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View Full Version : Help!! I have a modeling project due and I'm in a rut!!


Mrpearlzildjian
03-07-2007, 11:03 AM
I need help...and I can't even remember how to do a screen grab...yes I'm THAT rusty in Maya. So bear with me. I just finished modeling half an object, that I wish to duplicate to the opposite side to make a whole object symmetrical. Here's my problem: There is a nice big very noticable seam that I can not get rid off reguardless of what I've tried already. I've screwed with the normals time and time again, I've combined and merged verts, and it just will not go away!! I need some help on this one, I need to figure this out quickly because this project is due very soon!! Please help!!

Mrpearlzildjian
03-07-2007, 12:21 PM
Here is a screenshot of my problem -
http://i48.photobucket.com/albums/f205/Mrpearlzildjian/Ion_cannon_problem.jpg

I need these two pieces to be a single mesh, with no seams. How do I accomplish this?

OpenDut
03-07-2007, 12:25 PM
If you're modeling organic objects, then one suggestion I have is convert the current half of the mesh you have, to subdivision surfaces.

Then use your subdivision surfaces menu feature, called the "mirror subdivision" option in the subdivision menu to mirror your subdivision for you. I believe this is helps you to get rid of the seam.

Generally a seam is created because of discontinuous mesh, i.e. you have doubles (double vertices/edges/faces). If you haven't done so, maybe you could try increasing the merging distance a bit to ensure the vertices at the symetry line is merged.

Anyhow good luck.

Quosman
03-07-2007, 02:07 PM
I don't didn't do organic stuff yet, but I'd suggest to move the vertices at the seam and smooth or even render the window to see the results. you could also try to add another loop near the mirror axis and align the vertices of the new loop to the corresponding ones at the axis so they have the same height. hope this helps!

starving_artist
03-07-2007, 04:22 PM
Assuming that you are using Maya, i'd try this...

from the pull down menu go to Edit Polygons > Normals > Soften/Harden

from there you can use the slider or use the All Hard or All Soft buttons to make the needed adjustments. Hope that helps :)

glib
03-07-2007, 04:35 PM
I assume the two meshes have already been combined, and the verts have been merged.

It just looks like a hard edge to me. Make sure you're in the modelling module, select the edge, go to Normals > Soften Edge. Should fix it. :)

OpenDut
03-08-2007, 02:33 AM
That's what subdivision surfaces are for MrPearl

It smoothes your mesh. A smooth polygon mesh is not the same as a Subdivision surface mesh.

Here's an example. The left mesh is an unsmoothed polygon mesh, the middle mesh is the same mesh but smoothed, the third (on the right) mesh is a subdivision surface version of the same the mesh before.

http://img.photobucket.com/albums/v639/Ryu_Kaiser/unsmoothedExhaust.jpg

Notice how the subdivision version does not longer have any hard edges until you add more edge loops and bunch them up. Once you made your mesh a subdivisional surface mesh and have added extra edge loops to make hard edges, you will get results like this:

http://img.photobucket.com/albums/v639/Ryu_Kaiser/subsurfedExhaust.jpg

Quosman
03-08-2007, 07:30 AM
thats a good explanation OpenDut, but now I have a few questions: what are the advantages and disadvantages of using sub-d's over a smoothed poly-mesh? looking at your pictures, the resulting surface seems to be the same. workflow would be to model in hard poly and then convert to sub-d, or do you use sub-d's from scratch?

GregOconn
03-08-2007, 11:34 PM
What did you do to let yourself get rusty in Maya? tsk tsk :)

Can I see a wireframe of your model? There are a few things which could be causing your problem. Assuming you have already a) made sure your normals are facing outward, and b) softened your normals it could also be one of the two following problems.

A seam like that can be caused by two edges too close together. in which case its usually easiest to solve by selecting the undesired row and either deleting it, or using average vertices and using your normal move tool to move it back out and make it nice and rounded.

The other thing it could be although its harder to see unless working with the scene, is that you might have open edges along your seam. Go into your custom polygon display and turn on show border edges. This will help you see if your seem is inface a border or not. If this is the case connect the up and your away.

OpenDut is quite correct and I think his posts are great. But personally I stay away from subdivisions and prefer to use smooth/proxy. Try smoothing your model. Depending on what version of Maya you are using this will either be under the Polygon>Smooth menu or the Mesh>Smooth menu. It might be a good idea to try both the smooth and subdivision paths so you can make a personal decision of which works best for you.

Best of luck,

Greg

OpenDut
03-09-2007, 02:54 AM
thats a good explanation OpenDut, but now I have a few questions: what are the advantages and disadvantages of using sub-d's over a smoothed poly-mesh? looking at your pictures, the resulting surface seems to be the same. workflow would be to model in hard poly and then convert to sub-d, or do you use sub-d's from scratch?

Advantages:
- Smoother looking polygons, or more natural looking for organic.
- With Maya subdivision, you can use both polygon tools e.g. append polygon, cut face polygon etc AS WELL AS NURBS tools since Subdivisional surface is the combination of both. Well at least that's what it said in books.
- Smoothed - polygon mesh are not really smoothed, subdivisional surface are the proper way to smooth the mesh. Look at the CG artworks in the 3D choice gallery, you can be safe to say they're pretty much the majority is subdivisional surface e.g. Soa Lee's new picture.

Anyhow, here's what I mean by a smoothed polygon and a subdivisional surface. The bottom engine exhaust is just a set smoothed polygon mesh. The upper engine exhaust is a subdivisional surface of the same polygon mesh. Immediately, you can tell the difference between smoothed polygon vs subdivisional surface:

http://img.photobucket.com/albums/v639/Ryu_Kaiser/setsmoothvssubdivisional.jpg

More so, if you press the Smooth button in Maya for polygons, you need to create a more higher polygon mesh just to get that same smoothness than if you were to use a subdivision surface. Reason being as mentioned before is that Subdivision surface are both polygon and NURBS. It has the smoothness of NURBS and the easy to use polygon functionality. E.g.

http://img.photobucket.com/albums/v639/Ryu_Kaiser/MayaSmoothedPolyVsSubd.png

Notice how I have smoothed the polygon mesh (left) and it still isn't as smooth as the subdivisional surface version (right). Further more, the subdivion surface, as you can see, has lesser vertices than the smoothed polygon.

Disadvantages:
- Not suited for game engines.
- Takes longer to render than polygon only.

Workflow:

Well, those meshes were not created with Maya, except the one that showed the 3D viewport with the mesh. I use Blender as my choice of 3D software, but the idea still applies. If you're using Blender, then subdivision and polygon feels exactly the same because all we do is apply a subsurf modifier to our mesh and we can take it off anytime we like and it'll become a polygon again. No need to undo or anything, just a modifier.

For Blender, it doesn't matter when you use subsurface.

For Maya however, I tend to model the full thing in polygon mode first then convert it to subdivisional surfaces. This will help me get clean mesh (no n-gons, or triangles or very few of them if any) which the above example already shows. If you start to use subdivision surface at an early point, I can't guarantee you won't have n-gons in your mesh. Even the digital tutor guys start with polygon first, then they convert between subdivision later and polygon afterwards.

Quosman
03-13-2007, 10:35 AM
wow, thanks for the great info OpenDut! I'll definitely look into sub-ds with my next model!

GatorNic
03-14-2007, 01:02 AM
When using Maya I tend to stick with the different polysmooth methods. Also sometimes using a plugin like ActiveSmooth on a hotkey. Mainly because of maya's implementation of subdivision surfaces.

Other disadvantages of subd (in Maya, not to subd's in general):
-working with more complex models becomes agonizingly slow. The have sped it up a bit since earlier versions of Maya, but it is still pretty bad.
-There is no edge loop/ring selection in subd standard mode. So if you wish to use creasing or any editing once you move up to a "finer" subd level, you have to select every edge manually.

Don't know about Blender's, I haven't used it, but XSI's subd implementation is pretty awesome.

starving_artist
03-15-2007, 10:49 PM
just a thought, with the shape of that you are trying to achieve you could easily do a NURBS revolve. It would achieve the smooth look you are looking for and might also cut down on poly's if thats an issue.

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