Mathematica Import/Export Format

BYU (.byu)

3D geometry format.
Used for visualization of 3D polygonal meshes in CAD systems and other applications.
BYU is an acronym for Brigham Young University.
ASCII format.
Represents 3D objects as collections of polygon primitives.
Can store multiple 3D objects.

Import and Export fully support the BYU format.

IMPORT AND EXPORT

Import["file.byu"] imports a BYU file as a Graphics3D object.

Export["file.byu", expr] exports a Graphics3D expression to a BYU file.

Import["file.byu"] returns an expression of the form Graphics3D[ GraphicsComplex[vertices, primitives, opts]].

Import["file.byu", elem] imports the specified element from a BYU file.

Import["file.byu", {elem, sub_a, sub_b, ...}] imports a subelement.

Import["file.byu", {{elem₁, elem₂, ...}}] imports multiple elements.

The import format can be specified with Import["file", "BYU"] or Import["file", {"BYU", elem, ...}].

Export["file.byu", expr, elem] creates a BYU file by treating expr as specifying element elem.

Export["file.byu", {expr₁, expr₂, ...}, {{elem₁, elem₂, ...}}] treats each expr_i as specifying the corresponding elem_i.

Export["file.byu", expr, opt₁->val₁, ...] exports expr with the specified option elements taken to have the specified values.

Export["file.byu", {elem₁->expr₁, elem₂->expr₂, ...}, "Rules"] uses rules to specify the elements to be exported.

See the reference pages for full general information on Import and Export.

ImportString and ExportString support the BYU format.

ELEMENTS

General Import elements:

	"Elements"	list of elements and options available in this file
	"Rules"	full list of rules for each element and option
	"Options"	list of rules for options, properties, and settings

Graphics elements:

	"Graphics3D"	BYU file represented as a Graphics3D object
	"GraphicsComplex"	list of GraphicsComplex objects, each representing a 3D geometry stored in the file

Import and Export use the "Graphics3D" element by default for BYU files.

Data representation elements:

	"PolygonData"	the polygon data in indexed form
	"PolygonObjects"	list of Polygon primitives given in absolute coordinates
	"VertexData"	list of vertex coordinates

Import with a data representation element returns a list whose elements correspond to the geometry objects stored in the file.

Import["file.byu", {"PolygonData", n}] gives the polygon data of the n geometry object.

OPTIONS

General Import options:

Background	Automatic	what background color to use
ImageSize	Automatic	overall size of the graphics to display
Lighting	Automatic	what simulated lighting to use in coloring 3D surfaces

All options of Graphics3D can be given when importing from BYU.

Advanced option:

"VerticalAxis"

{0,0,1}

orientation to assume for the coordinate system used in the file

By default, Mathematica assumes that in the coordinate system used by the BYU format the vertical axis corresponds to the third coordinate.

With the setting "VerticalAxis"->{0, 1, 0}, Mathematica will apply the transformation {x, y, z}->{x, -z, y} to all graphics coordinates when importing from BYU, and the inverse transformation when exporting to BYU.