WHAT IS THIS 3D STUFF, ANYWAY?

One of the lapidary designers that contributed to the site, asked me "Just how does this 3D stuff work, anyway?" This page will serve as a quick introduction to the world of 3d art for those visitors that aren't aquainted with it, and show how I went from a diagram of a real stone to a virtual model.

 

3d art consists of two main phases:
MODELLING and RENDERING.

 

MODELLING

Modelling is the (mathematical) construction of an object, by defining points in a 3 dimensional array. This array is based on the X, Y and Z axis of geometric space. Then, different sets of these points are mathematically 'joined' by lines, to create polygons, and the polygons joined to create objects. The simplest result is usually displayed as a wireframe model.


Wireframe model.

In some program, this display might show as a plain solid shape.


Plain 3d display.

At this point, the model is considered to be 'made', but not rendered fully.

 

RENDERING

Rendering may or may not occur in the same program that modelling does.
In order to fully render an object, certain properties must be assigned to it, and to the surrounding 'environment'. For an object, some of the properties may be transparency, color, reflection, refraction, or specularity. (There are others properties, as well. How many depend on the progam used and the complexity of it's render engine.) The sum of these properties tells the program how that object 'looks' in relation to it's environs. The above "Plain 3d display" is a render, but the properties are the most basic: white color, opaque, no background to interact with. The only unseen things are the lights which illuminate the different sides of the object.

In the next example, the cube object has transparency, reflection and refraction settings applied, and is set into an environment with another object (a black cylinder) and over a colored ground plane.


Render with properties assigned to
objects, and to environment.

Once the properties are set to the artist's stisfaction, the program then calculates -for each and every pixel of the desired display area- what would be visible based on the sum interaction of all objects and their properties. The following animation shows a render in progress.


Render animation.

But how did I make the gem models? I started with 2d images (many found at Bob's Rock Shop and at the AFMS design archive) Here's an example of one:


GemCad output image.

In my modelling program (I used TrueSpace, but there are others out there), I imported this image as a background and began by constructing a 16-sided polygon (as this gem had 16 sides in the top view). Then, I 'lofted' the polygon into a 16-sided cylinder

Then, by manipulating the various points, edges and polygons, I began producing something closer to a gem.

The final result hopefully matches the 2d image I started with.

The smaller versions visible are extra views that were set to match the top and side views from the 2d image. Once everything matched up, I had a 3d object ready for rendering. For personal preference, I use a program called Bryce for rendering. The Bryce presets, mentioned in the "Materials" section of this website, are simply pre-calculated properties for different stones, such as ruby and diamond. I simply assign those to the object and began the render.

After that, it's merely a matter of deciding how to use this model in a scene.

Still have questions? Write me. I'll be happy to help out and share my interests in both 3d and lapidary arts.