Surveying ME - BMEEOAFM201

Digital Terrain Models - DTM

Triangulated Irregular Network - TIN

Digital Elevation Model - DEM

Digital Surface Model - DSM

Diamond → brilliant

Steps of developing a TIN-model

1. definition of its border
2. definition of triangles, automatically with some optimization, sometimes with given breaklines as constraints
   
3. swap triangles if necessary. See the embankment example.
   
4. delete unnecessary points or triangles if necessary

Applications of TIN-models

1. interpolation: get the reduced level in a point which was not surveyed before. Linear interpolation is used along the plane defined by three points
2. drawing sections: determining the section of a vertical plane and the TIN-model. Only those triangles need to be taken into account which has intersections with the vertical plane.
3. drawing contour lines: determining the section of a horizontal plane and the TIN model. The height of the horizontal plane is the reduced level of the contour line. 
4. creating a grid model: the grid is defined by its origin and grid sizes. Interpolation has to be carried out in the grid points.
5. comparison of different TIN-models: interpolate elevation using the second TIN-model in the points of the first TIN-model. The difference model is again a TIN-model
6. volume computation: see next lecture.

Drawing contour lines

1. Generate contour lines from the TIN-model automatically as sections of the TIN-model and horizontal planes. The result is a series of lines.
   
2. Join the lines into polylines, convert polylines into splines
   
3. Label them with RL values