Module Multilevel B-Spline Interpolation

Multilevel B-spline algorithm for spatial interpolation of scattered data as proposed by Lee, Wolberg and Shin (1997). The algorithm makes use of a coarse-to-fine hierarchy of control lattices to generate a sequence of bicubic B-spline functions, whose sum approaches the desired interpolation function. Large performance gains are realized by using B-spline refinement to reduce the sum of these functions into one equivalent B-spline function.

The 'Maximum Level' determines the maximum size of the final B-spline matrix and increases exponential with each level. Where level=10 requires about 1mb level=12 needs about 16mb and level=14 about 256mb(!) of additional memory.

Reference:
- Lee, S., Wolberg, G., Shin, S.Y. (1997): 'Scattered Data Interpolation with Multilevel B-Splines', IEEE Transactions On Visualisation And Computer Graphics, Vol.3, No.3

Author: (c) 2006 by O.Conrad
Specification: grid
Menu: Grid|Gridding|Spline Interpolation

Parameters

	Name	Type	Identifier	Description	Constraints
Input	Points	Shapes (input)	`SHAPES`	-	-
Options	Attribute	Table field	`FIELD`	-	-
	Method	Choice	`METHOD`	-	Available Choices: [0] without B-spline refinement [1] with B-spline refinement Default: 1
	Threshold Error	Floating point	`EPSILON`	-	Minimum: 0.000000 Default: 0.000100
	Maximum Level	Integer	`LEVEL_MAX`	-	Minimum: 1 Maximum: 14 Default: 11
	Update View	Boolean	`UPDATE`	-	Default: 0

Command-line

Usage: saga_cmd grid_spline 4 -SHAPES <str> [-FIELD <str>] [-METHOD <str>] [-EPSILON <str>] [-LEVEL_MAX <num>] [-UPDATE <str>] [-TARGET_DEFINITION <str>] [-TARGET_USER_XMIN <str>] [-TARGET_USER_XMAX <str>] [-TARGET_USER_YMIN <str>] [-TARGET_USER_YMAX <str>] [-TARGET_USER_SIZE <str>] [-TARGET_USER_FITS <str>] [-TARGET_TEMPLATE <str>] [-TARGET_OUT_GRID <str>]
  -SHAPES:<str>           	Points
	Shapes (input)
  -FIELD:<str>            	Attribute
	Table field
  -METHOD:<str>           	Method
	Choice
	Available Choices:
	[0] without B-spline refinement
	[1] with B-spline refinement
	Default: 1
  -EPSILON:<str>          	Threshold Error
	Floating point
	Minimum: 0.000000
	Default: 0.000100
  -LEVEL_MAX:<num>        	Maximum Level
	Integer
	Minimum: 1
	Maximum: 14
	Default: 11
  -UPDATE:<str>           	Update View
	Boolean
	Default: 0
  -TARGET_DEFINITION:<str>	Target Grid System
	Choice
	Available Choices:
	[0] user defined
	[1] grid or grid system
	Default: 0
  -TARGET_USER_XMIN:<str> 	Left
	Floating point
	Default: 0.000000
  -TARGET_USER_XMAX:<str> 	Right
	Floating point
	Default: 100.000000
  -TARGET_USER_YMIN:<str> 	Bottom
	Floating point
	Default: 0.000000
  -TARGET_USER_YMAX:<str> 	Top
	Floating point
	Default: 100.000000
  -TARGET_USER_SIZE:<str> 	Cellsize
	Floating point
	Minimum: 0.000000
	Default: 1.000000
  -TARGET_USER_FITS:<str> 	Fit
	Choice
	Available Choices:
	[0] nodes
	[1] cells
	Default: 0
  -TARGET_TEMPLATE:<str>  	Target System
	Grid (optional input)
  -TARGET_OUT_GRID:<str>  	Target Grid
	Grid (output)