Welcome back! As a whole, throughout this challenge you've done pretty well, but I have a number of suggestions that should help you continue to get the most out of this exercise going forward, and should also help further develop your understanding of texture as a concept, at least as we regard it here in this course.

There are three main issues I'm going to talk about, and not all of them are necessarily always present. In some cases you'll handle things better, but in some particular textures the way in which you think about the problem may shift in small ways, due to the slight differences in the circumstance, or even simply being in a different frame of mind.

So the first point we're going to talk about is the transition of dense to sparse in the gradients. In the instructions, we're told to put a solid black bar on the left, and a solid white bar on the right. You've certainly done this, but the extent to which you've applied the purpose of these bars definitely varies across the set. The aim is to create a smooth transition from that black bar into the actual texture portion, to the point where it blends seamlessly into the texture, making us unable to identify where the black bar ends and where the texture begins.

There are some cases where you've certainly done this - for example, the ice cream texture in number 19. There are others however - like the avocado in 21 where we can definitely see a very sharp cut-off where that black bar is.

To put it simply, you need to really push that transition further, and instead of limiting it to just the far left edge of your texture, try to start drawing the cast shadow shapes for your texture in its center, forcibly pushing yourself to make them broader and deeper as you move to the left. Remember - the shadow a form casts is actually quite flexible. You can think of it in terms of a sundial - if the light source is right above a given form (like the sun at high noon), then the shadow it casts will be very small. But if the sun is much farther away, like the sun being on the horizon at dusk or dawn, we get much longer, exaggerated shadows.

This diagram illustrates the concept - I also have this alternate version which illustrates the same thing, but with a different type of form.

The second point I wanted to talk about is to always remember that we're always working with the shadows these textural forms cast, not their outlines. You've done really well in this regard in a lot of these, but there are two that stand out - the rice in 13, and the reptile skin in 15 - where you're definitely working backwards from outlines. That is to say, you try to think about the outline itself, then add little gaps in those outlines. At the end of the day you're still more or less outlining the forms, because the marks you're putting down are not necessarily the shadows those forms would cast.

Be sure to give these reminders from Lesson 2 a read, as they explain the process in which we need to actually think about the forms we're drawing, and how we derive the marks we then go on to draw. I also have another example of this here which demonstrates that same thinking process (where we first identify the forms we want to imply, then individually design the shapes of the shadows they're casting, and finally filling them in.

As an off-shoot of this point, remember that since we're always drawing cast shadow shapes, you should not be relying in any kind of hatching to attempt to create mid-tones, as we see in the pangolin scales in 7, the curly hair in 17, and the rope in 24. Every mark is a cast shadow, and every cast shadow is a designed shape. Avoid putting done one-off lines, unless you have a very specific reason for it.

The last point I wanted to talk about is a specific type of issue we can run into with certain kinds of textures. Basically, anything that focuses primarily on holes or cracks - so for example, the mushroom texture in number 6, the cracked stone in 23, and the tree stump in 25.

The issue here is that because the bulk of these kinds of textures focuses on the cracks, or the holes, in their surface, we tend to perceive those cracks and holes as being the textural forms in question. But they're not - they're merely the negative space in between the textural forms, with the actual forms in question being the walls surrounding that negative space, which in turn cast shadows upon one another, and on the floor at the bottom of the holes.

Here's a diagram that should summarize how we can go about thinking through these kinds of textural issues, in order to always ensure that we're working with cast shadows, and not simply filling the negative spaces in. As a rule, in most cases a cast shadow you draw will require you to design a completely new shape, rather than simply filling in one that already exists. That shape will be what defines the relationship between the form casting the shadow, and the surface receiving it, in 3D space.

And that about covers it! You've made a lot of good headway with this challenge, and I expect the three major points I've raised here will help you continue to direct those efforts. I'll go ahead and mark this challenge as complete.