## 3D Realisation – Topology

Topology is defined as “the study of geometrical properties and spatial relations unaffected by the continuous change of shape or size of figures”. By definition, this is obviously a very important thing to consider when working with 3D models, as it clearly is very important to have an understanding of how polygons make up specific shapes and also how spatial relations effect the overall look of your model.

Before I attempted to work out the topology of some images myself, I did some research into the subject myself. Within 3D modelling, Topology can be defined as “The flow and organisation of edges on a given 3D model”. As 3D modellers, we are concerned with Geometric Topology, which studies manifolds and their placements within other manifolds.

One of the most important things that I have learned to remember (thanks to this research) when working with 3D models is that it is important not to ignore topology. This would cause massive problems further down the production pipeline. It is important therefore to be conscious of topology throughout the process. This involves avoiding N-gons (5+ sided polygons), as game engines are not able to calculate those kinds of polygons. It is also to model in quads wherever possible (keeping tris to a minimum) as game engines automatically attempt to triangulate polygons.

I also looked at some examples of models done by others, and noticed that all the edges which made up the model are set up in such a way as to define the shape of the model. For example, a curved line would be made up of several straight edges. See the following example.

3D Face Model (Notice that any curved areas are made from several straight edges).

To put these skills to practice, we were tasked with finding a Family Saloon from the 80s, a leather sofa and a celebrity/celebrity bust. With the images we found, we were to draw the topological data onto the pictures.

Here are the pictures that I chose.

Bill Goldberg – Ex-Professional Wrestler

Ford Escort

Worn Leather Sofa

The following are what I was able to come up with.

Bill Goldberg Topology Drawing – David J E Smith, 2014

Ford Escort Topology Drawing – David J E Smith, 2014

Leather Sofa Topology Drawing – David J E Smith, 2014

One thing you may notice is that there are quite a few curves in my drawings. In a real 3D model, these curves would be made of straight edges. You may well notice the odd tri polygon here and there too. It is important to remember that in an actual 3D model, some these would actually be quads as they would continue around the model in 3D space. I admit though that some of these tris may well be errors on my part.