Polygon File Format

Revision as of 17:48, 15 February 2010

Title(s): PLY - Polygon File Format or Stanford Triangle Format

Version ID: 1.0 - Currently used version

Date released: 1994

Date: 1994

Creator(s): Stanford University

Contributor(s): Stanford University

Relationships:

• Previous Version(s): NONE

• Contains: NONE

• Syntax Format(s): NONE

• Family Format(s): NONE

Example(s):

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

• Sample ascii ply file [[1]]
• ply.h [[2]]
• plytest.c [[3]]
• plyfile.c [[4]]
• plydocs.txt [[5]]

Identifier: - A URL or other identifier that refers to the engineering format.

Documentation:

• Structure of a typical PLY file
  • Header
  • Vertex List
  • Face List
  • lists of other elements)
• Scalar data types

name        type        number of bytes
---------------------------------------
char       character                 1
uchar      unsigned character        1
short      short integer             2
ushort     unsigned short integer    2
int        integer                   4
uint       unsigned integer          4
float      single-precision float    4
double     double-precision float    8

Identifier: The Stanford 3D Scanning Repository [[6]]

File Extensions: .PLY

Applications: - Applications that the engineering format uses.

Magic numbers: ply - Typically starts with "ply" as the header followed by either "format ascii 1.0", "format binary_little_endian 1.0", or "format binary_big_endian 1.0" as the next line.

Format(s): application/octet-stream

Sustainability Factors: - Facts about the sustainability of this particular engineering format.

• Standardization: - Information regarding standardization attempts with this format.

• Adoption: - Information about how this format has been adopted by other organizations.

• • Licensing and patent claims: - Any licenses or patent claims that the engineering format makes.

• Self-documentation: - Any self-documentation capabilities of the format.

• External dependencies: - Anything that the format depends on outside of its control to function.

• Technical protection considerations: - Any considerations that are necessary when it comes to technical protection.

Typical use:CAD/CAM

File classification: - Specific properties that pertain to this engineering format.

• Type {Binary, Text}: Both
• Raster data: - Section describes whether or not the engineering format supports raster data.
  • Raster data 2D: - Can the format support 2D raster data? Example: A format that can contain 2D pixelated data supports 2D raster data.
    • Is Supported: - Is the feature supported in the engineering format?
    • Description: - This field is used to describe the support or lack of support of the feature.
  • Raster data 3D: - Can the format support 3D raster data? Example: A format that can contain 2D pixelated data of a 3D model supports 3D raster data.
    • Is Supported: - Is the feature supported in the engineering format?
    • Description: - This field is used to describe the support or lack of support of the feature.
• Geometric representation: - Section describes whether or not the engineering format supports geometric representations.
  • Implicit representation: - Section describes whether or not the engineering format supports implicit representations.
    • Implicit surfaces: - Can the format support implicit surfaces? Example: A format that can contain surfaces that are generated with mathematical equations that contain the independent variables x, y, and z, like x^2 + y^2 + z^2 * R^2 = 0, supports implicit surfaces.
      • Is Supported: - Is the feature supported in the engineering format?
      • Description: - This field is used to describe the support or lack of support of the feature.
    • Implicit curves: - Can the format support implicit curves? Example: A format that can contain curves that are generated with mathematical equations that contain the independent variables x, y, and z, supports implicit curves.
      • Is Supported: - Is the feature supported in the engineering format?
      • Description: - This field is used to describe the support or lack of support of the feature.
    • Point set: - Can the format support point sets? Example: A format that supports surfaces and lines that are generated by points that form triangles supports point sets.
      • Is Supported: - Is the feature supported in the engineering format?
      • Description: - This field is used to describe the support or lack of support of the feature.
  • Mesh: - Section describes whether or not the engineering format supports mesh.
    • Manifold surface meshes: - Can the format support manifold surface meshes? Example: A format that supports surfaces that are mathematical spaces in which every point has a neighborhood which resembles Euclidean space
      • Is Supported: - Is the feature supported in the engineering format?
      • Description: - This field is used to describe the support or lack of support of the feature.
    • Manifold volume meshes: - Can the format support manifold volume meshes? Example: A format that supports volumes that are mathematical spaces in which every point has a neighborhood which resembles Euclidean space
      • Is Supported: - Is the feature supported in the engineering format?
      • Description: - This field is used to describe the support or lack of support of the feature.
    • Non-manifold meshes: - Can the format support non-manifold meshes? Example: A format that supports meshes that are not manifolds
      • Is Supported: - Is the feature supported in the engineering format?
      • Description: - This field is used to describe the support or lack of support of the feature.
  • Parametric representation: - Section describes whether or not the engineering format supports parametric representations.
    • Parametric surfaces: - Can the format support parametric surfaces? Example: A format that can contain surfaces that are generated with parametric equations supports parametric surfaces.
      • Is Supported: - Is the feature supported in the engineering format?
      • Description: - This field is used to describe the support or lack of support of the feature.
    • Parametric curves: - Can the format support parametric curves? Example: A format that can contain curves that are generated with parametric equations supports parametric curves.
      • Is Supported: - Is the feature supported in the engineering format?
      • Description: - This field is used to describe the support or lack of support of the feature.
  • Contour sets: - Can the format support contour sets?
    • Is Supported: - Is the feature supported in the engineering format?
    • Description: - This field is used to describe the support or lack of support of the feature.
  • NURBS: - Can the format support Non Uniform Rational Basis Splines? Examples: The engineering formats IGES, STEP, ACIS, and PHIGS
    • Is Supported: - Is the feature supported in the engineering format?
    • Description: - This field is used to describe the support or lack of support of the feature.
• Multi-resolution models: - Can the format support models with multiple resolutions? Examples: A format that supports a highly detailed and lowly detailed model simultaneously supports multi-resolution models.
  • Is Supported: - Is the feature supported in the engineering format?
  • Description: - This field is used to describe the support or lack of support of the feature.
• Dynamics: - Section describes whether or not the engineering format supports dynamics.
  • Kinematics: - Can the format support kinematics? Example: Does the format allow model parts to rotate?
    • Is Supported: - Is the feature supported in the engineering format?
    • Description: - This field is used to describe the support or lack of support of the feature.
  • Assembly: - Can the format support assembly? Example: Does the format allow the assembly instructions to be explicitly specified with a model?
    • Is Supported: - Is the feature supported in the engineering format?
    • Description: - This field is used to describe the support or lack of support of the feature.
  • Force(s): - Can the format support forces? Example: Does the format support acceleration forces?
    • Is Supported: - Is the feature supported in the engineering format?
    • Description: - This field is used to describe the support or lack of support of the feature.
• Boundary representation - Can the format support models with boundary representations?
  • Manifold surface boundary representations: - Can the format support manifold surface boundary representations? Example: The engineering format STEP
    • Is Supported: - Is the feature supported in the engineering format?
    • Description: - This field is used to describe the support or lack of support of the feature.
  • Manifold volume boundary representations: - Can the format support manifold volume boundary representations? Example: The engineering format STEP
    • Is Supported: - Is the feature supported in the engineering format?
    • Description: - This field is used to describe the support or lack of support of the feature.
  • Non-manifold boundary representations: - Can the format support non-manifold boundary representations? Example: The engineering format STEP
    • Is Supported: - Is the feature supported in the engineering format?
    • Description: - This field is used to describe the support or lack of support of the feature.
• Material transparency: - Can the format support transparency? Example: Does the format allow models to have a clear window in a car?
  • Is Supported: - Is the feature supported in the engineering format?
  • Description: - This field is used to describe the support or lack of support of the feature.

References: Paul Bourke, "The University of Western Australia", ["http://local.wasp.uwa.edu.au/~pbourke/dataformats/ply/", December 2010]