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mjm
09-07-2002, 02:12 AM
Thought I'd post this here. I don't think it deserves a full-blown tutorial, just because it's so elementary (yet still fun).

While I was surfing around, I saw a tip on Flay (by Ronald van Vemden) about how to subdivide n-gons using the Legacy plugin, MetaformPlus. I remembered this plugin from quite a while ago, and thought I'd do a little experiment with it for local detail. Now, a little bit of modeling philosophy here (this is info picked up from guys like Bay Raitt, John Feather, etc.). In the 3d world, you have your basic triangles, quads, and then beyond that what are commonly regarded as n-gons. That is, a polygon with n-number of sides. You'll often hear about people preaching to "religiously stay with quads" and "avoid triangles/n-gons at all costs." The reason for this comes about because of a process known as polygonal refinement. Lightwave, I believe, has its own proprietary smoothing algorithm, but it is still similar to other algorithms brought about by guys like Catmull and Clark, Doo and Sabin, as well as Chaikin. If you do a google search on these guys, you can read about the mathematics behind what are often referred to as "Subdivision Surfaces." In each of these algorithms, basically the number and positions of the sides and vertices of a polygon are counted, and then average vertices/edges are created. If you have a quad, then, the average vertex will be located in a position where you won't have any skewed polygons as a result. However, what happens if you have a 20-sided polygon? The algorithm will try to put the center vertex at equidistant, but you're going to have not only skewed polygons, but also what are referred to as polar vertices as a result. With a polar vertex, you have more than 4 edges coming into that vertex. As a result, movement of that vertex will cause smoothing to become erroneous as the smoothing algorithm tries to figure out what to do with the surrounding polygons. This is where you get creases, bumps, etc in your mesh that are just plain annoying. You can avoid such vertices by using a smart topological layout of polygons, thus allowing 4 edges to come into each vertex and proper morphing to occur.

Now, we can actually use n-gons to our advantage, as long as we stay away from polygons with say, 100 sides. Try smoothing one of those - in any application. :) People are always trying to get a lot of detail in their models, and often use tools such as EdgeTools from Dstorm, Bandsaw, Bandglue, SmoothShift, etc. This little schpeel uses those, but also the MetaformPlus.p plugin that can be found in your "legacy_plugins/modeler" folder. So here we go (due to lack of creativity, I'm just using a basic shape similar to one of my older models. I like big mouths and small eyes. Don't even start with that perverted stuff ;) ):

1) So here is just a basic box with two smooth shifts down the Z axis. Symmetry is on. Then I cut two edges along the z-axis, and one along (and aligned to) the y-axis, and pulled some points around (Figure 1 (http://mywebpages.comcast.net/djmcchesney/Quickdetailtut/1.jpg))

2) I hit Tab to turn Sub-D's on, then just pulled some points to round out the form. The outer edges were moved in, leaving those aligned with the y-axis to push outwards (Figure 2 (http://mywebpages.comcast.net/djmcchesney/Quickdetailtut/2.jpg))

3) I smooth-shifted the 4 polys at the front in a few times, and scaled those to create an oral cavity. I also pulled some of the vertices surrounding the mouth around to reduce any pinching due to my lazy smooth-shifting (Figure 3 (http://mywebpages.comcast.net/djmcchesney/Quickdetailtut/3.jpg))

4) Alright, here comes the fun part. I could use smooth-shifting to start the eye-sockets and the area around it, but I thought I'd try a new little method. Thus, I selected the 2 quads on top and closest to the mouth and used SHIFT+D set to Metaform to create 8 new quads. Now, this creates n-gons surrounding these 8 faces (those are the non-existant faces you can see through). What will we do with those? They're like high school kids, always causing trouble. (Figure 4 (http://mywebpages.comcast.net/djmcchesney/Quickdetailtut/4.jpg))

5) I deselected everything, then ran MetaformPlus on the object. This cleared up the n-gons, and once I went back into Sub-D mode, I was left with a ince little mesh. It's not topologically wonderful, but with some spinquadding, that can easily be fixed (I won't go into that right now..that's a separate schpeel). (Figure 5 (http://mywebpages.comcast.net/djmcchesney/Quickdetailtut/5.jpg))

6) After selecting 4 quads on each side of the head, I smooth-shifted these, then rotated, then smooth shifted again. Pulled some points to stop creasing due to lazy rotating, and as a result I was left with a start for eye sockets. (Figure 6 (http://mywebpages.comcast.net/djmcchesney/Quickdetailtut/6.jpg))

7) By smooth shifting and then scaling down, we start to get our basic form for what this is going to look like. (Figure 7 (http://mywebpages.comcast.net/djmcchesney/Quickdetailtut/7.jpg))

8) Smooth shift again, move back, scale, and refine some of the edges to create a some eye-sockets. Figure 8 (http://mywebpages.comcast.net/djmcchesney/Quickdetailtut/8.jpg))

9) Now just a little bit more detail and refinement. I accidentally forgot to undo a bandsaw I did around one line of polys around the lip, thus you'll notice some extra geometry between the eyes (the loop goes around the mouth, between the eyes, and under the model). However, I selected the inside loop, smooth shifted that, then pulled out the lips and refined a bit more. (Figure 9 (http://mywebpages.comcast.net/djmcchesney/Quickdetailtut/9.jpg))

10) And finally, I thought I'd give him a tongue, so I smooth-shifted out 4 quads at the back of his throat and continued doing so. Scaling and smooth-shifting, as well as refining the overall shape of the tongue. I also fixed some of his mouth cavity, pulled it in some, etc. The phantom-selection really helps. Oh! Also, if you want to constrain movements in Perspective, just hold down your middle-mouse button. It takes some getting used to, but helps when you want precision moves. (Figure 10 (http://mywebpages.comcast.net/djmcchesney/Quickdetailtut/10.jpg))

And there you have it, a little friend that can keep you company. Well, in my case, my only friend :p This can be applied to larger models where you want to add small micro-bumps, etc, without having to go in and manually create your edges and kites, etc. Just watch your topology. If anything, this serves as a starting point for refining edge loops, etc.

Hopefully that wasn't too simple, and the intro wasn't too long. Sorry if it was either of those. I'm thinking about doing a tutorial that would actually be worthy of being posted in the Tutorials section...so... keep your eyes open :p

Underwurlde
09-07-2002, 02:14 AM
cheers Marc, I'm gonna do this tommorrow, ummm ... too drunk tonight!

LyonHaert
09-07-2002, 03:29 AM
wow, that's pretty nice. thanks, i've learned several new things tonight :)

wgreenlee1
09-07-2002, 03:53 AM
Excellent!!!
This metaforms legacy .p is going to come ine really handy.
Thanks!

dies-irae
09-07-2002, 08:41 AM
you end up with more polygons than using boring edgetools/splitting techniques, but it's so much easyer and less timeconsuming that it's really worth a try!!
thx!
:bounce:

DigitalDeuce
09-07-2002, 02:16 PM
Submit that to NewTek -- mainly Proton.

That should go up on the tutorial site.

proton
09-07-2002, 02:22 PM
I was watching TV when I heard an Echoing TUTORIAL.......send that my way and we can get it online.....thanx!

mjm
09-07-2002, 06:36 PM
Alrightio, will do. I was thinking of putting together a more complete presentation though, before I send it. Maybe a bit more in-depth and complex explanation of modeling techniques/philosophy, some more example models, maybe a timelapse. School is starting soon, so it may take some time to get it all together - hopefully it'll pan out though :)

proton
09-07-2002, 06:37 PM
Take your time...I look forward to getting it online whenever you are ready....

jecal
09-07-2002, 08:24 PM
Originally posted by Marc McChesney
Alrightio, will do. I was thinking of putting together a more complete presentation though, before I send it. Maybe a bit more in-depth and complex explanation of modeling techniques/philosophy, some more example models, maybe a timelapse. School is starting soon, so it may take some time to get it all together - hopefully it'll pan out though :)

woohoo ... a timeplapse would kick ass but please if possible include the full gui :)

Many thanks ... :thumbsup:

Regards,

jecal

DigitalDeuce
09-07-2002, 10:08 PM
and not sooooo time lapse, if you're gonna do it that way.

Text and images would be fine though.

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