Search TipsThe linear interpolation and closest point process
This topic describes the functions of the Interpolate and Closest Point radio button selections that can be made in the Create Grid from Points dialog in the Scatter Grid command.
Interpolate
If the Interpolate radio button is selected Cadcorp SIS Desktop will interpolate a grid surface from existing item property values and a TIN will be created from the selected items:
The interpolation process will then create grid items in regard to the defined cell size in the Scatter Grid command Grid Creation dialog.
The location of the centroids inside the interpolation triangles is used to derive grid cell values from the TIN surface.
A linear Z interpolation of points inside a triangle is hereby applied.
The expression for this interpolation is given as:
Closest point
If the Closest Point radio button is selected a Thiessen Polygons layer will be created from the selected point items.
Cadcorp SIS Desktop will then assign the Z value of the Thiessen polygon to a Grid cell which centroid falls into the polygon.
Click here to return to Creating a Grid item using existing items
Click here to go to the Scatter Grid command.