What Is Mesh Type

[f117f117f117677]

hey guys:
i have learned maya for times and i know the polygon, nurbs, subvision type.
but i am still confused about mesh, what is mesh?

is it abstract type , what's the differences between mesh and polygon.

any help would be appreciate.

[joojaa]

QUOTE(f117f117f11 @ 09/26/07, 10:08 AM) [snapback]273870[/snapback]
is it abstract type , what's the differences between mesh and polygon.

nothing, mesh is just the shape taht contains polygons, a polygon is just one face of a mesh!

[f117f117f117677]

QUOTE(Joojaa @ 09/25/07, 11:25 PM) [snapback]273872[/snapback]
nothing, mesh is just the shape taht contains polygons, a polygon is just one face of a mesh!

thanks,
and you mean mesh is a shape node, the polygon object has the mesh shape node?

[joojaa]

Yes. A polygon is one face. Thats why the menu for polygonal menu editing is known as polygons in plural, And a unit of many polygons is a mesh. Also why the menus containing poly tools is called mesh.

[fortner_mike]

I think a mesh is just another name for "object" or "body". Mesh is a mesh, and it can be made out of anything you like, polygons, nurbs etc...

[f117f117f117677]

QUOTE(thirt33n @ 09/27/07, 08:03 AM) [snapback]273972[/snapback]
I think a mesh is just another name for "object" or "body". Mesh is a mesh, and it can be made out of anything you like, polygons, nurbs etc...

can nurbs have mesh, please give me an example.

thanks.

[joojaa]

No,

Mesh = shape which contains many polygons. Thus all polygonal objects are meshes! And yes one shape contains just one unit of things.

shape is the generic name for a container. But do read on, term object does not exist in maya (outside of programming). What you most people consider objects are a combination of 2 dag nodes.

a shape parented to a transform.

there are several shape types, the shape type that contains polygons is a mesh type , which contains curves is a nurbsCurve type, a nurbs surface is a shape of type nurbsSurface, a subdivision surface is a shape of type subdiv. a camera shape type camera and so on for a quite long list.

A polygon is one face of a mesh! Just like you were taought in primary school. Its all mathemetics terms.

It would be quit restrictive to think a pair of transform shape as a object since theres so many configurations that wouldn't classify as anything. Such as a trasform with many shapes (a group is a transform with many transforms in same restrictive thinking)

The reason it done like this is because you need to be able to transform containers, and it would be a waste of time to develop same code over and over again. Thisway you can develop one new transform type or shape tye and use all the other existing types under or as parent of one.

[dryo]

Just to clear any confusion, a NURBS shape is not the same as a mesh shape. It's a collection of vector curves between vertices. Compare to a mesh shape, which has only straight line edges between vertices.

The confusion arises because NURBS get tessellated into triangular meshes in order to be displayed and/or rendered.

So, although everything gets converted to polygons at the display/render stage, NURBS tessellation is totally adaptive. Mesh tessellation is only adaptive inasmuch as Maya automagically divides n-sided polygons into triangles.

[fortner_mike]

Doesn't look like you're getting it, so i will try to put in in the simplest words that i can think of. Take a dictionary and translate the word "mesh" into English (if you are not from england or US that is). As you can see it has a similar meaning to words like "Object" "Body", maybe even "thing". So a mesh is any kind of object. Its just a name for all objects. For example, a Ferrari and a Volvo, are both called "car", so is a box and a ball both called "mesh". Right?. Mesh can refer to both 3D objects on your computer, as well as things from the real world.

Now NURBS, polygons and subdivision surfaces are the things that 3D objects are made from in a computer. So, a"mesh" (object) can be made out of any of these, and it will still be a mesh. Mesh doesn't really mean anything, and it doesn't have any influence on your workflow, it's just a name that we use to make it easier to communicate...

P.S. about that NURBS, Subdivision and polygon thing....they are al actually polygons, just manipulated differently, but that's something you shouldn't be concerned with just yet.

[thanasis_scifi]

Terminology is a good thing when you are trying to communicate specific information, therefore, a WORD is a container of a meaning, but a TERM has a specific meaning, and you can't look it up in the dictionary when you want to find what it conveys in 3D.

So, NO, NURBS are NOT meshes, you may think that, but maya ( and the rest of the 3D World) will not agree, you would know that if you had ever written a script that has to select something specific --like a mesh -- and do something to it.

Nurbs get tesselated for the render and the hardware display, so they appear like polys but they are not polys, polys are organized points in space, and they tesselate into a finite number of triagles cause they exist from a finite number of points.

Nurbs are tesselated to a finite number of triangles BUT with a resolution defined by the user/software, and in reality they are the graphed solutions of equations, so they have infinite solutions/points, that get interpolated by the sofware to produce a result of finite points (simply put, no jaggies or hard edges no matter how close you look ). There are equations for defining and controling sets of curves to turn them into surfaces, and that is the visual result.

Look up nurbs in wikipedia if you want the complete definitions and math.

I don't have a math or a programming degree, I'm a chemist and my math is not too high level (only had two advanced math courses ) and I apologize to anyone if what I'm writting here is bogus.

[joojaa]

QUOTE
So, although everything gets converted to polygons at the display/render stage, NURBS tessellation is totally adaptive. Mesh tessellation is only adaptive inasmuch as Maya automagically divides n-sided polygons into triangles

Thats a debatable issue, for example saying that nurbs always get converted to polygons for render. One get the feeling thet the renderer's do this unintelligently. Thye dont necceserily do it up fornt,

For example both mr and prman tessellate the nurbs on fly, renderman specially chunks it up to smeller nurbs pieces thet then get polygonized locally per sample basis. So it in fact results in surface that is actually smooth no matter what. Even mr has a scheme like this for nurbs but prman handles subds the same way.

In fact prman does it so effectively that it even handles polygons tha same way, this means that the renderer itself is WAY less efficient on poly surfaces that not only do worse renders out of them, but also use more memory and less quality. So sending renderer's like this readily quantized polygon meshes is just a a waste of time.

Second many renderer's indeed do not triangulate quads, prman included.

So while its superficially true, its farmore intelligently done for any need to traingualte things up fornt, and indeed it does only make rendering slower.