Hello Esteban90, I'll be the teaching assistant handling your lesson 4 critique.

Starting with your organic forms with contour curves there is something to call out, it seems you did one page of contour ellipses, though the assignment was for both to be contour curves. Not a huge problem, but it does suggest that you may want to be more attentive when reading through the instructions.

Your lines look smooth and confident, which is great. You're not quite sticking as closely to the characteristics of simple sausages that are introduced here as you were in your lesson 2 pages for this exercise. When technical exercises are reassigned in later lessons it is important to take the time to review the exercise instructions to make sure you're following them as closely as you can, instead of relying on your memory of the instructions.

So, we're aiming for two balls of equal size, connected by a tube that has a consistent width. here on one of your pages I've marked with a green check mark where you're reasonably close to this. Forms marked with an A have one end significantly larger than the other. Forms marked with a B are swelling through their midsection and becoming bloated.

When we place an ellipse on the end of a sausage form, it's actually no different from the usual contour curves, aside from the fact that we're conveying the fact that this particular end is facing the viewer, allowing us to see the whole way around the contour line, rather than just a partial curve. I noticed on some of your forms you'd placed them on ends which the preceding contour lines suggest are pointing away from the viewer. I've marked on your work with a cross where you'd drawn an ellipse on an end facing away from the viewer. I also added a missing contour ellipse to an end that faces towards the viewer. Take a look at this breakdown of the different ways in which our contour lines can change the way in which the sausage is perceived - note how the contour curves and the ellipses are always consistent, giving the same impression of which ends are facing towards the viewer and which are facing away.

I can see you've included some variation in the degree of the contour curves on some of your forms. Keep in mind that the degree of your contour lines should be shifting wider as we slide along the sausage form, moving farther away from the viewer. This is also influenced by the way in which the sausages themselves turn in space, but farther = wider is a good rule of thumb to follow. If you're unsure as to why that is, review the Lesson 1 ellipses video.

Moving on to your insect constructions overall your work is coming along very well. You're showing a good understanding of how the forms you draw exist in 3D space and connect together with specific relationships and most of your constructions feel solid.

Normally I spend some time explaining to students how to differentiate between the actions we can take when interacting with a construction, which fall into two groups:

1 Actions in 2D space, where we're just putting lines down on a page, without necessarily considering the specific nature of the relationships between the forms they're meant to represent and the forms that already exist in the scene.

2 Actions in 3D space, where we're actually thinking about how each form we draw exists in 3D space, and how it relates to the existing 3D structures already present. We draw them in a manner that actually respects the 3D nature of what's already there, and even reinforces it.

Here in your work you're already taking the majority of your actions in 3D space, which is fantastic. I'm still going to make use of a piece of prewritten text that lays down an important rule to help you to take actions in 3D, as we would like you to continue to do this in the next lesson.

Because we're drawing on a flat piece of paper, we have a lot of freedom to make whatever marks we choose, but many of those marks would contradict the illusion you're trying to create and remind the viewer that they're just looking at a series of lines on a flat piece of paper. In order to avoid this and stick only to the marks that reinforce the illusion we're creating, we can force ourselves to adhere to certain rules as we build up our constructions. Rules that respect the solidity of our construction.

For example - once you've put a form down on the page, do not attempt to alter its silhouette. Its silhouette is just a shape on the page which represents the form we're drawing, but its connection to that form is entirely based on its current shape. If you change that shape, you won't alter the form it represents - you'll just break the connection, leaving yourself with a flat shape. We can see this most easily in this example of what happens when we cut back into the silhouette of a form.

Fortunately you don't cut inside the silhouettes of forms you have already drawn very often. I've highlighted in red here on some of your legs where you'd cut inside the silhouette of your sausage forms.

I've highlighted a possible occurrence of this in red on this spider. If we consider the manner in which you've drawn the fur texture on the abdomen there, it implies that you've used the inner line of your ellipse to represent the silhouette of this form. This leaves the other line of your ellipse floating outside the silhouette of the construction, reminding the viewer that they are looking at lines on a flat piece of paper.

Where there is a gap between passes of an ellipse, treat outermost perimeter as though it is the silhouette's edge - doesn't matter if that particular line tucks back in and another one goes on to define that outermost perimeter - as long as we treat that outer perimeter as the silhouette's edge, all of the loose additional lines remain contained within the silhouette rather than existing as stray lines to undermine the 3D illusion. This diagram shows which lines to use on a loose ellipse.

Instead, when we want to build on our construction or alter something we add new 3D forms to the existing structure. Forms with their own complete silhouettes - and by establishing how those forms either connect or relate to what's already present in our 3D scene. We can do this either by defining the intersection between them with contour lines (like in lesson 2's form intersections exercise), or by wrapping the silhouette of the new form around the existing structure as shown here.

This is all part of understanding that everything we draw is 3D, and therefore needs to be treated as such in order for both you and the viewer to believe in that lie.

You can see this in practice in this beetle horn demo, as well as in this ant head demo You can also see some good examples of this in the lobster and shrimp demos on the informal demos page As Uncomfortable has been pushing this concept more recently, it hasn't been fully integrated into the lesson material yet (it will be when the overhaul reaches Lesson 4). Until then, those submitting for official critiques basically get a preview of what is to come.

You're doing a really good job of working by adding complete 3D forms in a lot of places. Sometimes you do make an addition to your constructions without quite providing enough information for the viewer to understand how that new addition exists in 3D space. Here is an example, where the legs on the far side have been chopped off, they cease to be complete 3D forms, and instead they're just partial shapes. A form doesn't cease to exist in 3d where it passes behind another object, so it is really important for developing your spatial reasoning skills to "draw through" and complete your forms, even if it is partially obscured in the reference.

The next thing I wanted to talk about is leg construction. On the majority of your pages you've done a pretty good job of using the sausage method for constructing legs. It's not uncommon for students to be aware of the sausage method as introduced here, but to decide that the legs they're looking at don't actually seem to look like a chain of sausages, so they use some other strategy.

The key to keep in mind here is that the sausage method is not about capturing the legs precisely as they are - it is about laying in a base structure or armature that captures both the solidity and the gestural flow of a limb in equal measure, where the majority of other techniques lean too far to one side, either looking solid and stiff or gestural but flat. Once in place, we can then build on top of this base structure with more additional forms as shown in these examples here, in this ant leg demo and also here on this dog leg demo as this method should be used throughout lesson 5 too.

You're doing a good job of laying down your sausage armatures, and establishing how the forms connect together using a contour curve at the joints, well done.

When it comes to building on these sausage structures, there are a few places where you'd added a little bit of extra complexity with a single line or partial shape. As shown here we can build these extensions with complete 3D forms instead.

I can see plenty of places where you are adding to your leg constructions with complete 3D forms, although there are some approaches to building up structure on top of those base sausage armatures that work better than others. While it seems obvious to take a bigger form and use it to envelop a section of the existing structure, it actually works better to break it into smaller pieces that can each have their own individual relationship with the underlying sausages defined, as shown here. The key is not to engulf an entire form all the way around - always provide somewhere that the form's silhouette is making contact with the structure, so you can define how that contact is made.

Your textural work is quite pretty, but unfortunately there are some ways that it is deviating from the instructions on how to handle texture in this course which are introduced in lesson 2. ThatOneMushroomGuy discussed how to think about texture in this course during your lesson 3 critique, so I'll ask you to go back and reread his eloquent explanation on the topic. Of course if anything said to you here, or previously is unclear or confusing you are allowed to ask questions.

Some of the issues I'm seeing are as follows:

• Using hatching lines to create form shadows. As discussed here we do not include form shading in this course. Here are some examples on your work.

• Using hatching or solid black to indicate areas with a darker local colour. When we use texture in this course we're using cast shadow shapes to implicitly describe the smaller forms running along an object’s surface. We're telling the viewer how that surface feels if you were to run your hand along it. This has nothing to do with what colour that surface happens to be.

• On this construction you also appear to be outlining the shape of highlights.

It is important to set aside any personal expectations you may have for how you want your homework to look. Remember that these constructions are exercises, and in order to get the most out of them you should follow the instructions as closely as you can. I suggest you review these reminders on texture to refresh your memory.

All right, you're showing a strong understanding of the concepts taught in this lesson so I'll go ahead and mark it as complete. Please keep the points discussed in this critique in mind as you work through the next lesson, as they will apply to animal constructions too.