As a whole your work here is honestly very well done, although there are a few points I want to call out to ensure that you continue to get the most out of this exercise going forward.

So when it comes to what we're doing in this exercise, the most important thing is recognizing that, as noted in these reminders from Lesson 2's texture section, this is an exercise that involves understanding the nature of the textural forms we're dealing with, and then applying that understanding to make our own decisions. One of the biggest mistakes students make is thinking that it is a purely observational exercise, and so while sidestepping the main focus of the task itself, they also find themselves in situations where how successful they feel they are ends up being entirely dependent on how well suited the reference they've chosen is to (their misunderstood version of) the exercise. That can result in a lot of frustration.

Fortunately for the most part you've been making a lot of clear and intentional decisions here, so you don't appear to have fallen into that trap. The trap isn't binary however - you're not either in it or out of it. Rather, it's more of a spectrum and many students still benefit from having the above spelled out, even if they were doing it largely correctly already.

So, as noted in the reminders, it comes down to three things:

  • Observing the reference to identify the textural forms that are present, how they're arranged, along the surface, and also identifying whether there are different "levels" of texture (for example, a brick wall can be seen as having the bricks themselves as being the only textural forms - but if you look closer, you'll notice that there's also a rough texture to the individual bricks, made up of little textural forms of their own).

  • Understanding the reference - meaning, thinking about the textural forms you've identified as they exist in 3D space, and how they relate to one another. This also means separating that information from how it is visually represented to you in the reference image, where it is also impacted by a specific light source in a specific position - something we may wish to change for the purposes of our own gradient study.

  • Transfer that understanding to the page - not visually, but spatially. The marks you put down on the page may differ from how the texture is represented in your reference (especially if you end up having to change the light source to fit the exercise, where our light source is always coming from the far right, and also if your reference is of anything but a top-down view of a flat surface, you'd have to consider how it'd be seen from above, and how it would change if the texture were applied to a flat surface). In this phase, every mark we put down is a cast shadow shape, first outlined, then filled in, as everything we convey to the viewer is through the specific design of these shadow shapes, which conveys to the viewer the relationship between the form casting the shadow and the surface receiving it.

For the most while you didn't adhere to all of these elements perfectly, you were more in line with doing it correctly than not, but I still want to call out the notable discrepancies from this:

  • For your first texture, the pomegranate's insides, it seems that for the most part you laid out the forms, but then focused more on filling in the negative space between them with black. This resulted in shadow shapes that were not the result of thinking about the relationship between the casting/receiving forms/surfaces, but rather something else that is more arbitrary.

  • In a number of other cases, like the dried lava, ice cream, old bark, cauliflower, the wolf furs (and notably much less so in the textures after that point), you tended to lean into drawing individual strokes one at a time. This approach, which I tend to describe as "painting stroke by stroke" robs you of the opportunity to specifically think about the design of a single cast shadow shape, which means you aren't thinking as much as you could be about the spatial relationships involved and letting them drive your decision making. I suspect this may have been a big part of why you struggled with that rope initially, and why when you came back to it at the end, you handled it a bit better - although I should note that here you've got a mixture of cast shadow coming in from the right side of a given column of rope, and form shading on the left side of a given column of rope. For the purposes of this exercise (and really anything in this course), skip on the form shading and focus only on cast shadow.

Based on the fact that you did indeed consistently have your light source placed on the far right, you may already understand this completely, but I often share the following with students as part of my texture-focused critiques, so I figured it wouldn't hurt to include this in case it helps solidify your existing understanding: as shown in this diagram, depending on how far the form is from the light source, the angle of the light rays will hit the object at shallower angles the farther away they are, resulting in the shadow itself being projected farther. This is at the core of how we're able to create these gradients, as it means that the shadows at the far right are extremely small, but gradually deepen until they start spilling into one another to create large "compound" shapes. In those areas the shape of the individual cast shadows still matters, because it's how we correctly establish the shape of the large shadow they fuse to create.

The last thing I wanted to share is to do with any texture consisting of holes, cracks, etc (so like your cracked desert and to a lesser degree, the craters). it's very common for us to view these named things (the grooves, the cracks, etc.) as being the textural forms in question - but of course they're not forms at all. They're empty, negative space, and it's the structures that surround these empty spaces that are the actual forms for us to consider when designing the shadows they'll cast. This is demonstrated in this diagram. This doesn't always actually result in a different result at the end of the day, but as these are all exercises, how we think about them and how we come to that result is just as important - if not moreso.

Speaking of the craters, I did admittedly find it a bit odd that the size of the shadow being cast into the crater (from its rightmost edge) seemed fairly comparable in size to the shadow cast to the left of the crater's leftmost edge. That would imply to me that the craters are shaped more like this, with a large mound on the left side, and no mound on the right side. Ignoring the fact that the farther structure from the light source would inherently get a somewhat larger shadow, the shadow being the same size tells us that the distance from the top of the structure casting the shadow to surface receiving the shadow would have to be equal, which as far as I understand it would require this kind of assymetrical mound-on-one-side to be achieved.

That may well have been intentional, but if it wasn't, the leftmost edge would have at most a small shadow, but even that is only if it rises above the surface to the left of it.

Anyway, as a whole you've done quite well, and as you continue to work to apply what I've raised here, you should be able to make effective use of this exercise on your own. I will go ahead and mark this challenge as complete.