examples of a parallel projection are enough so you describe an object in full detail, regardless of its level of complexity. If you understand how an architecture volume looks like from the front, top and side, then you can understand it enough to draw it.
Subtitle 1: Parallel projection terminology and notations
1. Chosen object
You start off by choosing an architectural object that you will next project on a projection plane. Ideally you go for something that already is in a type of axonometric drawing, so your final projections end up having scale and being relevant as a final drawing.
2. Direction of projection
You choose the direction of projection which is most relevant to the object at hand. I recommend you go for a 90 degree angle perpendicular direction on the object you want to draw.
3. Projection plane
You can choose any projection plane, but ideally it is perpendicular on the projection direction. This way the final image has less deformations and you get multiple lines in real dimension.
Subtitle 2: Properties of parallel projection in architecture
1. Lines parallel and perpendicular to the projection direction are in real dimensions
This is the most important part of parallel projection as it tackles the real life dimensions of what you are drawing. So again, if a line is parallel or perpendicular to the projection direction, then it has no deformities in the projection, hence it has real dimensions.
When a line is not parallel to the coordinate system you can use a planar change (we will talk more on that in the last part of the article)
2. You can draw multiple perpendicular projections together to get a triple projection
Triple projection is the best way to describe a volume in two dimensional technical drawing, period. The fact that you can modify something in the frontal view and have that change appear in planar view and side view makes it an invaluable design tool.
3. Starting from projections you can draw a different axonometric
Jump from axonometric to projections and then back to a different axonometric if you really want to grow in technical drawing.
This is the general idea of technical drawing – to be able to draw the same volumes in multiple technical drawings and be able to use this as a tool in your design arsenal.
Subtitle 3: Types of parallel projection
1. Two dimensional parallel projection
These two dimensional parallel projections explain an architecture volume by projecting it on three different planes: the frontal plane, the top plane and the side plane. These three, being correlated form a triple projection which is an excellent way of describing a volume using technical drawing.
2.Three dimensional parallel projection
The three dimensional parallel projection comes in the form of an axonometric – a three dimensional drawing which represents an architectural volume using three intersecting axees that form a coordinate system.
You can also see this as what happens if you take a frontal, top and side parallel projection and draw them together as a volume.
Subtitle 4: Parallel projection vs perspective projection
Now we will discuss parallel projections vs perspective projection – the pros and cons for each and when to draw them.
1. Parallel projection has scale and can be measured whilst perspective projection cannot be measured.
As previously stated, parallel projection is really good for understanding how the drawings will look like with real- life measures and scale – the job of an architect at the end of the day is to create plans and sections.
2. Parallel projection is abstract and 100% disconnected from real life, perspective projection can give a realistic look on how the design will would look like in real life.
Perspective is much more artistic and can show how the final drawing will look like, although you cannot measure it accurately without a constructed perspective. Even then, it cannot match a parallel projection in architecture as it has no scale, so no way of thinking of the real dimension of a plan or object in relation to other objects.
3. Parallel projection is mostly related to left brain, logical thinking whilst perspective projection is mostly right brain, artistic thinking.
Parallel projection is very straightforward at the end of the day – the only thing you need to worry about is having decent technical drawing graphics and then it all is a straightforward process.
Perspective projection is more artistic and much more non-linear in its process. All freehand drawings are different, so you need to grow your skills in sketching as well as constructed perspective in order to fully grasp parallel projection.
Subtitle 5: Master the parallel projection in architecture: Tips , tricks and exercises
1. Triple projections
Just like I have said before, you can match three parallel projections together and you get a triple projection. This way you can accurately describe a volume through two dimensional drawings.
Obviously, this handles only the line drawings part – if you want to really make your drawings stand out then you need to add graphics elements – this is a whole subject in itself.
You can start you parallel projection from an axonometric drawing and thus get a realistic two dimensional drawing from a three dimensional drawing. You can get all three basic parallel projections (frontal, top and side views) from a standard axonometric drawing.
And if you want to draw another axonometric in a different reference system then it is really easy to shift from the triple projection to the new axonometric system.
3. Planar changes
This is the most interesting part of the parallel projection as it implies that for you existing projection you can add an extra projection that is useful in your drawing.
The best example for this are planar changes in descriptive geometry exercises – we will talk about that in a future article.
4. Cast shadows
This is particular example of parallel projection as in this case the projection direction is the sun beam direction that is set as a standard for both two dimensional and three dimensional technical drawings.
1. Two dimensional shadows (for facade, planar view, side view)
The standard parallel projection direction for two dimensional shadows is 45 degrees. Here again it is ideal to match a planar view with a frontal view in order to get correct constructed shadows.
This can be quite a complicated process when you have multiple heights and curved volumes.
I tackle this in my lesson on advanced cast shadows – you can check out a preview here:
2. Three dimensional shadows (for axonometrics)
For three dimensional technical drawings (axonometrics) you need to project at 60 degrees and a horizontal direction. This basically means that the projection plane is the horizontal plane… and this makes sense, all cast shadows fall on the ground.
Although this sounds very complicated, it is very intuitive to draw. Here is a video preview of the lesson on axonometrics cast shadows from my course:
Cool, so we talked about A LOT in this article.
Go back and read it two more times so the information sinks in and I will talk to you soon!
Take care, draw nicely,