Changes

Most mapping systems have many parameter switches to adjust surface modeling algorithms. Only a few are frequently used to improve the model, but the ones used often make drastic improvements. Parameters found to be useful affect items such as amount of smoothing, number of data points required, number of sectors (compass directions from which data are used) that must have data, distance to look for data, type of algorithm used, type of filter used, size of grid increment, and whether a coarse regional model is built and refined to the desired detail.

Most mapping systems have many parameter switches to adjust surface modeling algorithms. Only a few are frequently used to improve the model, but the ones used often make drastic improvements. Parameters found to be useful affect items such as amount of smoothing, number of data points required, number of sectors (compass directions from which data are used) that must have data, distance to look for data, type of algorithm used, type of filter used, size of grid increment, and whether a coarse regional model is built and refined to the desired detail.

[[file:using-and-improving-surface-models-built-by-computer_fig3.png|thumb|left|{{figure number|3}}Cross sections through the same data. (a) Extrapolated values for a weighted average algorithm tend to “come back” to the average of near data values. (b) Acceptable surface extrapolation achieved by creating a first-order trend, modeling residuals between data and trend, and adding the trend and residual surfaces.]]

[[file:using-and-improving-surface-models-built-by-computer_fig3.png|thumb|300px|{{figure number|3}}Cross sections through the same data. (a) Extrapolated values for a weighted average algorithm tend to “come back” to the average of near data values. (b) Acceptable surface extrapolation achieved by creating a first-order trend, modeling residuals between data and trend, and adding the trend and residual surfaces.]]

===Rebuild using multiple step modeling methods===

===Rebuild using multiple step modeling methods===