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

±

Coordsinates 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