Most multi-view reconstruction algorithms generate a triangle mesh, a set of points, or a set of voxels (cubes). We support these three types of output, but assume a standard format (Stanford's PLY format) to facilitate the evaluation process. In its ASCII form, PLY is a simple text format for meshes that is supported by the public domain Scanalyze program. Scanalyze is a geometry viewer and manipulator that runs on windows, linux, and irix.
Important: be sure and specify all points in the scene coordinate system defined by each data set (a sanity check is that your point coordinates should lie roughly within the bounding box specified in the README file).
One caveat is that, unlike meshes and voxels, we cannot evaluate photo-consistency of a true point cloud because visibility is not well-defined. For point clouds we will still evaluate geometric accuracy.
Please submit your results in one of the following three formats. Although there are public domain libraries to assist in the creation of PLY files, it is probably simplest to directly generate text files as described below.
Also, please let us know, for each data set, the run-time and machine specs that you used.
1. Mesh in PLY format (.ply)
The mesh file format specifies a list of floating point vertices (<x>, <y>, <z>) followed by a list of faces each specified by a list of vertex indices. Vertex indices start at 0 and are assumed to be listed in counter-clockwise order for each triangle so that the right-hand rule orients the implicit triangle normals in the front-facing direction.
RGB color is optional; if you do not wish to supply it, you can set the colors arbitrarily, or you can omit the "property uchar diffuse_*" lines as well as the (<r>, <g>, <b>) colors themselves.
--filestart--
ply
format ascii 1.0
element vertex <number of vertices>
property float x
property float y
property float z
property uchar diffuse_red
property uchar diffuse_green
property uchar diffuse_blue
element face <number of faces>
property list uchar int vertex_indices
end_header
<x> <y> <z> <r> <g> <b>
.
.
.
3 <index1> <index2> <index3>
.
.
.
--fileend--
Click here for more on PLY and a number of tools to convert to and from PLY and a number of other common mesh formats. Here's a sample mesh ply file. The mesh will be immediately viewable in Scanalyze. To see the stored color, turn on "Render/True color"; you can also turn on "Render/Emissive" to see the color as an emissive, rather than shaded, rendering.
2. List of Points in PLY format (.ply)
A list of points with floating point coordinates (<x>, <y>, <z>). RGB color is optional; if you do not wish to supply it, you can set the colors arbitrarily, or you can omit the "property uchar diffuse_*" lines as well as the (<r>, <g>, <b>) colors themselves.
--filestart--
ply
format ascii 1.0
element vertex <number of vertices>
property float x
property float y
property float z
property uchar diffuse_red
property uchar diffuse_green
property uchar diffuse_blue
end_header
<x> <y> <z> <r> <g> <b>
.
.
.
--fileend--
Here's a sample point ply file. To view this in Scanalyze, turn on "Render/Points" and "Render/Emissive". To see the stored color, turn on "Render/True color".
3. List of Voxels in PLY format (.ply)
A list of voxels (cubes) with floating point coordinates. <x> <y> <z> defines the center of the cube with diameter specified by <voxel diameter>. RGB color is optional; if you do not wish to supply it, you can set the colors arbitrarily, or you can omit the "property uchar diffuse_*" lines as well as the (<r>, <g>, <b>) colors themselves.
--filestart--
ply
format ascii 1.0
obj_info vox_diameter <voxel diameter>
element vertex <number of vertices>
property float x
property float y
property float z
property uchar diffuse_red
property uchar diffuse_green
property uchar diffuse_blue
end_header
<x> <y> <z> <r> <g> <b>
.
.
.
--fileend--
Here's a sample voxel ply file. To view this in Scanalyze, turn on "Render/Points" and "Render/Emissive". To see the stored color, turn on "Render/True color".
Last Changed September 23, 2005