Mathematica Import/Export Format

NOFF (.noff, .cnoff)

NOFF 3D geometry format.
Used for storing and exchanging 3D models.
NOFF is an acronym derived from Object File Format.
Related to OFF and COFF.
Occasionally called CNOFF if color information is present.
ASCII or binary format.
Represents a single 2D or 3D object.
Stores a collection of planar polygons with possibly shared vertices and vertex normal data.

Import and Export support ASCII and binary versions of the NOFF file format.

Mathematica reads and writes vertex colors or face colors.

If both vertex and face colors are present in the file, Import returns the vertex color information.

IMPORT AND EXPORT

Import["file.off"]imports a NOFF file as graphics.

Export["file.off", expr] exports graphics to a binary NOFF file.

For NOFF files representing a 3D object, Import["file.off"] returns an expression of the form Graphics3D[ GraphicsComplex[vertices, primitives, opts]].

Planar objects are imported as Graphics[ GraphicsComplex[vertices, primitives, opts].

Import["file.off", elem] imports the specified element from a NOFF file.

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

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

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

Export["file.off", expr, elem] creates a binary NOFF file by treating expr as specifying element elem.

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

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

Export["file.off", {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 NOFF 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

Data representation elements:

	"Graphics"	2D NOFF file represented as a Graphics object
	"Graphics3D"	3D geometry represented as a Graphics3D object
	"GraphicsComplex"	NOFF file as a GraphicsComplex object
	"PolygonColors"	face color information, given as a list of color primitives associated with each polygon
	"PolygonData"	the polygon elements in indexed form
	"PolygonObjects"	list of Polygon primitives given in absolute coordinates
	"VertexColors"	colors associated with each vertex, given as a list of color primitives
	"VertexData"	list of vertex coordinates
	"VertexNormals"	normal vectors corresponding to the vertices given by "VertexData"

Import and Export by default use the "Graphics3D" element to represent 3D geometries, and the "Graphics" element for 2D objects.

The "VertexData" element corresponds to the first argument of GraphicsComplex.

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 NOFF.

Detailed property:

"BinaryFormat"

True

whether the file is in ASCII or binary format

Binary NOFF files store information as "Integer32" and "Real32" data types, always using the setting "ByteOrdering"->1.

Advanced options:

	"InvertNormals"	False	whether to invert the orientation of vertex normals
	"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 NOFF 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 NOFF, and the inverse transformation when exporting to NOFF.