Cubic Spline Approximation

Author: O. Conrad (c) 2008
Menu: Grid | Gridding | Spline Interpolation

Description

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

Haber, J., Zeilfelder, F., Davydov, O., Seidel, H.-P. (2001): Smooth approximation and rendering of large scattered data sets. In Ertl, T., Joy, K., Varshney, A. [Eds.]: Proceedings of IEEE Visualization. pp.341-347, 571, IEEE Computer Society.

Parameters

	Name	Type	Identifier	Description	Constraints
Input	Points	shapes, input	`SHAPES`	-	-
Input	Target System	grid, input, optional, CMD	`TARGET_TEMPLATE`	use this grid's system for output grids	-
Output	Target Grid	grid, output	`TARGET_OUT_GRID`	-	-
Options	Attribute	table field	`FIELD`	-	-
	Target Grid System	choice	`TARGET_DEFINITION`	-	Available Choices: [0] user defined [1] grid or grid system Default: 0
	Cellsize	floating point number	`TARGET_USER_SIZE`	-	Minimum: 0.000000 Default: 1.000000
	West	floating point number	`TARGET_USER_XMIN`	-	Default: 0.000000
	East	floating point number	`TARGET_USER_XMAX`	-	Default: 100.000000
	South	floating point number	`TARGET_USER_YMIN`	-	Default: 0.000000
	North	floating point number	`TARGET_USER_YMAX`	-	Default: 100.000000
	Columns	integer number	`TARGET_USER_COLS`	Number of cells in East-West direction.	Minimum: 1 Default: 101
	Rows	integer number	`TARGET_USER_ROWS`	Number of cells in North-South direction.	Minimum: 1 Default: 101
	Fit	choice	`TARGET_USER_FITS`	-	Available Choices: [0] nodes [1] cells Default: 0
	Grid System	grid system	`TARGET_SYSTEM`	-	-
	Minimal Number of Points	integer number	`NPMIN`	-	Minimum: 0 Default: 3
	Maximal Number of Points	integer number	`NPMAX`	-	Minimum: 11 Maximum: 59 Default: 20
	Points per Square	floating point number	`NPPC`	-	Minimum: 1.000000 Default: 5.000000
	Tolerance	integer number	`K`	Spline sensitivity, reduce to get smoother results, recommended: 80 < Tolerance < 200	Minimum: 0 Default: 140

Command Line

Usage: saga_cmd grid_spline 6 [-SHAPES ] [-FIELD ] [-TARGET_DEFINITION ] [-TARGET_USER_SIZE ] [-TARGET_USER_XMIN ] [-TARGET_USER_XMAX ] [-TARGET_USER_YMIN ] [-TARGET_USER_YMAX ] [-TARGET_USER_COLS ] [-TARGET_USER_ROWS ] [-TARGET_USER_FITS ] [-TARGET_TEMPLATE ] [-TARGET_OUT_GRID ] [-NPMIN ] [-NPMAX ] [-NPPC ] [-K ]
  -SHAPES:             	Points
	shapes, input
  -FIELD:              	Attribute
	table field
  -TARGET_DEFINITION:  	Target Grid System
	choice
	Available Choices:
	[0] user defined
	[1] grid or grid system
	Default: 0
  -TARGET_USER_SIZE:	Cellsize
	floating point number
	Minimum: 0.000000
	Default: 1.000000
  -TARGET_USER_XMIN:	West
	floating point number
	Default: 0.000000
  -TARGET_USER_XMAX:	East
	floating point number
	Default: 100.000000
  -TARGET_USER_YMIN:	South
	floating point number
	Default: 0.000000
  -TARGET_USER_YMAX:	North
	floating point number
	Default: 100.000000
  -TARGET_USER_COLS:   	Columns
	integer number
	Minimum: 1
	Default: 101
  -TARGET_USER_ROWS:   	Rows
	integer number
	Minimum: 1
	Default: 101
  -TARGET_USER_FITS:   	Fit
	choice
	Available Choices:
	[0] nodes
	[1] cells
	Default: 0
  -TARGET_TEMPLATE:    	Target System
	grid, input, optional, CMD
  -TARGET_OUT_GRID:    	Target Grid
	grid, output
  -NPMIN:              	Minimal Number of Points
	integer number
	Minimum: 0
	Default: 3
  -NPMAX:              	Maximal Number of Points
	integer number
	Minimum: 11
	Maximum: 59
	Default: 20
  -NPPC:            	Points per Square
	floating point number
	Minimum: 1.000000
	Default: 5.000000
  -K:                  	Tolerance
	integer number
	Minimum: 0
	Default: 140