Files
Introduction
Triangular irregular networks (TIN) represent a continuous surface with a set of non-overlapping triangles. FME supports Solid and Surface clipping, making it easier than ever to quickly clip data to the desired area.
Step-by-Step Instructions
1. Read in the DEM
Open FME Workbench and in a blank workspace, add a U.S. Geological Survey Digital Elevation Model (USGSDEM) reader and read in the source raster data, RasterDEM-250k.dem, which is available for download in the Files section.
2. Create TIN from the Raster with TINGenerator
To create a TIN from the raster, we need to use a TINGenerator transformer. Add a TINGenerator to the canvas and connect the Points/Lines input port to the USGS_DEM reader feature type.
In the parameters, set the Surface Tolerance parameter to 5, which determines the number of points used as the surface model's vertices. The larger the value, the more input points will be filtered out.
3. Create an Irregular Boundary for Clipping
We will use a polygon as our clipping boundary. Add a Shapefile reader to the canvas and browse to the ClippingBoundary.zip file. This boundary is just a randomly generated polygon to demonstrate this example.
4. Clip Surface
Add a Clipper to the canvas and connect the ClippingBoundary reader feature type to the Clipper input port, then the TINSurface output port on the TINGenerator to the Candidate input port on the Clipper.
To uncross the connection lines, right-click on the Clipper input port and select Move Down.
5. Inspect Output
Connect an Inspector transformer to the Clipper's Inside output port, then run the workspace. View the output in Data Preview (formerly Visual Preview).
Data Attribution
The data used in this article originates from open data made available by the City of Austin, Texas. It contains data licensed under the Public Domain Dedication License, as provided by the City of Austin.