Lesson 1: Lines, Ellipses and Boxes
Now that we've gotten used to using vanishing points in a direct, explicit fashion, let's look at removing those training wheels and trying to estimate our convergences a little. You'll find this pattern to my approach - I'll introduce certain tools and tricks, and steadily take them away as we strip these concepts back to their core.
As before, draw a frame on the page and a horizon across it. Place a single vanishing point on it, this time, as we'll be working in one point perspective. You can place this vanishing point somewhere more central - it doesn't need to be dead center, but don't put it too far off to either side.
You may use a ruler or straight edge for the frame and horizon line. Every line after this point should be drawn freehand, using the ghosting method.
Where the plotted perspective had us start off with the edge we were facing, this time since we're using one point perspective (and therefore oriented towards a face on each of our boxes), we're going to block out those faces.
In one point perspective, one of the horizontal vanishing points of our boxes is going to be at infinity, as will be one of the vertical vanishing points. As such, all of our vertical lines will run perpendicular to the horizon, and all of the horizontal lines will run parallel to it, leaving only one set of lines that converges (towards our single vanishing point).
Let's draw a series of rectangles within the frame - each rectangle will serve as the front face of a different box, and will define their height and width.
Now things get a little tricky. The main limitation of this exercise is that you're not allowed to draw lines all the way back to the vanishing point. That means this is going to take a great deal of estimation - which is why it's called the rough perspective exercise, not exact perspective.
Start with just one line, coming off one corner, and draw it back towards the vanishing point, but only as far as the length you wish to give this box. And don't cheat by making your boxes super long. We're not aiming for cubes here, so the length doesn't need to match the height or width of your rectangles from the previous step.
Again, use the ghosting method. Starting out by putting little points where you want your line to start and end will help, and ghosting all the way towards the vanishing point can also help you maintain your alignment with it (but of course you can't actually draw the line all the way back).
Now that all three dimensions of your boxes are established, it's just a matter of figuring out the rest of the puzzle. Place points on the page for the remaining three corners of the back of the box. Remember that your horizontal lines are still running parallel to the horizon, verticals are running perpendicular to it, and your depth lines are converging towards the horizon.
With all of this in mind, try to place your points on the page in a way that maintains all of these relationships. None of this is guesswork - there are specific rules and behaviours you follow, so if at any point you feel you're not sure what your next mark should be, step back and think about it.
Once you're done a whole page, grab a pen of a different colour, or a pencil, or something you can visibly separate from the rest of your work. Using a ruler, take all of your depth lines (those that are meant to converge towards the vanishing point) and extend them to where they intersect with the horizon.
We are not plotting these red lines back to the VP - just to the horizon line. This will show us a concrete idea of how far off we were.
There's a good chance that you'll find them not intersecting with it at the vanishing point, and you may also find that the further away your boxes are from the VP, the further off they are in their alignment. This is totally normal, and it helps a great deal to go over our work in this manner to help identify where our estimation of perspective tends to drift, so we know what to focus on during our next attempt.
The purpose of this exercise
This exercise is all about separating you from the explicit reliance on plotting everything back to your vanishing point and getting used to the fact that your parallel lines converge. Due to the nature of perspective, with the innumerable vanishing points that may be necessary in a given scene, we can't necessarily rely on all of them being explicitly drawn out, especially if we don't want to spend the better years of our lives plotting it all out. As such, there's a lot of value in learning about how the lines themselves behave on their own, as well as coming to appreciate the fact that often times "close enough" is more than good enough. Even though you've got mistakes in your estimations, the boxes still are likely to look pretty close to correct, and ultimately there are more important things than perfection when it comes to getting an idea across with visual means.
When adhering to a strict perspective system (one point, two point, three point), you immediately give up a fair bit of flexibility in terms of how the objects you're drawing will be oriented. For example, if everything is drawn according to the same two vanishing points, it will be as though everything was placed on a set grid.
There is a vast advantage to this however - because the orientation of objects becomes restricted, we limit the possible behaviour of every line to only a few options. Many students ignore this fact, however - they lay out their vanishing point(s), then assume they'll know by instinct how every line should behave. Instead of knowing, they guess.
If you ever catch yourself guessing or uncertain about how to draw a line, stop and step back. Take a look at the system you're working with, and think about the short list of possible behaviours. In one point perspective (which we are using for this exercise), you have the following behaviours:
All lines that go off into the distance converge at the vanishing point
All horizontal lines run perfectly parallel to the horizon
All vertical lines run perfectly perpendicular to the horizon
There are simply no other options. Every single line will adhere to one of these three behaviours. So, find which one matches the line you're trying to draw, and then apply it.
It is fair to say that in one point perspective, you can have lines that don't run parallel or perpendicular to the horizon, but - these rules are going to hold fast here however because for the purposes of this exercise, all of our boxes are going to run parallel to the ground plane, rather than being slanted or angled.
Mistake: Plotting lines back to VP
So the point of this exercise is to get used to visualizing the lines going back to the VP in your mind's eye, rather than actually drawing them on the page. So, instead of drawing those lines, you can work on your accuracy by ghosting the lines all the way back to get a good angle, then drawing only the segment required for the box you're drawing.
Mistake: Not using 1 point perspective
Every now and then I'll have a student submit work for this exercise that has more than one vanishing point. I want you to use only one because it allows you to focus more on the challenge of aligning your lines back to that one VP. Giving yourself multiple things to worry about isn't going to help you learn any quicker, it'll instead slow you down. As such, each exercise is designed with a strategically chosen set of goals.
This page has student-made recordings
They're great to draw along with, or just to see how much time these exercises really take when they're not rushed.