Technically it is no longer called CGI, it's just CG now.
Mainly because the term is beyond broad.
There is also the fact that alot of 3D Artists got pissed off with Pixel Artists claiming a sodding colouring was CG work.
Technically ya it's a Computer Generated Image, however unlike Rendering an Image (which is what alot of 3d artists believed the term was for) the Pixel Artist was actually doing the artwork.
Bah! Come to Siggraph one year, there is always and argument in a strip club or bar about it early evenings.
In order to create the images you'd need a program which is capable of rendering.
Lightwave, trueSpace, 3D Studio Max, Houdini, Maya, Softimage|XSI, Cinema4D, POV-Ray, SolidRender, Rhino3D, Nendo, etc...
There are alot of modellers and render engines out there.
Just be glad your not doing it for a living, Maya has 32 different Rendering engine... Best are Menal Ray / Messiah / Renderman, but alot of the others offer some good things so you find yourself researching and playing alot of the time.
Problem with CG Rendering are a few things...
a/ It takes talent, but looking at alot of game CG nowadays, not as much as there used to be. Well cept for Shenmui3, but those guys had $150mil to play with... i'd expect those kinda results lol
b/ High-End Creation Machine. Rendering is intensive, but creating high polygon scene is just as hardcore on your system.
I would recommend a Pentium 2.5GHz w/QuadroFX 500 256MB AGP8x w/512MB Ram w/21" CRT DVI-Model, bare minimum!
c/ Beyond what you can afford Render Server or better yet a Farm.
Rendering a 2,000,000 Polygon Scene, single pass, just Shadows and Lighting... on the machine above your looking at the better part of an hour to render.
Movie Quality CG can have anywhere between 200-900million polygons per scene. Usually you take multiple passes because it is quicker rendering bit of stuff than it is rendering an entire scene in a single go. This is a technique you would have to learn like the back of your hand, understanding what to render in what pass... then how to combine it.
Remember a single image at 45min might not seem to bad, but lets say you wanted to make a 5minutes CG Animation.
That 300seconds, which you then take an multiply by 30 (NTSC)... so your looking at rendering out 9,000 Frames, each at 45minutes. So ya you'll be rendering for atleast 2-3months solid hehee
Hense the need for a Server Render or a Render Farm.
Technical skills enough for a Render Farm is what i'd recommend, however most Farms will hold around 16-20 Server Slids, each one of them will probably set you back the price of a mid-range PC.
Not to mention the cases themselves for them are usually close to $3,000.
d/ After experience. You have to understand how to put together the frames you've rendered, not only this but you really have to be thinking about most of this prior to even opening your modeller usually with a short storyboard, concept sketches and design notes on how things will be transitioned.
Shake and/or Adobe Premier become your weapons of choice.
Shake is awesome, but will most likely also require a Mac to edit with. Not sure if there is a Windows version, never used or had the need for one.
Neither of those products are cheap either.
e/ your looking at ALOT of man hours. Usually what happens is, each guy/gal on the team has thier own thing to do. Suchas a single character, or a squad of similar characters, or the world around everyone, or the background, etc...
So usually it allows moer focus on each thing. I've seen some good things from people on thier own, however this is only from people that believe thier good when really you cat coughs up better looking things or they were blessed with skill you wish you had.
put simply, CG is something best left to the professionals.
luckily there are number of professional houses that don't charge an arm and a leg, you could always bother some 3d art student who wants something for thier final thesis project.
Generally try and get your hands on someone who knows what they're doing and has access to the hardware/software required.