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File Formats - Wireframe
Description
Wireframe (.wfr) files are used to represent tessellated surfaces. The
surfaces consist of vertices, patches (triangles), and, optionally edges.
In general, the file consists of a prolog, a header, a sequence of
vertices, followed by a sequence of triangles, followed by a sequence of
edges, but the detailed structure depends on the minor rev. Minor rev = 1,
2, 4 are similar, and a documented together. Minor rev =3 is documented
last.
Minor Rev
EMSE v4.2 and above write minor rev 3 and 4,
but can read earlier revisions.
Minor rev = 4
Indices rather than address are used to link objects such as triangles and
their associated vertices.
Minor rev = 3
The connectivity information in minor rev=3 files is stripped (i.e. only
essential vertex and triangle information is stored). Connectivity
information must be reconstructed once the file is read. The header
consists of only one field (the type field).
Minor rev = 2
Explicit address pointers are stored. The header includes the type field,
but the file is otherwise identical to minor rev=1.
Minor rev = 1
Explicit address pointers are stored. The header omits the type field.
Comments
Wireframe files must not have comment lines.
Header
The header consists of up to 5 entries in mandatory sequence (minor rev
1, 2, 4), shown in Table A-1.
|
Name |
Format |
Description |
|
radius |
%f |
Sphere radius used for initial create step |
|
#vertex |
%d |
Number of vertices in this file |
|
#patch |
%d |
Number of triangles in this file |
|
#edge |
%d |
Number of edges in this file |
|
type |
|
Type must be one of the following |
|
|
|
| m-rev=2 |
m-rev=3,4 |
Type |
| 0 |
0x00000000 |
Unknown |
|
64 |
0x00000040 |
Scalp, head frame |
|
|
0x00080040 |
Scalp, voxel frame |
|
|
0x00100040 |
Scalp, MRI frame |
|
128 |
0x00000080 |
Outer skull, head frame |
|
|
0x00080080 |
Outer skull, voxel frame |
|
|
0x00100080 |
Outer skull, MRI frame |
|
256 |
0x00000100 |
Inner skull, head frame |
|
|
0x00080100 |
Inner skull, voxel frame |
|
|
0x00100100 |
Inner skull, MRI frame |
|
512 |
0x00000200 |
Cortex, head frame |
|
|
0x00080200 |
Cortex, voxel frame |
|
|
0x00100200 |
Cortex, MRI frame |
|
Table A-1
Note: It is
an undefined situation (and may produce an error) if both the voxel and
MRI frame bits are set.
Vertex field
Table A-2 defines the vertex fields (minor rev = 1, 2, 4)
|
Name |
Format |
Description |
|
|
%d %x %d |
index, address, channel index |
|
Location |
3 %g %g %g |
replace %g %g %g with the point location (meters) |
|
Outward normal |
3 %g %g %g |
replace %g %g %g with outward normal |
|
Potential |
%g |
current or voltage |
|
Curvature |
%g |
curvature |
Table A-2
Patch field
Table A-3 defines the patch fields (minor rev = 1, 2, 4)
|
Name |
Format |
Description |
|
|
%d %x |
index, address |
|
|
%g %g %g %g |
Solid angle, magnitude, potential, area |
|
Location |
%g %g %g |
replace %g %g %g with the center location (meters) |
|
Outward normal |
%g %g %g |
replace %g %g %g with outward normal |
|
Vertices |
%x
%x %x |
Vertex addresses (m-rev 1,2) or indices (m-rev4) |
|
Edges |
%x %x %x |
edge addresses (m-rev 1,2) or indices (m-rev4) |
Table A-3
Edge fields
Table A-4 defines the edge fields (minor rev = 1, 2, 4)
|
Name |
Format |
Description |
|
Index |
%d %x |
index, address |
|
|
%x %x |
Vertex address (m-rev= ,2) or index (m-rev=4) |
Table A-4
Example 1
The following example illustrates a tetrahedron saved in
minor rev = 2 format. The tetrahedron is shown in Figure F-1.
3 4000
2
0 4 4 6 64
0 0x01f87620 -1 3 0 0 0
3 0 0 0
0 0
1 0x01f94244 -1 3 0.5 0.867 0
3 0 0 0
0 0
2 0x01f94380 -1 3 1 0 0
3 0 0 0
0 0
3 0x01f93ec8 -1 3 0.5 0.289 0.816
3 0 0 0
0 0
0 0x01f93b90 0 0 0 0.4335
0.5 0.289 0
0 0 -1
0x01f87620 0x01f94244 0x01f94380 0x01f93fb0 0x01f93ffc 0x01f94048
1 0x01f93c68 0 0 0 0.433157
0.333333 0.385333 0.272
-0.816645 0.47096 0.333597
0x01f87620 0x01f93ec8 0x01f94244 0x01f94094 0x01f940e0 0x01f93fb0
2 0x01f93d40 0 0 0 0.432833
0.5 0.0963333 0.272
0 -0.942627 0.333847
0x01f87620 0x01f94380 0x01f93ec8 0x01f94048 0x01f9412c 0x01f94094
3 0x01f93858 0 0 0 0.433157
0.666667 0.385333 0.272
0.816645 0.47096 0.333597
0x01f94244 0x01f93ec8 0x01f94380 0x01f93ffc 0x01f940e0 0x01f9412c
0 0x01f93fb0 0x01f87620 0x01f94244
1 0x01f93ffc 0x01f94244 0x01f94380
2 0x01f94048 0x01f94380 0x01f87620
3 0x01f94094 0x01f87620 0x01f93ec8
4 0x01f940e0 0x01f94244 0x01f93ec8
5 0x01f9412c 0x01f94380 0x01f93ec8
Figure F-1
Example 2
The following example illustrates a tetrahedron saved in minor rev = 4
format.
3 4000
4
0 4 4 6 40
-1 3 0 0 0
3 0 0 0
0 0
-1 3 0.5 0.867 0
3 0 0 0
0 0
-1 3 1 0 0
3 0 0 0
0 0
-1 3 0.5 0.289 0.816
3 0 0 0
0 0
0 0 0 0.4335
0.5 0.289 0
0 0 -1
0 1 2 0 1 2
0 0 0 0.433157
0.333333 0.385333 0.272
-0.816645 0.47096 0.333597
0 3 1 3 4 0
0 0 0 0.432833
0.5 0.0963333 0.272
0 -0.942627 0.333847
0 2 3 2 5 3
0 0 0 0.433157
0.666667 0.385333 0.272
0.816645 0.47096 0.333597
1 3 2 1 4 5
0 1
1 2
2 0
0 3
1 3
2 3
Minor rev = 3
The connectivity information in minor rev=3 files is stripped (i.e.
essential vertex and triangle information is stored). Connectivity
information must be reconstructed once the file is read. The header
consists of only one field (the type field, see Table A-1). Each
subsequent line represents either a vertex or a triangle.
|
Name |
Format |
Description |
|
vertex |
v %f %f %f |
A vertex is represented by the character 'v' followed by the (xyz)
coordinates |
|
triangle |
t %f %f %f |
A triangle is represented by the character 't' followed by the indices
of the 3 vertices. The vertex index is given by its sequence within
the file. |
Example 3
The following example illustrates a tetrahedron saved in minor rev = 3
format.
3 4000
3
40
v 0 0 0
v 0.5 0.867 0
v 1 0 0
v 0.5 0.289 0.816
t 0 1 2
t 0 3 1
t 0 2 3
t 1 3 2
Figure F-2
Tetrahedron used in examples 1-3, showing vertices v0-v3 with their (xyz)
locations, and triangles t0-t3.
Figure F-2
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