On a computer game how much Kb or Mb does a 3D computer generated object take-up?

Question

I am not sure how to ask this question or know if anyone will understand the question but, how much space or measurement does a 3d object take up-up? For instance: One pixel takes-up about 66K-bytes and one symbol(letter "a") takes up 1bit or one byte. I can't remember at the moment.
If anyone understands what I am talking about please help me.

I am trying to make a 3D computer game. I want to know so that I know how big I can make a "digital world" in my game.

Answer 1

Impossible to say, without knowing how many vertices / polygons it uses and how big is your coordinate system (i.e. how big are the numbers). Also, a 3D object can also have surface textures, which are extra from the 3D wireframe data.

Just design it without worrying about the details. You can always trim it down later.

Answer 2

In a 3D game, an object is described by a series of vertices, a list of the connections of those vertices (surfaces), and the textures that the graphics engine maps onto the surfaces. A tetrahedron, for example, has four vertices, which require (for example), four four-byte coordinate values. So, make that 16 bytes for the vertices.

The list of connections contains six elements, each a pair of four-byte numbers, so that's another 48 bytes.

So far we're up to 64 bytes for the raw data. If you want to draw simple, flat triangles, then you have all the data you need already, less a little overhead for actually getting to the information and managing it. For textured objects you'll need some amount of RAM for the texture, but I couldn't tell you how much that would be because it depends on whether the texture repeats, etc.

That's just for one four-sided figure.

The fact is, how much memory you need depends on how big the world is, how many things are in the world, and how many surfaces those objects have.

By the way, 1 pixel doesn't take up 66 kilobytes. 1 pixel takes up four bytes in most 32-bit graphical systems (RGBA, that is). The letter 'a' takes up one byte, unless it's a real 3D object, in which case it takes up a lot more space, depending on how well it's rendered.

Answer 3

Generally, there is no set amount of memory that a 3-D object takes up.
It all depends on how the program compresses its data and how smooth it makes its curves (or in your case, the # of polygons you use to make those 3-D objects) A modeling program like Autodesk Inv. 11 makes very smooth 3-D curves and an object like a simple toroid (a doughnut, basically) can use up about 80 Kb. Other objects, like a cube, use as little as 10 Kb.
The graphic quality will make a huge difference as well. Do you want your ""digital world"" to look like it was made for the N 64 or the PS3?
No matter what you choose however, most standard desktop computers aren't equipped for such large amounts of 3-D graphic generation!