There are a few different ways of doing 3D objects. Most of them are made up of meshes. A mesh is like a wire construction for a model in which the skin (texture) is applied. Like creating those paper mashe sculptures in school. A mesh has to have enough detail to show every contour within a body that you wish to show. You can get high and low resolution meshes for either closeup or distant images. The higher the resolution the mesh is, the more resources your computer needs to do its rendering.
To start with there are static meshes and animated meshes. Other meshes are created on the fly from formulas like fractals. These are often used to create plants and structured forms.
In the old days all the artists used to create their own meshes for producing images. This was a very large job and meshes got more and more complicated. Nowadays, there are mesh builders, morphers, skin experts, texture designers, clothing designers, hair experts, animators, compositors, artists and many other expert areas.
I grew up in the period where every scene started with nothing more than a camera and a ground plane. It is much easier and much more flexible and fun nowadays.
You, as an artist can now either find or buy many of these items to create your own images without all the long hard worque of days gone by. Morphing
The thing that is very unique about modern meshes is that they not only can animate and move with near correct muscle movement, but can alos be modified to look completely different. For example, the people meshes that I use are used for both skinny, fat, realistic, cartoonish and many other styles. What this means is that the designers of these meshes have made is so that if it is fat, then you will get bulges, love handles and saggy fatty areas... while the exact same mesh
can be made skinny and have the ribs showing in the exact same area that used to have bulges.
This is nearly more complicated than real life.

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Of course, not all meshes are equal. Many don't allow this flexibility but are instead great for animating.

Getting started.
People and animals came into my images as static meshes originally.
Later I started to use a software package called Poser (I thinque I may have actually started at Version 1).
Poser gave you a man, a woman, a boy, a girl and a couple of animals. Within Poser you could move all the arms, legs, fingers and bodies of these meshes. You alos had the ability to apply expressions, some blobs of hair and a few other static shapes. Some fundemental clothing was alos available to dress them ready for thier snapshots.
It was often very difficult to get you figure posed in a natural manner (but boy was if fun trying). Eventually once you have a pose, you can save that pose or scene and then use it again later.
If you want more detail on how to use Poser I will write a tutorial about it.
Getting even more.
Once you are comfortable with Poser, you can extend your horizons.
A site I came across is site called DAZ3D. This site is selling a different mesh (they now give it away). This mesh is called Victoria 3.
There is alos Micheal 3, Stephanie 3, David 3 and quite a few others, like The Girl. There are teens, children, babies, many animals, animal
packs, dinasours, birds and all the accessories.
These figures allow you to morph them into many different styles. Fatter, skinnier, super skinny, pregnant and so many more. You could even change the
Victoria into a man. Be aware that most morphing packs are purchased seperately.
Once you are done morphing, you can then animate them or just render them in still images.
The amount of things that you can buy or get for free is now very extensive. There are many props that can be used within your images. Be aware that anything defined as a prop cannot be posed or animated.
I may do a tutorial on Using DAZ products later, but half the fun of it is finding it all out for yourself.

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