TIN - Triangular Irregular Network
By Arcinfo
The TIN data structure is based on two basic elements:
points with x,y,z values, and a series of edges
joining these points to form triangles.
This triangular mosaic forms a continuous faceted surface,
much like a jewel.
TIN's triangulation method satisfies the Delaunay criterion.
Format
TIN /* File type identifier */
BEGT /* Beginning of TIN group */
TNAM name /* Name of TIN */
MAT id /* TIN material id */
VERT nv /* Beg. of vertices */
x1 y1 z1 lf1 /* Vertex coords. */
x2 y2 z2 lf2
.
.
.
xnv ynv znv lfnv
TRI nt /* Beg. of triangles */
v11 v12 v13 /* Triangle vertices */
v21 v22 v23
.
.
.
vnt1 vnt2 vnt3
ENDT /* End of TIN group */
/* Repeat TIN group for other TINs */
Cards
|
Card Type |
TIN |
|
Description |
File type identifier. Must be on first line
of file. No fields. |
|
Required |
YES |
|
Card Type |
BEGT |
|
Description |
Marks the beginning of a group of cards describing
a TIN. There should be a corresponding ENDT card at a latter point in
the file. No fields. |
|
Required |
YES |
|
Card Type |
TNAM |
|
Description |
Provides a name to be associated with the
TIN. |
|
Required |
NO |
|
Format |
TNAM name |
|
Sample |
TNAM bathymetry |
|
Field |
Variable |
Value |
Description |
|
1 |
name |
str |
The name of the TIN. |
|
Card Type |
MAT |
|
Description |
Associates a material id with the TIN. This
is typically the id of the material which is below the TIN. |
|
Required |
NO |
|
Format |
MAT id |
|
Sample |
MAT 3 |
|
Field |
Variable |
Value |
Description |
|
1 |
id |
+ |
The material ID. |
|
Card Type |
VERT |
|
Description |
Lists the vertices in the TIN |
|
Required |
YES |
|
Format |
VERT nv
x1
y1
z1
lf1
x2
y2
z2
lf2
.
.
xnv
ynv
znv
lfnv |
|
Sample |
VERT 4
0.0 3.1 7.8 0
5.3 8.7 4.0 1
2.4 4.4 9.0 1
3.9 1.2 3.6 0 |
|
Field |
Variable |
Value |
Description |
|
1 |
nv |
+ |
The number of vertices in the TIN. |
|
2-4 |
x,y,z |
± |
Coordinates of vertex. |
|
5 |
lf |
0,1 |
Locked / unlocked flag for vertex (optional).
0=unlocked, 1=locked. Repeat fields 2-5 nv times. |
|
Card Type |
TRI |
|
Description |
Lists the triangles in the TIN |
|
Required |
NO |
|
Format |
TRI nt
V11
v12
v13
v21
v23
v23
.
.
vnt1
vnt2
vnt3 |
|
Sample |
TRI 4
5 1 4
4 1 2
4 2 3
5 4 3 |
|
Field |
Variable |
Value |
Description |
|
1 |
nt |
+ |
The number of triangles in the TIN. |
|
2-4 |
v1,v2,v3 |
+ |
Vertices of triangle listed in a counter-clockwise
order. Repeat nt times. |
|
Card Type |
ENDT |
|
Description |
Marks the end of a group of cards describing
a TIN. There should be a corresponding BEGT card at a previous point in
the file. No fields. |
|
Required |
YES |
|