# TIN Model: Components (Nodes, Edges, Triangles, & Hull) & Advantages (Especially for GATE-Geospatial 2022)

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## TIN Model

A triangular irregular network (TIN) is a digital data structure used in a geographic information system (GIS) for the representation of a surface. TIN is an irregular Network stored GIS data for 3D surface model. A TIN is a vector-based representation of the physical land surface or sea bottom.

The basic unit of TIN Model is a triangle. The TIN model represents a surface as a set of contiguous, non-overlapping triangles. The triangle is represented by a sequence of three nodes.

The TIN model is attractive because of its simplicity and economy and is a significant alternative to the regular raster of the GRID model.

### Advantages and Disadvantages of TIN Model

Advantages – Ability to describe the surface at different level of resolution Efficiency in strong data

Disadvantages – in many cases require visual inspection and manual control of the network

## Components of TIN

Four components of TIN describe below:

### Nodes

The nodes originate from the points and line vertices contained in the input data sources. Every node is incorporated in the TIN triangulation.

### Edges

Every node is joined with its nearest neighbors by edges to form triangles which satisfy the **Delaunay** criterion. Each edge has two nodes, but a node may have two or more edges.

### Triangles

Each triangular facet describes the behavior of a portion of the TIN՚s surface. The x, y, z coordinate values of a triangle՚s three nodes can be used to derive information about the facet, such as slope, aspect, surface area, and surface length.

### Hull

The hull of a TIN is formed by one or more polygons containing the entire set of data points used to construct the TIN. The hull polygons define the zone of interpolation of the TIN. The hull of a TIN can be formed by one or more polygons which can be non-convex.