Perspective in drawing or in a painting is one of those things that while it seems simple enough in theory to actually implement it in a drawing is another matter entirely. While you can get away with not using perspective in many drawings such as one where you can’t see off into the distance as soon a you start adding items to the background or just items behind others things will start to look odd. this is because humans are used to seeing things in perspective as we are used to seeding things in 3D as soon as you take that away people notice that something is wrong. The issue with working on a 2D surface is that there is no depth so you have to create the illusion that it is there. to accomplish this you can use perspective (light, shadow and the placement of objects in a scene also plays a part but that is another subject to be looked at later).
There a several thing you need to know before you start to draw objects in perspective these are the vanishing point and the horizon line, the names do a good job of indicating their purpose.
This is a horizontal line that marks the horizon in the image it is generally (across the center of the page) at the same height as the eye line of the viewer if they were standing in the foreground of the drawing, but it can be moved up or down. If the horizon line is moved down it gives the impression that you are looking up and if it is moved up it gives the impression of looking down.
This is where all the lines converge in most cases on the horizon line. There can be one or multiple vanishing points in an image and depending on the complexity of the image they are usually but may not always be on the horizon line but they all do the same thing as shown in a later image. The number of vanishing points in an image is also not fixed although it is generally between one and three there can be more and this depends on the effect you are looking for and will be explained in a later post.
The above image is a good example of perspective at work as you can see everything is converging on a central point (the vanishing point marked with a blue dot in the bottom image) which is located on the horizon (marked in pink on the bottom image).
While this is a simple case using only one vanishing point it should give you an idea of how perspective works .
In later posts I will show you how to draw simple objects such as a cube in perspective and from there you can continue onto more and more complex objects