Triangulated Irregular Network (TIN)

ROHIT KUMARGEO-INFORMATICSCUJ/I/2013/IGIO/26

DEFINATION

• TIN is a set of adjacent, non-overlapping triangles computed from irregularly spaced points, with x, y horizontal coordinates and z vertical elevations.

Advantages & Disadvantages

• Advantages– Can capture significant slope features (ridges, etc)– Efficient since require few triangles in flat areas.– Easy for certain analyses: slope, aspect, volume.

• Disadvantages– Analysis involving comparison with other layers difficult.

• TINs– are the most useful method for representing a continuous

surface in a vector GIS system.– data sets comprising any combination of contours,

breaklines and point elevations (either DEM or massed points) can be combined as input to create a TIN

• TINS are especially useful for analytical purposes • Good model for representing surfaces

• slope and aspect easily derived

• simplify the calculation of surface area and volume

TIN as a Storage Method

Tin Triangles in 3-D

(x3, y3, z3)

(x1, y1, z1) (x2, y2, z2)

x

y

z

Projection in (x,y) plane

Inputs for Creating a TIN

Mass Points Soft Breaklines Hard Breaklines

• Hard breaklines define locations of abrupt surface change (e.g. streams, ridges, road kerbs, building footprints, dams)• Soft breaklines are used to ensure that known z values along a linear feature are maintained in the tin.

A Portion of the TIN

Input Data for this Portion

Mass Points

Soft Breaklines

Hard Breaklines

TIN Vertices and Triangles

TIN Surface Model

WallerCreek

Street andBridge

3-D Scene

3-D Scene with Buildings

THE END

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