View Full Version : What is sub-d's

07-03-2006, 10:14 PM
I look at the pdf file and I hear the chat press tab to make things sub d's ok I am still a noobie and things look softer when sub d's are on...so what are they?:screwy:

07-03-2006, 10:26 PM
Kind of hard to explain, but it is a process to help make organic objects. If you create a square and hit tab you would end up with an almost ball. Still kind of squarish, but definite rounded corners and edges. By applying segments near the edges will flatten out the side, one way to do so is to use the bandsaw tool. Using weightmaps is another way to control how round or flat a side is.

07-03-2006, 10:40 PM
way over my head. I will try to post a audo file with my question heh.

07-03-2006, 11:40 PM
Maybe this example will help.

07-04-2006, 12:33 AM
Subd is short for subdivision surfaces. LW variant is called subpatches/metanurbs, which produces something simular to the CatmullClark algorithm, which is the most common variant. It looks about the same but doesn't do ngons (polygons with more than 4 points/edges). When you turn them on LW will subdivide each polygon into several tiny ones and also do a smooth operation on them. You can set how much LW should subdivide from the General Options panel ('o'). If you lower the subdivision level and look closely on a surface without surface smoothing you should be able to make out the tiny polygons.

If you need more info, just do a search online for subdivision surfaces or catmull-clark.

07-04-2006, 12:53 AM
If you're a complete beginner all of the above might be confusing so I'll try and make this as simple as possible! :D

When you create a cube in LW you can choose to subdivide it (shift - d) if you choose the metaform option it also smooths it, makes it more rounded, less angular. The problem with that is that you end up with many points, if you want to adjust the shape you might have to move dozens of points which takes time and is difficult to keep smooth. What subds (subpatch) do is make the object look as though you have subdivided while retaining the low polygon information. The advantage is that if you're modeling a very complex shape like a face you can adjust it's shape by moving a small number of points instead of hundreds (maybe thousands!), lightwave will smooth out the shape automaticallly.

Hope that makes sense! :D

07-04-2006, 03:04 AM
Just gonna throw in my two cents:

One way to look at it is that the two models, polygon and sub-d are two totaly different calculationmodels (although you build a sub-d as a polygon model).
If you hit tab, Lightwave changes to a differend calculationmodel. It changes to a curve or spline model in wich the vertexes are the control points. By changing the position of the vertexes you control the shape of the spline/curve (you can also weight the vertexes to change the curve).
If you transform this calculationmodel to 2D (in your head) it looks very much like b-spline modeling, only in 3 dimentions.

Look at the 'using b-splines' video (3th video from the top) in this link to see how b-splines work. Lightwave does the same but then in 3D with sub-d modeling.


07-04-2006, 07:38 PM
"Hello fyborg_1138 it appears that you have not posted on our forums in several weeks, why not take a few moments to ask a question, help provide a solution or just engage in a conversation with another member in any one of our forums?"... Why yes mister computer program, yes I will...:help:

Welcome to Sub-Ds, fellow noob, here's a sub-division primer (http://www.subdivisionmodeling.com/wiki/tiki-index.php?page=What+is+sub-division+modeling) to help all of us with our noobishness (is that a word?). Hopefully the site helps answer all of your (our) sub-D questions, queries, ponderings and what-have-you.


07-05-2006, 07:05 PM
ah ok. All the information has been good information. I was going to ask that since sub d's smooth stuff out is that the best way to model. Its clear that the answer is no. So when I am working on objects its best to leave off sub 'd or rather turn them off and on to see from time to time how I am doing. but you should not model in sub's. This is how new I am.

In any case Thank you for clearing up sub D's and showing the videos.