When Good "Lost" Titles Do Bad Things: Part II

Mark mentioned that because he's watching Lost in HD now, the visually flawed title intro that I wrote about two years ago is bothering him too. He asked for a technical reason why these render gaps occur so here it is.

The NURBS curves used to create the 3D text are mathematically perfect and completely smooth but the problem lies with the construction of the extruded text as well as what happens in the final render. To speed up render times, most 3d applications automatically convert these perfectly smooth NURBS surfaces into tiny triangles. Because triangles are flat, if there are not enough of them, the edges start to look faceted. What compounds the problem is that in order to render the front of the text, artists usually create what is called a trimmed surface. This creates a discrepancy between the geometry of the front and the geometry of the sides. When that happens unsightly trim gaps usually appear.

So how do you fix it? The easy way is by brute force. You simply adjust the tessellation of the extruded text by adding more triangles. Because increasing the tessellation requires more memory and longer render times, these larger tessellation values are not set by default.

At Gnomon, because of these rendering artifacts as well as other issues with animation, we were never allowed to use trimmed surfaces in our classes and had to use a method of NURBS modeling that I would describe as painful at best. This is probably why so many artists prefer polygonal modeling. NURBS does have it uses though!