Boolean Poly Surface

[yoav-eytan]

Hi All,

I have a Poly Surface that was created by importing an OBJ file into Maya. When I'm trying to use Boolean command Between this Poly Surface and a new Polygon Primitive the two objects just disappear.
Can somebody suggest a solution? The imported Poly surface cannot be created with Maya since it's a real world topography created in Sketch Up and/or Rhyno.

Thanks a lot

yoav

[gmask]

I really need to sticky something about booleans..

The booleans in Maya are finnicky.. you cannot use them extensively to model with.

You need really clean geometry and the normals of the tool and die need to pointing in the same consistant direction.

[joojaa]

QUOTE(gmask @ 12/11/07, 09:12 PM) [snapback]277906[/snapback]
The booleans in Maya are finnicky..

Booleans on polygons are no matter what the propgram is as the problem is not only the boolean succeeding.

Would a faq entry be better?

[gmask]

QUOTE(Joojaa @ 12/11/07, 12:40 PM) [snapback]277913[/snapback]
Booleans on polygons are no matter what the propgram is as the problem is not only the boolean succeeding.
Would a faq entry be better?

I dunno seems like I have used programs in the past that failed much less at performing booleans.

FAQ entry is fine but I still think we need to sticky A READ THIS ABOUT BOOLEANS post in new user and the modelling sections.

[yoav-eytan]

Thanks for your responses. As I understand it's a mission impossible, and I should try and look for a more creative solution. If the second reply was referred to me, I didn't understand it at all.

Yoav

[yoav-eytan]

Here is the thing:
How do I assign parts of an existing Poly Surface terrain on the top of some kind of Primitives (Nurbs or Polygons), so that the top of the Primitives will have the shape of the original terrain and that the other facets of the Primitives will remain straight?

Your help is essential

Thanks

[gmask]

QUOTE(Yoav Eytan @ 12/11/07, 12:49 PM) [snapback]277916[/snapback]
Thanks for your responses. As I understand it's a mission impossible, and I should try and look for a more creative solution.

We can only speculate about the condition of the geometry being used to perform this boolean operation. In general is your mesh is a snarl of triangulated spider webs it won't work..a t least probably not in Maya.

If you cannot get the boolean to work then you could manually split polys along where the two objects intersect and then merge edges.. this is of course tedious work.

If you need animated booleans then you need to make sure your mesh is very clean.. again I have no idea what you mesh is like so ...

[gmask]

QUOTE(Yoav Eytan @ 12/11/07, 12:55 PM) [snapback]277918[/snapback]
Here is the thing:
How do I assign parts of an existing Poly Surface terrain on the top of some kind of Primitives (Nurbs or Polygons), so that the top of the Primitives will have the shape of the original terrain and that the other facets of the Primitives will remain straight?

If you are simply putting the terrain on top of a cube then use the cut tool. If it's a cylinder then from over head I suppose you'd have to use split poly tool, delet ethe extraneous faces and then snap the verts to the primative's top edges or something.

[yoav-eytan]

I will try that and comeback with the result. Anyway you were right about the structure of the mesh. It's an endless filed of triangles.

[gmask]

try running quadrangulate on it and then manually clean up any questionable areas or use polygon cleanup

[yoav-eytan]

I guess I need a more detailed explanation about Cut Tool (I can't find the command for Polys) and about the Quadrangulate. If you are not available to do so, can you refer to tutorials on these subjects?

[gmask]

Edit Mesh> Cut Faces Tools

It draws a straight line that you can position from different views and it cuts through all the faces selected. You'll probably want to select extract cut faces in it's options and then afterwards delete the parts you don't want.

Mesh > Quadrangulate

Will try to determine which faces could be quads and then deletes the unneeded lines. It has some options.. just mess around with it.

[yoav-eytan]

O.K, we are going somewhere... Is there an Intersect Command parallel for Polys? One which will draw an Isoparm along an intersection between two Polygons.

Thanks a lot for your support

[gmask]

QUOTE(Yoav Eytan @ 12/11/07, 01:45 PM) [snapback]277926[/snapback]
O.K, we are going somewhere... Is there an Intersect Command parallel for Polys? One which will draw an Isoparm along an intersection between two Polygons.

there is one for nurbs which doesn't help in this case

[joojaa]

Ok the problem in maya (and POLYGON BOOLEANS) is this:

Maya assumes the user knows what hes doing, this includes cheeking for the boolean sanity. However boolean is a operation that works like reality does. Polygons don't really work like real world does.

Now the polygon boolean works if you can satisfy the condition of trueness, and right ordering of data. For example max power booleans does those check before they proceed to boolean and force trueness on the object before going to next step. However its a bit questionable, it works off course but the problem is this:

If i allow the boolean function to arbitrarily fix the geometry at hand, is ist then the geometry i wanted to operate on? If so the user atleast minimum needs to indicate so. The problem is not so much that you cant do a solid check its that its impossible to ensure its the right one, you can guess. (guesses are cool as long as they work but when they dont...)

Now default maya backup for a unworking connection is no output + warning. This is becase the computer cant KNOW what to do with the data. Now the geometries didn't disappear, they just aren't shown to you anymore because the boolean should be there instead. Its like a html page that has a unknown item its just skipped or a warning is shown is its defined as strict html conformance (exact same kind of situation wiahc is also why XML is ALLWAYS STRICT).

But the boolean will allways work if you satisfy the border conditions of whats true, and have a maya native vertex order (this is easy to fix, and only applies very sporadically to maya objects but mostly to imported ones).

All this said theres a bigger question at stake tough, than getting the boolean to work! And that is what the hell does the boolean produce? I mena a polygon surface is something that looks like something but does not REPRESENT it. Now if we boolean accurately 2 things that Are not what they seem we get something that is even more not what it seems and probably don't seem that way eitrher.

PS will write the faq tonight. But really it should be a article since i will need pictures.