Most computer mapping systems build a surface model using only data for that surface. When one surface laps onto or truncates another, the initial surface models will almost always cross ([[:file:using-and-improving-surface-models-built-by-computer_fig8.png|Figure 8]]). This is expected and must be corrected. The following discussion describes methods for handling baselap and truncation in a grid-based mapping system. | Most computer mapping systems build a surface model using only data for that surface. When one surface laps onto or truncates another, the initial surface models will almost always cross ([[:file:using-and-improving-surface-models-built-by-computer_fig8.png|Figure 8]]). This is expected and must be corrected. The following discussion describes methods for handling baselap and truncation in a grid-based mapping system. |