Cross section tool and shell modifier ala 3D Max in Maya?


#1

Hello everybody…

I recently switched from using 3D Max to using Maya while i’m doing a year abroad at school (design/architecture). So far I have really been loving Maya, especially with regards to modelling, NURBS is particularly awesome in Maya.

However I have run in to a couple of modelling issues where I find myself missing some of the old and easy to use Max tools and modifiers. Since I work mostly with architecture and design something I often need to do is add thickness to walls, casings, sheet-metals etc. With 3D max this was done relativly simply by adding the Shell modifier (which also provides you with easy shading due to material ID’s for back, front and side parts). In Maya I have basically either been offsetting the surface (if it’s Nurbs) or selected all faces and extruded in the normal direction (for poly’s). However extruding the faces in this manner does not equal a uniform extrusion unless the mesh is faily dense and/or planer (because it extrudes in a per face normal). Here is an example :


(The text says before extrusion and after extrusion, in Danish :slight_smile: )

Of course the other option is to stick with Nurbs (offset the surface and loft between the two for thickness), however this is kind of a hassle and creating a nice fillet/chamfer on the edges where the surfaces meet is super tricky with Nurbs (in my experience any way, if you have a good technique please let me know).

Another modelling issue i’ve been banging my head on is creating sections for say floor slabs etc. In 3D Max there is a tool that let’s you generate a spline section through any geometry by basically placing a plane where you want the section and hitting go. Then you can take the spline section and extrude it or add the shell modifier for thickness. All fairly easy and straight forward! Something like this would be super useful for my Maya work-flow?

I’m sure that Maya is more than capable of doing both these things (so far one of the things that has impressed me the most about Maya is exactly it’s flexibility), so please help me out and enlighten me. It would be greatly appriciated :thumbsup:


#2

Unfortunately nothing in Maya is really designed specifically for the sake of accurate architectural modelling. There all base modellings tool and the ones that are specially designed are done more for character modelling, or just freehand (no-measurement) modelling of structures.

The easiest way I found to create buildings that are properly measured is to create the floorplan in curves. Draw it all out in curves, wall thickness and everything. Then use the bevel plus tool and it can take a rather intricate flat closed curve and extrude it up and make caps on the top and bottom. As long as you don’t touch or do anything to the model right after running bevel plus on it, then you can reliably use booleans. So I would then draw in all the doors and windows in 2D close curves right on the floorplans, then bevel plus them, combine all the doors/windows into one mesh, then select the mesh that has all your walls, then select the mesh that has all the doors and windows, then go booleans>difference and it will automatically cut out all the walls and doors. If you apply the proper materials to everything before boolean, it will take them into account when it combines them.

As for the extrusion not maintaining the same thickness around corners, thats just how it works. The maya extrusion tool is not a face offset tool, it extrudes the vertexes directly along their normals with no special calculations, that is why it works the way it does.

Personally I’ve found architectural modelling in Maya to be just a bad idea all around. Sketchup is the way to go for architectural modelling, it is designed specifically for rapid architectural polygon modelling of buildings and it is by far the best for it. There is alot of things you can’t model in sketchup, anything organic or anything that isn’t generally building-ish sketchup will not be able to model efficiently. But you can just model those things in Maya and import them to sketchup. This is the workflow I currently use, all the building and building details I model in sketchup, this process is atleast 30% faster than doing it in maya if not more. Changing the model in sketchup is also far faster and easier to do than Maya, so when the structure is going through the design phase and the client is making lots of change, having the model in sketchup saves a ton of time.

Then for more intricate non-building-ish details and objects, I model them in maya, export the object and add it to my sketchup object library and then just drag it into the sketchup model. Alot of architectural firms are also adopting sketchup, so its a good thing to know anyways if your going into architecture.


#3

it looks to me like the face normals are not pointing in the same direction, across all the faces. Choose Normals -> Conform to fix that, and then run the extrude again. Though, the extrude will merge the verts where faces meet and put them at their average position, wich will not keep the distance correctly.


#4

Great info, rygoody. Once in a blue moon I have to do architectural stuff and your workflow should speed things up considerably.


#5

Hellow AHD,
In Maya the curve offsetting is pretty good for achieving this kind of uniform extrusion for a profile. Then you can generate polys from curves without much hassle, and retain great flexibility.

 Here’s an example how to achieve this. 

Draw a curve with the EP curve tool in a ortho view defining the profile of the shape from your before example.
Choose Edit Curves > Offset Curve and pick the Show Manipulator Tool (hotkey t) to adjust the offset or just type it in the channel box.
Select both curves, choose Surfaces > Extrurde > □, and in the Options window from the default settings change to:
Distance for Style
Polygons for Output Geometry
Quads for Type
General for Tessellation Method
Per Span # of iso params for U and V type
1 for Number U and V
Apply the settings (these are one time settings that you can reuse by just choosing the Extrude command every time after that)

 Use the Show Manipulator Tool (t) or the values the channel box for the length of the extrusion

In order to bridge the two surfaces properly, first you need to reverse the normal direction of one of the surfaces that is facing the other surface. To see the front and back sides of surfaces, and keep track of this for polygons and NURBS easily in general, uncheck Two Sided Lighting from your viewport Lighting menu. The back sides will be shaded black.
You may also need to choose Normals > Harden Edge to display this even clearer.

 Select the surface that faces the other one, and choose Normals > Reverse. 

Select both surfaces and choose Mesh Combine
Choose Edit Mesh > Bridge (you can change the divisions in the channel box after applying the command or before that in its options)

Now you can modify the geometry by sliding vertices along edges and at any time choose the original curve and move its CVs to redefine the profile.

  Hope this helps

#6

Hi again guys, thanks a lot for your input. It was really useful, thanks for taking your time to reply.

Emil3d - The bridge tool and the way you described is actually pretty much what I needed. It also works really well when offsetting amorphous Nurbs surfaces -> converting them to poly’s -> bridging. Your’re tip on the Show Manipulator Tool and the easy way of viewing normals-direction was also spot on. Cheers on that one :thumbsup:

rygoody - Thanks for clearing up the issue on the extrusion, i was’nt aware of exactly what it did so that really helped. The rundown on the bevel plus tool rocked as well, cheers.

I hear what you’re saying with regards to Maya/Architecture and to some extent I totally agree. Sketch-up and the likes are really easy and accurate. However it comes short when dealing with more complex geometries, think architects like Gehry, Asymptote, Coop Himmelblau, Zaha Hadid, Nox, Gregg Lynn etc. Furthermore I’m exploring the use of emergent systems and animation techniques within architecture and design as part of my masters. So I really need a more complex and flexible package like Maya for this purpose. Check out these websites for some examples of what i’m talking about (not my work BTW):

http://www.illu.at/span/index.html
http://projects.csail.mit.edu/emergentDesign/genr8/index.html
http://www.asymptote-architecture.com/

– Now how about that whole creating a spline section tool as described in my first post, any takers on that one? Any help would be highly appreciated, i’m thinking that maybe there is a MEL script or somehing that might be able to do the job!


#7

Another way is to make a duplicate surface and expand the faces using the sculpt geometry tool by a consistent amount using the flood command. Then connect the two meshes together.


#8

To create the section cuts, I think the only way is use the cut faces tool. It can pretty reliably cut a straight line through alot of complex geometry. It won’t put caps on the edges of the walls where you cut, so you’ll need to go through with the fill hole tool.

     and even if your doing abstract architecture, I wouldn't cut sketchup out of your possibilities. Sketchup has the most reliable and usable boolean system of any package, this alone makes it highly more efficient for any type of building modelling over Maya as you'll probably discover Maya booleans are unusable for modelling buildings because once a shape starts getting too complex, maya booleans can't work on it. Unless you maintain fairly simple geometry, you won't be able to just go through and cookie cut holes in walls with the Maya booleans, making holes becomes a very manual process. And really, the only abstract architecture sketchup will struggle on is where you would need something like a NURBS loft or bi-rail. Everything else it will do better than maya, it will especially do better on abstract architecture thats composed of many odd-angled flat surfaces as you can allign the axis to any surface and every tool will run off that axis. Maya, only the move tool will obey custom axis. Also, when you need lofting or bi-railing, can just make the surface in Maya and import it to sketchup.... and I imagine a set of good lofting tools in sketchup probably isnt more than a few version away.

#9

hominid - Pretty damn clever stuff there, works like a charm. Cheers and thanks :thumbsup:


#10

The sculpt tool flood option is definitely better than the Poly Extrude but the only perfect offset Maya can do is with curves and with Poly Extrude with Keep Faces Together OFF which in practice is pretty useless since the extrusions are chopped.
Even NURBS surfaces can’t offset perfectly if the surface doesn’t have a consistent width and height along its U and V parameters.

The following illustration shows the capabilities of the different methods. The same cross section was used to generate geometry with the different methods.

 [img]http://i111.photobucket.com/albums/n129/Emil3d/OffsetMethods.jpg[/img]

#11

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