# What is Triangulated Irregular Network (TIN)? Triangulated Irregular Network Applications

## What is a Triangulated Irregular Network (TIN)?

A Triangulated Irregular Network (TIN) is a representation of a continuous surface made completely of triangular facets (a triangle mesh), which is mostly utilized in primary elevation modeling as the Discrete Global Grid.

The vertices of these triangles are formed from field recorded spot elevations using a number of approaches such as traditional surveying, Global Positioning System Real-Time Kinematic (GPS RTK), photogrammetry, or some other method.

TINs are helpful for the description and study of general horizontal (x and y) distributions and relationships since they are associated with three-dimensional data (x, y, and z) and topography.

A TIN is made up of a triangular network of vertices known as mass points that have corresponding coordinates in three dimensions and are linked by edges to form a triangular tessellation.

By showing the triangular facets, three-dimensional visualizations are easily constructed.

Points may be widely separated in locations with minimal fluctuation in surface height, but point density is enhanced in areas with more intensive variation in height.

## Background of Triangulated Irregular Network

TINs were originally created to improve spatial understanding of the Earth. Now, they are used in any application where there is a need to understand the relationship between a surface and its location.

There are many techniques that can be used to create a TIN including traditional surveying techniques and other direct geospatial survey techniques such as photogrammetric or GPS-based methods.

## TIN generation

A TIN can be generated in three main ways:

The first method uses topographical survey data from digital elevation model (DEM) datasets:

This form of TIN is the most conventional and is used in most applications. It has been created in various ways over the years, with different tradeoffs for the computational complexity of the generation.

There are different approaches that can be taken:

• “Distance based”: Vertices are placed to fit the area of interest using an approximate straight-line distance between them.
• “Point based”: Vertices are placed at important random spots.
• “Slope-based”: Vertices are placed on top of the maxima and minima of the terrain in order to preserve a smooth and natural look.

The second approach is called “Direct generation” or “traces”.

These methods, which don’t rely on any elevation model data, are generally slower than those using DEMs, although they do not require any preprocessing. They are in use for various applications including high-resolution digital elevation models and other digital terrain models.

The third method is called the “Discrete Global Grid” (DGG) approach, developed at the University of Utah.

It generates a Triangulated Irregular Network (TIN) from a point cloud, which requires very little preprocessing. It is also more accurate and faster than other production approaches because it does not rely on DEMs with map-like accuracy.

## Applications of Triangulated Irregular Network

The applications are discussed below.

### Application of Triangulated Irregular Network in Cartography (or map-making):

The primary application of TINs is in Cartography.

TINs are used to display topographic maps by showing the shape of the terrain.

They also help with understanding the surface characteristics and spatial relationships of geographic areas using shallow depth of field techniques such as shading and false coloring.

### Application of Triangulated Irregular Network in GIS:

TINs are one of the most commonly used geospatial data formats in geographic information systems (GIS).

The DGG format was created for TINs, which have a number of advantages over other formats:

• Note that not all data sets can be represented in TIN format.
• Some of the drawbacks of this method are its computational efficiency and accuracy.
• Due to the low density of mass points, they suffer from poor detail preservation in areas with large spot-to-spot differences between them.
• TINs also require extensive preprocessing before they can be interpreted or used as coordinates within GIS systems.

### Application of Triangulated Irregular Network in landslides:

TINs are the most popular and most applied visualization for all types of landslides, even if different methods are used for more specific types. By using only, the terrain attribute, it is easy to construct a TIN by connecting mass points.

### Application of Triangulated Irregular Network in Mining and oil exploration:

TINs are also widely used during oil exploration as a better than standard DEM for identifying area’s influence on the possible location of geologic structures.

A TIN is a necessity in these applications since it is necessary to determine the relationship between minerals found and the surface characteristics of geographic areas. More specifically, the use of TINs aids in the location of gold and other precious metals, oil and other hydrocarbons, and coal deposits.

### Application of Triangulated Irregular Network in Biology:

The application of TINs has been widely used in ecology and other fields of science related to biology. In these applications, TINs are used as a tool for understanding spatial variation. This allows scientists to identify patterns between different features within the terrain that are analyzed.

### Application of Triangulated Irregular Network in conservation and restoration:

The use of TINs in conservation and restoration projects has been widely used because of its visual appeal as well as its ability to help reveal various environmental conditions.

It helps to show the influence of anthropogenic disturbances on natural areas, while also suggesting the locations where vegetation management may be helpful.

## TIN representation

“TIN representation” is a collection of quantified points in three dimensions (x, y, and z) that represent the location or position of points in a scene.

It allows depicting the entire spatial distribution of a set of points on one single image showing the shape and relief of the terrain.

Using this approach, it is possible to observe how a site varies over multiple scales including local, regional and global scales.

The disadvantages of this method are in the visual interpretation of the data: it does not include information about surface height and thus all frequencies are summed up.

TINs can be represented in these different ways:

The first approach is called “Node based”. It is based on the assumption that the points are all connected to other points by lines. Generally, this is not possible due to large variations in surface height, so this is not a good representation.

The second representation can be called “Point based”.

In this method, a point at each of the mass points is created as an individual entity. The disadvantage of this approach is that it does not include information about surface height and thus all frequencies are summed up.

The third method, called “Volume-based”, is the most complex one, since it represents the combination of all others. It allows to represent a TIN in three different levels of detail: an overview or coarse level, an intermediate level and finally a fine level showing greater detail.

## Advantages of Triangulated Irregular Network

The advantages are but not limited to:

1. A TIN is a translucent triangulated mesh, making it ideal for visualizing and quantifying data that has characteristics such as irregularity, high density, and/or small area.
2. It can be used to represent large areas (between 1 km and 100 km in size) without having to create high-resolution DEMs from smaller scale (1 m or less) elevation data.
3. The TIN provides a higher picture of the surface than the grid.
4. The TIN is a ‘connectivity’ representation, which makes it easier to see how surface objects are related to each other and the terrain.
5. It is possible to find and identify small landforms that can be missed in other representations, such as GPS data, digital aerial photography and grids.
6. It retains the ‘spatial memory’ of the original data even if they are not sampled at regular intervals or distributed uniformly (with no repeats).
7. The algorithm is simple and can be performed relatively easily by commonly used GIS software and computer programs.
8. It is widely accepted and widely used in the field of geography and cartography, being one of the most frequently applied techniques in them.
9. It is a powerful tool for making geospatial information available, since the output DEMs from digital terrain models (DTMs) can be viewed using a wide variety of easy-to-use viewers that cover all platforms (i.e., personal computers, tablets, smartphones and embedded devices).

## Disadvantages of Triangulated Irregular Network

The disadvantages are but are not limited to:

1. The TIN produces three-dimensional points that represent the position of the data source.
2. The TIN uses projection or elevation values and is sensitive to scale and angle, which makes it difficult to compare data with other data sets and maps.
3. When comparing two different representations of the same terrain, one must be careful not to confuse differences in scale, angle and application area.
4. The TIN does not provide information about surface height; therefore, all frequencies are summed up.
5. Individual mass points are not represented, leading to visual anomalies associated with those points.
6. The TIN is less accurate than other techniques, because data may originate from different sources or be displayed without proper correction (scale and elevation adjustment).
7. Images do not simulate the actual spatial variation of the terrain and therefore cannot also represent actual distributions of shapes and surfaces, as well as showing their relationships over space and time.
8. The TIN is not suitable for representing large areas or irregular surface features, such as islands, steep cliffs, and vegetation.
9. The TIN requires the use of a software that can process the data and generate a rendered image or three-dimensional model, which can be time-consuming.

## Triangulated Irregular Network (TIN) vs Digital Elevation Model (DEM)

A Digital Elevation Model (DEM) is a depiction of the Earth’s bare ground (bare earth) topographic surface that does not include trees, buildings, or other surface items. DEMs are made using a variety of methods. USGS DEMs were formerly obtained mostly from topographic maps.

The differences therefore are:

1. The TIN is less accurate than other techniques since it does not provide information about surface height (as DEMs do), therefore all frequencies are summed up.
2. While DEMs are easy to use and widely available, TINs require the use of a software that can process the data and generate a rendered image or three-dimensional model, which can be time consuming.
3. A DEM is generated from actual elevation values as opposed to TINs, which are based on arc length.
4. The TIN is a “connectivity” representation, which makes it easier to see how surface objects are related to each other and the terrain as well as it shows its relationships over space and time.
5. TINs generally have less detail than DEMs, since they are based on a very coarse grid.
6. The TIN is more general and can be applied to very large areas, which a DEM cannot depict.
7. The TIN can be better suited for representing data that has irregularity, high density and/or small area (e.g., location of many small buildings, high densities in urban areas, and surface irregularities) unlike DEMs
8. TINs are widely accepted for other applications than visualizing terrain.
9. A DEM is generated from actual elevation values as opposed to the TINs which are based on arc length (latitude and longitude).
10. A DEM represents the surface and not the surface objects, unlike terrain objects represented by TINs.
11. A DEM represents selected data (e.g., sampling points from a survey or a satellite image) as opposed to TIN which represents all available data points on earth’s surfaces.
12. The software can be used to generate a DEM from collected digital elevation points, while it is not easy to convert elevation values collected in other ways into TIN format.

## Triangulated Irregular Network FAQs

### What is the full form of TIN?

A TIN is a triangulated irregular network. A triangulated irregular network (TIN) is a three-dimensional surface created by connecting a series of points, lines, and polygons.

This surface is used to represent a real-world object, such as a geographical feature or a building. TINs can be created in a variety of software programs, including AutoCAD, Civil 3D, and ArcGIS.

A TIN is created by connecting the points that make up the surface with triangular facets. This creates a mesh of triangular faces that can be used to represent the surface in a 3-D space.

### How does TIN represent data?

Triangulated Irregular Network (TIN) represents data by each vertex (also known as “node”) representing the position of a particular sample. Thus, all other vertices (also known as “edges”) represent the distance between the two nodes.

### What are the advantages of TIN?

They include:

1. It can be used to represent large areas (between 1 km and 100 km in size) without having to create high-resolution DEMs from smaller scale (1 m or less) elevation data.
2. It uses projection or elevation values, which makes it more sensitive to scale, angle and accuracy. Therefore, it is easier to compare data with other data sets and maps. When comparing two different representations of the same terrain, one must be careful not to confuse differences in scale, angle and application area.
3. It is easy to use software steps to generate a TIN from collected digital elevation points.
4. It has a simple and intuitive functionality, which makes it easier for users to manage, edit and update the data. Therefore, it is easier for users to get an overall picture at initial stages of the project.
5. It maintains the spatial memory of the original data even if they are not sampled at regular intervals or distributed uniformly (with no repeats).

## What are the disadvantages of TIN?

They are but are not limited to:

1. It produces three-dimensional points that represent the position of the data source, which is not a physical surface but is connected or joined together by a network of lines.
2. When comparing two different representations of the same terrain, one must be careful not to confuse differences in scale, angle and application area.
3. The TIN is less accurate than other techniques as it does not provide information about surface height, therefore all frequencies are summed up.
4. Individual mass points are not represented, leading to visual anomalies associated with those points.
5. The TIN is not suitable for representing large areas or irregular surface features, such as islands, steep cliffs, and vegetation.
6. Images do not simulate the actual spatial variation of the terrain and therefore cannot also represent actual distributions of shapes and surfaces, as well as showing their relationships over space and time.
7. It is difficult to generate a TIN if there is irregularity/non-uniformity in the shape of data sources.

### What is triangular irregular network?

Triangulated Irregular Network (TIN) is a geospatial data structure to represent terrain information.

### What is the difference between Triangular Irregular Network and Digital Elevation Model?

Digital Elevation Model (DEM) is a type of TIN. The main difference between DEM and TIN is that the latter does not have the elevation values, but only the arcs that connect them.

DEMs are widely used in GIS for modelling three-dimensional landscapes and for representing surface topography.

### What is triangular irregular network used for?

Triangular irregular networks (TIN) have been utilized by the GIS community for many years as a digital way of representing surface morphology. TINs are a type of vector-based digital geographic data that are created by triangulating a set of vertices (points).

### Why do TINs exist?

TINs are a way to model and represent 3D features on the earth’s surface such as hillslopes, terrains, landscapes and relief with less data resolution than conventional digital surfaces.

### What is the difference between Triangular Irregular Network and Digital Surface Model?

Digital Surface Model (DSM) is a digital representation of ground surfaces that can be used in GIS. The DSM consists of a regular grid of triangular cells, where the vertices are connected by lines. The DSM is similar to TIN except that the points are evenly spaced, typically 250 meters apart.

### What is a 3D TIN?

A 3D TIN is a Triangular Irregular Network (TIN) that represents three-dimensional surfaces.

### What does TIN stand for in GIS?

A Triangulated Irregular Network (TIN) layer is a type of elevation surface that displays height values across a certain area. In ArcGIS Pro, TIN layers are available in both map and scene views.

### What kinds of data can you use to create TINs?

A TIN surface may be created using elevation-data-contained features such as points, lines, and polygons. Points can be used as elevation data spot locations.

Lines containing height information can be used to emphasize natural features such lakes, streams, mountains, and valleys.

### How are TINs created?

Tins are made up of points, polygons, and lines. The spots used to define the tin are known as mass points. Exclusion polygons are areas of continuous height, such as water surfaces. Finally, break lines are lines such as streams and shorelines.

### How are Triangulated Irregular Network TINs used?

TINs are widely used in GIS for representing surface morphology. They can also be used for the analysis and modeling of topography and terrain. TINs are often shown in 3D terrain mapping, together with maps and satellite images of physical objects such as roads, buildings, etc.

### What is an elevation contour line?

Elevation contour lines are curves that connect points of equal elevation on a map. Contour lines may be either below sea level or above sea level.

### Is TIN a raster or a vector?

The TIN structure is a vector-based topological data architecture for representing terrain data. The terrain surface is represented by TIN as a series of linked triangular facets.

TIN is a vector-based alternative to the classic raster representation of terrain surface – Digital Elevation Model (DEM).