Within a modeling application such as Blender, objects are created
from insubstantial faces, each having its own defined boundaries,
but zero thickness. When artfully arranged and rendered, such
objects can rival photography for detail, clarity, and
believability. The possibilities are literally endless, and
endlessly impressive.
Blender holds a description of the physical details of objects in a
scene within a mesh block format. When it becomes desirable to
export a mesh object, Blender's export scripts perform the
operation. Such formats as .ply, obj, and .stl may differ in the
extent to which they can convey the nuances of a scene, but as far
as basic mesh characteristics are concerned, their purpose is merely
to describe the phyiscal attributes so that the analyzing functions
in another application can understand the geometry and depict it.
In the genre of file format converters, Blenbridge is a little
different from any other. It is meant to work solely with
non-manifold mesh. Mesh can be non-manifold in various ways, but the
defect of current interest is the presence of internal faces. By
co-locating the vertices of surface faces with those of internal
faces, an object can be constructed which carries the implication of
an assembly of solid blocks, such as the elements making up finite
element mesh. Such a ruse is only possible because Blender is
partially tolerant of non-manifold meshes of the necessary type. The
Blender .ply export script is also key, in that it writes manifold
and non-manifold mesh with equal disinterest.
Blenbridge has algorithms to interpret a certain type of
non-manifold .ply file as representing a finite element mesh, and
then to create it. And it can also translate finite element mesh
written in the .vtk format into .ply format, readable by Blender.
Thus it forms a bridge between the tenuous faces of 3D modeling
objects and the solidly defined volumetric elements of unstructured
grid mesh.