How to Create a TIN from Point Data

Introduction

In this tutorial, you will learn how to create a Triangulated Irregular Network (TIN) from a 3D point dataset using the TINGenerator in FME. The TINGenerator in FME can create TINs from Points/Lines or Breaklines, whether the features are 2D or 3D.

Data Source

The source dataset is a point cloud containing elevation information. 

Step-by-step Instructions

In this scenario, you want to create a TIN because you are interested in draping 2D features on a 3D TIN. This tutorial will only cover TIN creation; if you are interested in learning how to drape imagery textures on terrain surfaces, read the Draping Imagery Textures on Terrain Surfaces article.

To follow along with this tutorial, please download the data from the article's Files section.

1. Create a New Workspace

Open FME Workbench and create a blank workspace. 

2. Add an ASPRS Lidar Data Exchange Format (LAS) Reader

Add a reader to the canvas by clicking on the Reader button on the top menu bar or by going to Readers > Add Reader. In the Add Reader dialog, set the following:

• Format: ASPRS Lidar Data Exchange Format (LAS)
• Dataset: ElevationPoints.las
  • Click on the ellipses to navigate to the location of the file on your computer

Click OK.

3. Create TIN

Add a TINGenerator transformer to the canvas by typing “TINGenerator” to bring up the list of FME Transformers in the Quick Add Search. Select the TINGenerator from the list of Transformers by double-clicking or using the arrow keys and Enter to add it. Ensure that the reader feature type is connected to the Points/Lines input port. 

Double-click on the TINGenerator to open the parameters. In the parameters, set:

• Surface Tolerance: 100

Click OK. 

The ElevationPoints dataset we are working with contains approximately 1.4 million elevation points. Without filtering out points, the TIN would be very jagged and require more processing power. To reduce the number of points used to create the TIN, we needed to specify a surface tolerance. A larger surface tolerance value will speed up surface model construction and simplify the TIN; the larger the value, the more input points will be filtered out. To learn more about Surface Tolerance values, see the TINGenerator Documentation.

4. Scale the Z Coordinate

Next, add a Scaler to the canvas and connect it to the TINSuraface output port on the TINGenerator. 

In the parameters, set the Z Scale Factor to 0.1, then click OK. 

The Z scale controls how high the features will be extruded from the ground. Lowering this will make the features look more realistic.

5. Run Workspace

Connect an Inspector transformer to the Scaler Scaled output port. 

Run the workspace by clicking the Run button on the top toolbar, or by selecting Run > Run Workspace from the top menu bar. 

After running the workspace, the output will be a 3D surface of the area's elevation.  

Data Attribution

The data used here originates from open data made available by the City of Vancouver, British Columbia. It contains information licensed under the Open Government License - Vancouver.