Sure, I understand, they seem like interchangeable terms. But the thing is there are inevitably going to be *similarly* named things in any program. Or things that do similar things or look similar, but *are* different (a good example in Terragen is a sphere and a planet). Sometimes the differences really are so subtle that they require in-depth understanding, and missing that sort of thing is an unfortunate but inevitable part of the process of getting better at a particular application, but sometimes you are simply trying to move too quickly, and make too many assumptions.
In this case I think it's a useful learning moment: look carefully at the color coding of your nodes, it has important meaning. Gray nodes are Object nodes, and the Rock is an Object. Red nodes are Shader nodes, the Fake Stones is a Shader. They work completely differently in the scene. They are also used in different parts of the node network. These are differences that I think you would have noticed if you'd looked a bit closer, but I imagine you were more focused on trying to figure out how to use the clip file you'd gotten. The thing is that this kind of basic information that is communicated through the software is a very useful *part* of figuring out how to use something. Take the time to see the info that the system is communicating to you and it will at the least let you know how to ask the right questions, if not tell you the answers in itself.
I hope all this doesn't sound patronizing. We all overlook simple things sometimes, and the answer is usually just to slow down, look carefully, and act with deliberation and intention. We want to help you when you have problems, but it makes things harder when you aren't able to ask the right question.
Now, in answer to your original question, you can change some Population parameters on a per-axis basis, like object spacing and spacing variation. Scale doesn't work this way, but it should be a relatively random distribution of sizes within the range you specify. If it doesn't appear to be so, it's likely an issue of perception, i.e. larger stones are more obvious and seem more prevalent because smaller ones make less visual impact. It *could* also be a bug of some kind, or a "random" distribution that isn't sufficiently random. But I would sooner suspect simple perception bias, which is common.
In any case I'm not sure use of a Rock population is best for your needs (not yet sure what your needs really are though). If all you really want to do is figure out how to use this clip file, then that's fine, but if you have an end goal in mind perhaps you could describe that or provide examples. In many cases Fake Stones are an easier, faster way to achieve a good "rocky" result.
- Oshyan
