View Full Version : What is the DEFINITION of topology in 3D models?

10 October 2006, 09:01 PM
Hello there. I am currently a student working on a research on topology on humanoid models. A lot of people suggested me to look into this forum for usefull information, since this place appears to be a haven for 3D experts.

So this is it. I am asking your opinion for your technical definition of what topology is.
This is a two-scale question >>>

1) Topology on genaral 3D models.

2) Topology on 3D humanoid models.

If any usefull information come up that can be used in my research, CGtalks forum and its posters will be noted down and take credit for it in my presentation. :deal:

So guys, what is your personal view on the subject?

10 October 2006, 03:10 AM
Correct me if I'm wrong, but I believe topology is this:

The flow and organisation of edges on a given 3D model.

I don't believe the definition of topology changes relative to the model, instead only the way in which the topology is arranged.

Cheers :D

10 October 2006, 08:25 AM
do a search in the help files of any 3d app on:

Quad (4 sided polys)
Edge Loops
Non-Planar polys
Non-manifold geometry
5 sided polygons

basically for organic mesh you will want all quad using edge loops to define muscle and bone of the mesh. Edge loops function as defining the lines/curves/creases of an organic mesh. Also, it is important that all polygons have a similar density and size in the mesh for an efficient and accurate subdivision and deformation.

Hard edged modelling does not require such a strict modeling workflow but can still take advantage of edgeloops to help create a flow to the mesh. Because it is often not necessary to subdivide a mesh entirely, polygons can be disproportionate in size and local subdivision of the mesh is more effiecient. Also, if the mesh is not deformed in any way, this grants even more freedom to modelling the mesh in terms of a nonquad surface.

10 October 2006, 01:25 PM
I like this thread, happy you posted this question as it will lead to a lot of useful info :thumbsup:

Ok, literally, topology means topos, place and logos, study.
So I would say that the topology is the study of how to organize the parts of an object (a model, organic or not) in the space they occupy (their structure) so to obtain functionality and balance between themselves and the whole object. In CG that I suppose that would mean how to organize the structure and flow of edges, vertices and polys.

Wow, that was hard! Anyone good in maths/geometry good probably phrase this much better.
Hope this helps

PS: also found this simple definition on a notebook, cannot remember where I took it from though :)
"The relationships between surfaces in a solid model: for example, between loops, edges, and vertices."

10 October 2006, 11:29 AM
I want to thank everyone till now that tried to reply to this mind-puzzling topic.

I don't believe the definition of topology changes relative to the model, instead only the way in which the topology is arranged.

Actualy i think it does. When you model an odject, a chair for example, you only care for the chair to be visualy correct, whether in the case of a living creature topology has to be correct so the proper deformations appear when the model is animated. So, in the case of modeling creatures, topology defines the overal mass and muscular structure in combination to the flesh that covers it.

lol what did i just say? :shrug:

I think there is more to it than just that. Come on people, brainstorming time! :buttrock:

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10 October 2006, 11:29 AM
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