.ply - Plyhedral file format


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The .ply file format is a simple object description that was designed as a convenient format for researchers who work with polygonal models. Early versions of this file format were used at Stanford University and at UNC Chapel Hill.

A description as well as examples, codes of the PLY file format can be found at this link.

Below is the complete ASCII description for a cube. The header of a binary version of the same object would differ only in substituting the word "binary_little_endian" or "binary_big_endian" for the word "ascii". The comments in brackets are NOT part of the file, they are annotations to this example. Comments in files are ordinary keyword-identified lines that begin with the word "comment".

ply
format ascii 1.0           { ascii/binary, format version number }
comment made by Greg Turk  { comments keyword specified, like all lines }
comment this file is a cube
element vertex 8           { define "vertex" element, 8 of them in file }
property float x           { vertex contains float "x" coordinate }
property float y           { y coordinate is also a vertex property }
property float z           { z coordinate, too }
element face 6             { there are 6 "face" elements in the file }
property list uchar int vertex_index { "vertex_indices" is a list of ints }
end_header                 { delimits the end of the header }
0 0 0                      { start of vertex list }
0 0 1
0 1 1
0 1 0
1 0 0
1 0 1
1 1 1
1 1 0
4 0 1 2 3                  { start of face list }
4 7 6 5 4
4 0 4 5 1
4 1 5 6 2
4 2 6 7 3
4 3 7 4 0

This example demonstrates the basic components of the header. Each part of the header is a carriage-return terminated ASCII string that begins with a keyword. Even the start and end of the header ("ply" and "end_header") are in this form. The characters "ply" must be the first four characters of the file, since they serve as the file's magic number.

Some free 3D models described in PLY file format can be found at here (many thanks Edward Verbree at TU Delft for this link).
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