[MOAB-dev] Geodesic mesh representation

[Iulian Grindeanu]

you maybe can follow this example: 

https://bitbucket.org/fathomteam/moab/src/bee2e77e416976393a63a221a814d85285403a7e/examples/old/FileRead.cpp?at=master 

It is a 2d mesh, but it reads from 2 files, one with coordinates position and one with connectivity for triangles. 

You can create a mesh with just create_vertex() and create_element() methods on moab::Interface 

----- Original Message -----

| I have the mesh in a flat text file format- one file with vertex
| coordinates, one file that lists the connectivity of faces to
| vertices
| (ie for each face, what are the vertices that "bound" it).

| Topologically, the mesh is 2D since the highest dimensionality
| element
| is a face (bounded by edges). However, the mesh represents a
| discretization of the surface of a sphere, so vertex coordinates are
| 3D (x,y,z). Since I am on the surface of a sphere of unit radius, I
| could always go to a 2D coordinate representation in terms of angles
| and just store the 3D coordinates as Tag values. Then everything
| would
| be 2D (although the coordinates would be weird).

| It is unclear to me how to define a 3D mesh from this, since there
| really are no cells (elements of dimension = 3) in the mesh.

| On Wed, Nov 6, 2013 at 4:44 PM, Iulian Grindeanu <iulian at mcs.anl.gov>
| wrote:
| >
| >
| > ________________________________
| >
| > Dear Moab-Dev,
| >
| > I have a geodesic mesh (like MPAS or GCRM) and I was wondering what
| > the best way to represent the mesh in MOAB was. It is topologically
| > 2D
| > but it is embedded in a 3D manifold (so vertex coordinates are
| > x,y,z).
| > I was thinking that I would treat the mesh as 2D, feed in "bogus"
| > vertex coordinates and just use tags over the mesh elements to keep
| > track of the actual mesh coordinates. This way, I keep the 2D
| > topological structure (which is more important for my application
| > anyways). Is this a good approach?
| >
| > Thanks,
| > Chris Eldred
| >
| > --
| > Chris Eldred
| > DOE Computational Science Graduate Fellow
| > Graduate Student, Atmospheric Science, Colorado State University
| > B.S. Applied Computational Physics, Carnegie Mellon University,
| > 2009
| > chris.eldred at gmail.com / celdred at atmos.colostate.edu
| >
| > Probably I don't understand what you need :(
| >
| > What kind of format do you have ? netcdf? Is the mesh on a sphere /
| > surface?
| >
| > The vertex coordinates are retrieved with "get_coords" methods, and
| > set with
| > set_coords methods, or use "coords_iterate" type methods in
| > readUtil
| > interface.
| >
| > Why not keep the full 3d mesh? what is so special about the 2d
| > topological
| > structure?
| > Is it structured in any way? Can you use the MPAS reader or not?
| >
| > Iulian
| >

| --
| Chris Eldred
| DOE Computational Science Graduate Fellow
| Graduate Student, Atmospheric Science, Colorado State University
| B.S. Applied Computational Physics, Carnegie Mellon University, 2009
| chris.eldred at gmail.com / celdred at atmos.colostate.edu
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