THE SIGNIFICANT ROLE THAT TINS PLAY IN CIVIL ENGINEERING

Geometry is the basis for civil engineering. You may have heard the term TIN when speaking with a civil engineer about a surface model for your project. So, what is this TIN thing you hear them talking about?  Basically, it’s a bunch of triangles all joined continuously together at their points (vertices). TINs provide a visual of a topographical surface and are the building blocks for creating 3D surface models of civil works.

Where does TIN come from?

Different techniques can create the triangle’s vertices, including surveying, Global Positioning System Real-Time Kinematic (GPS RTK), photogrammetry, and more. The elevations data associated with the recorded spots captured from any of those methods give you the vertices of the triangles. When irregularly distributed nodes and lines with 3D coordinates (x, y, z) are arranged in a network of non-overlapping triangles, you have a TIN representing the land’s surface used for modeling civil (and architectural) work. The triangles are all flat planes. They can be of varied sizes and set into different configurations, but they do not overlap.

What is TIN based on?

TIN is based on a Delaunay triangulation. That means that no vertex lies within the interior of any of the circumcircles within the network of triangles. Therefore, there are as few long, thin triangles as possible, which gives you a higher precision model. Using TIN for designing digital elevation models (DEMS) is advantageous because the TIN points accurately represent the underlying terrain that exists. It is common for the TIN to be used for creating contour lines using CAD. Contour lines are imaginary yet essential in our work because they represent elevations in the earth’s topography. They join points of equal elevation and allow you to determine the heights and steepness of hills and mountains as well as the depths of lakes and oceans.

How do civil engineers use TIN?

When designing a 3d model, many factors are considered for creating and reviewing a good working model. A virtual construction engineer (VCE) will first use the contour lines provided by the engineer to develop the basic TIN. The contour line is the backbone of the TIN. Next, the breaklines for the curbs, building pads, and other features are added to the TIN. Lastly, the VCE will tune the TIN by adding breaklines and additional points wherever it appears that the TIN is not reflecting the engineer’s intent. A VCE also must be mindful that many machine GPS control boxes cannot handle highly complex or large TIN files. That fact is important and requires excellent attention to detail because control boxes will become bogged down and will have difficulty performing if the surface and size of the triangles are not optimally balanced. Close attention must also be paid to how water will flow, and checks must be done to ensure drainage areas are ideal. Understanding ADA specifications are also critical and must be factored into the 3d model because an oversight there could be costly.

TIN knowledge isn’t necessarily in everyone’s toolbox, but it is an important tool in ours! When you require high-quality 3d models for your construction projects, contact ECI Technologies. Our virtual construction engineers are ready to lend a hand and are always available to answer questions. They take the time to understand your needs to deliver high-quality models on time and on budget!