1POLYMERGE(1gv) POLYMERGE(1gv)
2
6 polymerge - merge coincident vertices, collinear edges, coplanar faces
7 in an OOGL OFF object
8
10 polymerge [-v vertex_thresh] [-e edge_thresh] [-f face_thresh] [-V]
11 [-E] [-F] [-d] [-b] [inputfile.off]
12
14 Polymerge eliminates redundancies from polyhedral objects in OOGL's OFF
15 format, and writes another OFF object to its standard output. (Option‐
16 ally it can produce instead an input file for Brakke's Evolver.)
17 Specifically, it combines nearly-coincident vertices, nearly-collinear
18 edges, and nearly-coplanar faces. Vertices which aren't used on any
19 face are deleted, as are faces with less than three vertices. Thresh‐
20 olds for approximate equality are adjustable from the command line.
21 Options are:
22 -v vertex_thresh
24 Merge vertices when they're closer than vertex_thresh apart; the
25 default is .00001.
26 -V Don't attempt to merge vertices.
28 -e edge_thresh
30 Merge edges where |sin(vertex_angle)| < edge_thresh; the default
31 is When edges are merged, the corresponding vertex is removed.
32 -E Don't attempt to merge edges. (4OFF edges are never merged.)
34 -f face_thresh
36 Merge faces sharing an edge where the faces are nearly coplanar:
37 when |sin(angle_between_face_normal_vectors)| < face_thresh.
38 The default is .03, or about two degrees. Note that merging can
39 create faces which are concave polygons.
40 -F Don't attempt to merge faces. (4OFF faces are never merged.)
42 -b Produce an output file in .fe format for Brakke's Surface
44 Evolver, instead of a new OFF file.
45 -d Include debugging information as comments in the new OFF object.
47 The comments indicate which vertices and faces in the original
48 object correspond to which in the new one. Messages include:
49 # Vtx nnn->mmm
51 Merged vertices nnn and mmm (both indices in the original
52 object).
53 # Merged face nnn into mmm (vertices vvv www) n1.n2 s
55 Faces nnn and mmm in the original object were merged; their com‐
56 mon edge joined original vertices vvv and www. The cosine of
57 the angle between the face normals was s.
58 vertex coordinates # newvertno [order] # oldvertno
60 Each vertex written appears with its new index, its order (num‐
61 ber of edges touching that vertex), and its old index (index of
62 a corresponding vertex in the original object).
63 face description # oldvertno ...
65 For each new face, with N vertices after reduction, the comment
66 indicates N corresponding vertices in the original object.
67
69 Stuart Levy, Geometry Center, University of Minnesota
70
72 anytooff(1), offconsol(1)
73
75 Coplanar faces are merged even if they were assigned different colors.
76 Should be able to handle binary OFF objects, but this hasn't been
77 tested.
78Geometry Center 25 July 1993 POLYMERGE(1gv)