Starting with your cylinders around arbitrary minor axes, there are two main issues that come up across the set that suggest an inconsistent understanding of some of the core concepts of how these cylinders should be constructed. These two issues are as follows:

• Cases where the relationships between the ellipse closest to the viewer and the ellipse farthest from the viewer are reversed

• Cases where you appear to be forcing the lengthwise-dimension's vanishing point to infinity, resulting in the side edges being parallel on the page and there being no scale-shift from one end to the other.

As noted in the instructions, as well as back in Lesson 1, there's two main things that "shift" as we side from one end of our cylinder to the other. There's the shift in scale that we get as a natural result of perspective, where the convergence of the side edges causes the ellipse on the farther end to get smaller overall. Then there's the shift in degree, where as the far end moves away from the viewer, it kind of "opens up", appearing wider to the viewer because of the change in the angle at which it's seen.

Now you definitely understand that both of these shifts exist, but I'm seeing a lot of cases where you've got them reversed. For example, if we look here at this page towards the end of the set, 144 is correct - closer end is larger in its overall scale, but proportionally narrower, and the farther end is a little smaller in its overall scale, but considerably proportionally wider. Compare this to 147 (as well as 145, 146, and 148), where we can't actually tell clearly which end was intended to be which. We get one end that is both smaller in its overall scale and narrower, and another end that is larger in its overall scale and wider.

As to the second issue, where you were eliminating the foreshortening from the cylinders and drawing your side edges as being parallel to one another, we saw this most of all towards the first third of the set. Eventually you did seem to pick up on the greater need for variation, but there definitely continued to be cases where you'd end up with parallel edges, but I suspect this may have ended up mixed in with the confusion resulting of the first issue as well.

These notes explain why this is incorrect - not just in terms of going against the instructions that requested a great degree of variation in the rate of foreshortening, but also in terms of this actually being incorrect in the greater context of linear perspective, since our cylinders are rotated randomly, and vanishing points only end up at infinity when the form in question is aligning in specific ways to the viewer's angle of sight.

Continuing onto the cylinders in boxes, these are definitely better, and you're holding to the instructions here more effectively, although there are some issues I wanted to call to your attention to ensure that when you approach this exercise in the future, you can continue to get the most out of it.

This exercise is really all about helping develop students' understanding of how to construct boxes which feature two opposite faces which are proportionally square, regardless of how the form is oriented in space. We do this not by memorizing every possible configuration, but rather by continuing to develop your subconscious understanding of space through repetition, and through analysis (by way of the line extensions).

Where the box challenge's line extensions helped to develop a stronger sense of how to achieve more consistent convergences in our lines, here we add three more lines for each ellipse: the minor axis, and the two contact point lines. In checking how far off these are from converging towards the box's own vanishing points, we can see how far off we were from having the ellipse represent a circle in 3D space, and in turn how far off we were from having the plane that encloses it from representing a square.

In applying the line extensions fastidiously and consistently, at least for the most part, you've armed yourself with the kind of analysis that can then be used to identify how your approach can be adjusted for the next page's worth, basically to bring those convergences more in line and result in a box that has those two square planes.

The main issue I wanted to draw to your attention is that this process isn't perfect, and it can result in some pitfalls if we're not careful. For example, if we look at 191, 192, 194, and 195 on this page, these are cases where the box itself probably wasn't drawn with the intention of having those square planes. While the square-plane thing is mentioned in the video, I don't consider this to be a mistake, nor do I hold it against you for not necessarily applying that aspect of it here.

What it can result in however is that the minor axis lines for our ellipses, which should be pointing down the length of the cylinder (so using 191 as an example, the minor axis line would be drawn in blue), but when the box gets really skinny in one dimension, this can actually flip the minor axis to point in a completely different direction. In that case, the minor axis line ends up matching the fainter red contact point line that extends up and to the right.

Now, if when you're drawing your line extensions you're colour-coding them based on the direction in which the line is extending, you might not notice the issue at all. If however you're going through them and thinking, "okay I'm drawing the minor axis line, which should be going down the length of the cylinder, so those line extensions are blue so I'm going to use blue for the minor axis line" - then you'd end up with a blue line grouped with your reds, and that will be more likely to stand out to you as a problem to be addressed. If however it's drawn with the same red as the other lines it groups with, you may never notice there was an issue in the first place.

So, be sure to keep that in mind going forward, so you can continue to get the most out of this exercise when practicing it as part of your warmups.

That said, due to the more significant issues pertaining to the first section of the challenge, I will need you to redo that section before I can mark this challenge as complete.