Above and Beyond

3D Isosurfaces

Once one has a firm grasp on the algorithm and idea behind Metaballs, applying the information acquired here is not too difficult to expand into the 3rd dimension. New difficulties are introduced, however, such as working with a space that we cannot practically draw on a per-pixel basis in (ie. we must use polygons/triangles), we need to define surface normals for, and other irksome challenges.

This unfortunately goes out of the scope of this article, but several helpful websites detailing some insights into 3D Metaballs are listed in the References section.

Isosurfaces in the Real World

As a brief aside, it's worth talking a little about where isosurfaces are outside of the numerous demos that showcase Metaballs. One prominent use is that a Metaball primitive is included as a tool or plug-in in many 3D modeling software packages like Maya or 3D Studio Max. Raytracers like POV-Ray also include functionality to render flexible isosurfaces.

Medical imaging is another area where isosurfaces see heavy usage, as it can be an efficient means of volume visualization (eg. MRI scans). Engineering also sees usage of isosurfaces as means of visualizing things like air pressure or fluid flow in simulations. (cite)

The Meta Playground

Available for download is my "Meta Playground", which allows for the manipulation and viewing of all of the meta-shapes covered in the article, plus a few extra aesthetic features.

Source code is available, and should compile on all major platforms.

(Playing with several Meta-Shapes.)

Download Meta Playground (Win32 Binary)

Download Meta Playground (Source Code CPP File) [No resources included; get from Win32 Binary]

References

The following websites were used for ideas and/or understanding of the theory behind metaballs, isosurfaces, and level sets, as well as some of their applications.

• Paul's Projects *First image in article included with permission from Paul
• Ryan's Balls
• Hannu's Plaza
• Wikipedia (Metaballs) (Isosurface) (Level Set)

If you have any further questions about metaballs or isosurfaces, or any comments regarding the article, please don't hesitate to drop him an email at stephen.whitmore (at) gmail (dot) com; he'd love to hear from you.