From the last article, I have briefly discussed about the topological requirement and the types of topology error that commonly found in a 3D game model. Then, there comes a string of questions from my fellow students:

“How do we detect these mentioned topological flaws in our model without our naked eyes?”

“Is there a shortcut to detect N-GON (by default)?”

The answer is “YES”; there are automated ways to detect topological error for polygonal mesh in Autodesk Maya. Nevertheless, from my own practitioner standpoint, “You will keep making the same topological mistake, over and over again, if you can’t even identify these primordial errors of your own creation by naked eyes.”

Although having said so, sometime it does absolute necessary to use these automated detection approaches when you are working on a quite complex character mesh, or being assigned to edit and “clean up” other people’s model that you are not familiar with.

Detecting Holes or Gaps (unmerged/unweld vertices)

First, I would like to share with you how to detect “holes” or any unmerged vertices via the following YouTube Podcast. The holes or “gaps” it is a common mistake that most junior practitioners would tend to make when fusing different form of polygonal objects as one single solid mesh. The following demonstrated method uses the function of Custom Polygon Display (CPD) to detect any unmerged vertices.

Besides using the function of CPD, you can also detect holes by toggling between the hardware smoothing preview (or display) function in Maya viewport. For instance, to detect the gaps that found in the following polygonal plane, you can hit the keyboard numeric key of “3”, as any polygonal surface that had gaps will not flow together under the condition of smoothing. After done identifying these problematic regions, you would need to hit the numeric key of “1”, for returning to the default hardware display setting.

Detecting Gaps & Holes for unmerge vertices

Such gap-detection approach of switching between two different hardware display settings is quite fast, as it only involved the switch between the numeric keys of “1 & 3”. However, it can be quite messy at a time with its overlapping mode of wireframe display if compare to CPD approach, which provides us the defined outlook of the problemmatic areas. Besides that, the CPD approach can help us to identify the texture border as well when we are in the stage of UV Unwrap & Layout planning.

Detecting N-GON

Next, to detect any N-GONs on your game mesh in Maya, we would make use of the function of Cleanup. To learn how to apply the Cleanup function in your work, let us look at the following demonstrated example:

Cleanup N-GON Detection

  1. First, select the polygon mesh that you would like to inspect.

  2. Then, go to the menu of Mesh > choose Cleanup. This action will prompt us to the default Cleanup Options.

  3. In the options-window, simply reset its operational settings by checking on only the:

    “Select matching polygons”
    “Apply to all polygonal objects”
    “Faces with more than 4 sides”

  4. Lastly, simply just click on the “Apply” button, and you shall see the all the N-GON faces been automatically highlighted. From there onwards, you make use of the interactive split polygon tool for fixing all the N-GON surface.

Again, this suggested workflow is to help you to identify any N-GON faces in your model and you have to make the fixes by hand. Alternately, should you have switched the operation setting from “Select matching polygons” to “Cleanup matching polygons”, this Cleanup operation will turn to automatically fixing all the detected N-GON faces, by triangulated the mesh. Both types of the operational settings have its pro and cons, as the first one would give you the full control for complying to some strategic planning, whereas the other automated settings suite well under the no-brainer conditions.

Besides detecting N-GON, the Cleanup function can help us to detect other topological errors such as non-manifold and non-plannar polygonal faces as well. So, be wised and learnt to make a good use of the CPD and Cleanup functions. Hopefull, this article would help you to craft a game model that is topologically perfect!

#end