Gridding - Honoring Data Input Values

You may find that your input data is not perfectly honored by the gridded data. This is because the input values have not been assigned to the grid nodes but have been used as a mathematical basis for assigning values to grid nodes.

This is characteristic of all computer mapping programs. Defaults in WinPICS will give you acceptable results in most cases, but you can change these defaults to better honor your data. Four main factors affect how well input data is honored:

Gridding Method

Some methods are better at honoring data points than others. These are:

Inverse Distance Weighting – Set the powerto 5 and set the smoothing to 0.
Triangulation – Set the interpolation to Linear Interpolation.

The other gridding methods do not honor the data values as closely, but may produce better-looking maps. To better honor the data while using these gridding methods, make the following changes to the parameters:

Kriging/Collocation – Select Quadric Model for the mathematical model, decrease the Half-Correlation Length, and set the Minimum Variance ofMeasurement to 0.
Minimum Curvature – Decrease the Maximum Iterations, increase the Maximum Residual, and initialize gridding.

Data Search Options

The Data Search Options define how many data points WinPICS will use and how it will search for these points in the grid node calculation. To honor your data points as closely as possible, limit the search function to fewer data points. This will shorten the distance from the grid node to the values used for calculating the grid node value.

Grid Geometry

The geometry of your grid defines the location of the grid nodes. A high grid density will more accurately honor your data. (But, keep in mind that dense grids require larger amounts of memory and longer time to calculate.) To honor your data, set the grid spacing fine enough to define the smallest features you wish to display on your map. It should also be fine enough to provide smooth contours so that you can avoid using the map smoothing function on your displays.

Map Window Smoothing Function

For the best correlation between gridded data and original data, be sure that you have the map smoothing function turned off (set to 1) when you display maps.

The map window smoothing settings stay active until you reset it or exit WinPICS .

What do you want to do?

Create a horizon grid