Changes

==Rectangular gridding==

==Rectangular gridding==

[[file:introduction-to-contouring-geological-data-with-a-computer_fig6.png|thumb|{{figure number|6}}A13 × 13 grid showing the relationship between grid nodes and control points for the Davis<ref name=pt08r6 /> data set.]]

[[file:introduction-to-contouring-geological-data-with-a-computer_fig6.png|300px|thumb|{{figure number|6}}A13 × 13 grid showing the relationship between grid nodes and control points for the Davis<ref name=pt08r6 /> data set.]]

Rectangular gridding, in contrast to triangulation, first uses data at measured control points to interpolate values to a set of grid nodes at a predefined spacing. These values are then used to estimate positions of contours crossing each grid rectangle. The complete surface is assembled from contiguous grid rectangles. For most geological applications, grid squares are used rather than the more general rectangle. Interpolation and contouring of an irregularly spaced control point set on a rectangular grid requires many decisions from the geologist.

Rectangular gridding, in contrast to triangulation, first uses data at measured control points to interpolate values to a set of grid nodes at a predefined spacing. These values are then used to estimate positions of contours crossing each grid rectangle. The complete surface is assembled from contiguous grid rectangles. For most geological applications, grid squares are used rather than the more general rectangle. Interpolation and contouring of an irregularly spaced control point set on a rectangular grid requires many decisions from the geologist.