Now that we have seen how we can create the two main surface models, it is time to consider their use in answering queries about real-world surfaces. Again, it is important to remember that all our models are just that – models of the true surface. The degree to which the model is an accurate representation of the real surface will affect the degree to which the answers we get when using it reflect characteristics of the real surface.
We have already seen that many of the methods for interpolating a gridded DEM from elevation data give rise to artefacts which will clearly affect our results. In this chapter, we will see whether the results are also affected by the algorithms we use.