SAGA-GIS Tool Library Documentation (v7.8.2)

Tool Cubic Spline Approximation

This tool approximates irregular scalar 2D data in specified points using C1-continuous bivariate cubic spline.
Minimal Number of Points: minimal number of points locally involved in spline calculation (normally = 3)

Maximal Number of Points:npmax: maximal number of points locally involved in spline calculation (required > 10, recommended 20 < npmax < 60)
Tolerance: relative tolerance multiple in fitting spline coefficients: the higher this value, the higher degree of the locally fitted spline (recommended 80 < k < 200)

Points per square: average number of points per square (increase if the point distribution is strongly non-uniform to get larger cells)

Author: Pavel Sakov, CSIRO Marine Research

Purpose: 2D data approximation with bivariate C1 cubic spline. A set of library functions + standalone utility.


References


Parameters

 NameTypeIdentifierDescriptionConstraints
InputPointsShapes, inputSHAPES--
Target System (*)Grid, input, optional, CMDTARGET_TEMPLATEuse this grid's system for output grids-
OutputTarget GridGrid, outputTARGET_OUT_GRID--
OptionsAttributeTable fieldFIELD--
Target Grid SystemChoiceTARGET_DEFINITION-Available Choices:
[0] user defined
[1] grid or grid system
Default: 0
CellsizeFloating pointTARGET_USER_SIZE-Minimum: 0.000000
Default: 1.000000
WestFloating pointTARGET_USER_XMIN-Default: 0.000000
EastFloating pointTARGET_USER_XMAX-Default: 100.000000
SouthFloating pointTARGET_USER_YMIN-Default: 0.000000
NorthFloating pointTARGET_USER_YMAX-Default: 100.000000
ColumnsIntegerTARGET_USER_COLSNumber of cells in East-West direction.Minimum: 1
Default: 100
RowsIntegerTARGET_USER_ROWSNumber of cells in North-South direction.Minimum: 1
Default: 100
FitChoiceTARGET_USER_FITS-Available Choices:
[0] nodes
[1] cells
Default: 0
Grid SystemGrid systemTARGET_SYSTEM--
Minimal Number of PointsIntegerNPMIN-Minimum: 0
Default: 3
Maximal Number of PointsIntegerNPMAX-Minimum: 11
Maximum: 59
Default: 20
Points per SquareFloating pointNPPC-Minimum: 1.000000
Default: 5.000000
ToleranceIntegerKSpline sensitivity, reduce to get smoother results, recommended: 80 < Tolerance < 200Minimum: 0
Default: 140
(*) optional

Command-line

Usage: saga_cmd grid_spline 6 [-SHAPES <str>] [-FIELD <str>] [-TARGET_DEFINITION <str>] [-TARGET_USER_SIZE <double>] [-TARGET_USER_XMIN <double>] [-TARGET_USER_XMAX <double>] [-TARGET_USER_YMIN <double>] [-TARGET_USER_YMAX <double>] [-TARGET_USER_COLS <num>] [-TARGET_USER_ROWS <num>] [-TARGET_USER_FITS <str>] [-TARGET_TEMPLATE <str>] [-TARGET_OUT_GRID <str>] [-NPMIN <num>] [-NPMAX <num>] [-NPPC <double>] [-K <num>]
  -SHAPES:<str>             	Points
	Shapes, input
  -FIELD:<str>              	Attribute
	Table field
  -TARGET_DEFINITION:<str>  	Target Grid System
	Choice
	Available Choices:
	[0] user defined
	[1] grid or grid system
	Default: 0
  -TARGET_USER_SIZE:<double>	Cellsize
	Floating point
	Minimum: 0.000000
	Default: 1.000000
  -TARGET_USER_XMIN:<double>	West
	Floating point
	Default: 0.000000
  -TARGET_USER_XMAX:<double>	East
	Floating point
	Default: 100.000000
  -TARGET_USER_YMIN:<double>	South
	Floating point
	Default: 0.000000
  -TARGET_USER_YMAX:<double>	North
	Floating point
	Default: 100.000000
  -TARGET_USER_COLS:<num>   	Columns
	Integer
	Minimum: 1
	Default: 100
  -TARGET_USER_ROWS:<num>   	Rows
	Integer
	Minimum: 1
	Default: 100
  -TARGET_USER_FITS:<str>   	Fit
	Choice
	Available Choices:
	[0] nodes
	[1] cells
	Default: 0
  -TARGET_TEMPLATE:<str>    	Target System
	Grid, input, optional, CMD
  -TARGET_OUT_GRID:<str>    	Target Grid
	Grid, output
  -NPMIN:<num>              	Minimal Number of Points
	Integer
	Minimum: 0
	Default: 3
  -NPMAX:<num>              	Maximal Number of Points
	Integer
	Minimum: 11
	Maximum: 59
	Default: 20
  -NPPC:<double>            	Points per Square
	Floating point
	Minimum: 1.000000
	Default: 5.000000
  -K:<num>                  	Tolerance
	Integer
	Minimum: 0
	Default: 140