Moving surface

Dialog box

The Moving surface operation is a point interpolation which requires a point map as input and returns a raster map as output. For each output pixel, a polynomial surface is calculated by a least squares fit; for each output pixel, the surface will approach the weighted point values of the points which fall within the specified limiting distance. The calculated surface values are assigned to the output pixels. You have to specify a weight function, a value for the limiting distance and a function with which surfaces have to be calculated. For more information, refer to Moving surface : functionality.

Dialog box options:

Input point map:	Select an input point map. Open the list box and select the desired input map, or drag a point map directly from the Catalog into this box. You can select a point map with a value domain, or a point map with a class or ID domain which has a linked attribute table with values (then select an attribute column with a value domain).
Weight function:	Select the weight function which should be used to calculate weight factors for the points. Both weight functions ensure that points close to an output pixel will obtain a larger weight factor than points which are farther away. The inverse distance method assigns relatively larger weights to points close to an output pixel than the linear decrease method. For more information on weight functions, see Moving surface : algorithm.
Inverse distance:	(1 / dⁿ ) - 1
Linear decrease:	1 - dⁿ
	d = relative distance of points towards pixels n = weight exponent
Weight exponent:	Type a value for weight exponent n to be used in the selected weight function (real value, usually a value close to 1.0).
Limiting distance:	Type a value for the limiting distance. Points that are farther away from any output pixel than the limiting distance, are assigned weight zero; the values of these points will thus not be used in the calculation of the output value for that pixel.
Use spherical distance:	Select this check box to calculate with spherical distances, i.e. distances are calculated over the sphere using the projection of the coordinate system of the georeference of the output raster map. It is advised to select this option in case your map covers a relatively large area, or when you are working in LatLon coordinates. For more information, see Moving surface : functionality. Clear this check box to calculate with planar (Euclidean) distances.
Surface:	Select one of the 8 functions to calculate for each output pixel a surface which approaching all points within the limiting distance towards this output pixel.
Output raster map:	Type the name of the output raster map.
Georeference:	Type the name of an existing georeference or create a new georeference.
Value range:	Accept the default value range, or specify your own range of possible values in the output map.
Precision:	Accept the default precision of output values, or specify your own precision.
Description:	Optionally, type a description for the output map. The description will appear in the status bar of the Main window when moving the mouse pointer over the map in a Catalog, and in the title bar of a map window when the output map is displayed. If no description is supplied, the output map will use its own definition as description.

When you click the Show button, the dependent output map will be defined, calculated and shown. When you click the Define button, the dependent output map will only be defined; if necessary, the map will be calculated later, for instance when the map is opened to be displayed.