This exercise shows how GCD can be used to produce a multi-method error surface for a hybrid survey. A hybrid survey is simply a term we use for surveys and DEMs that are derived from topographic surveys that involved the use of multiple survey methods (e.g. total station, ariborne LiDaR and multi-beam SONAR). One of the problems with hybrid surveys is that modeling elevation uncertainty might require a different approach for each survey method. How do we mix and match different methods, yet keep all the analysis together in one clean package? The GCD software now supports this increasingly common dilema. In this segment we will cover how to do this.