Optimization for a 3D model

Two things that video game artist should do. The first one. All 3D model have hidden polygons. I mean polygons that no one can see them. It’s important to remove all of them, because for each one, the 3D engine has to do operations. With less hidden polygons to compute, less operations faster the engine runs. Just below you have an example of hidden polygons:

Base of the house

You can see in the image above the structure of a house seen from the base. We remove the base polygon because, surely, the house is going to be over a terrain, and nobody will see the base polygon. This trick can be done in many places of a model obtaining this way an optimization.

The technical specifications of a graphics cards say that they can compute millions of polygons per seconds. It really means triangles per second. The triangle is the basic calculation of geometry of any polygon. The polygon we removed before, was formed by four vertex, which means at least two triangles. Although we only see a polygon, the graphic engine computes two triangles. If we have more than four vertex the number of triangles grow.

With lots of polygons, these are lots of calculations for the engine. Bad thing. To reduce the number of triangles is something difficult. But we can do the calculation work easier for the engine, and here comes the second thing that should have been done by an artist. For a graphic engine it’s very expensive to compute long triangles -for example a long base and a short hight-. These kind of triangles can be avoided by using the tool ‘Turn’ of 3D Studio Max.

The tool 'Turn'

This tool shows you all hidden triangles and allows you to choose the best hypotenuse of the triangles, turning the hypotenuse in all possible ways with different vertex. The hypotenuse is drawn with a dotted line. The tool is very useful specially when you cut over a polygon, because this operation generates new triangles that you don’t see and could affect the efficiency.

Walls of the house

Then, here you have one more reason to remove hidden polygons. Because you aren’t leaving a polygon, you’re leaving at least two triangles that we didn’t think were there.

Introduction to modeling

These first weeks of the master, we have two types of classes: design and art. Daniel Sánchez Crespo, the Novarama founder, he teaches design. The art class is given by an artist from Novarama. In art class we start with 3D concept:

• Modeling a geometry
• Mapping, to give texture to a geometry
• High detail modeling
• Textures
• Materials
• Lighting
• Particles system

The objective of this stuff is to know how artists work. We’ve started with 3D Studio Max 2008. At university I had done a class about it, but I only remember a few things. We started with modeling. As introduction, we created a simple chair, we drew the texture and we put it on the chair. Up to now, everything OK. After the chair the difficulty level changed. And the rhythm is now fast.

The original model of the house

We are creating a house from a model already created. See the photo above of the original model -when I’ve finished mine, if it isn’t too bad, I’ll show it-. The look is awesome, with real textures, normal mapping and a great lighting. We are supposed to follow the professor’s instructions, but some times I got lost. Too fast. Thankfully, in the next class the professor repeated some steps and I assimilated the basic concepts. Everything was better. Anyway, I think that to be a good artist, of any kind, you have to have some innate ability.

The professor recommended the work of Andrew Loomis about drawing, you can find it free on the web. Also, he recommended a book called Modeling a character in 3D Studio Max by Paul Steed. To end, some interesting links about computer graphics:

• CG Society
• Gamasutra
• Polycount