SAGA-GIS Module Library Documentation (v2.3.0)

Module Multilevel B-Spline Interpolation (from Grid)

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

Parameters

 NameTypeIdentifierDescriptionConstraints
InputGridGrid (input)GRID--
Target System (*)Grid (optional input)TARGET_TEMPLATEuse this grid's system for output grids-
OutputTarget GridGrid (output)TARGET_OUT_GRID--
OptionsGrid systemGrid systemGRID_GRIDSYSTEM--
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
LeftFloating pointTARGET_USER_XMIN-Default: 0.000000
RightFloating pointTARGET_USER_XMAX-Default: 100.000000
BottomFloating pointTARGET_USER_YMIN-Default: 0.000000
TopFloating pointTARGET_USER_YMAX-Default: 100.000000
FitChoiceTARGET_USER_FITS-Available Choices:
[0] nodes
[1] cells
Default: 0
Grid SystemGrid systemTARGET_SYSTEM--
MethodChoiceMETHOD-Available Choices:
[0] without B-spline refinement
[1] with B-spline refinement
Default: 1
Threshold ErrorFloating pointEPSILON-Minimum: 0.000000
Default: 0.000100
Maximum LevelIntegerLEVEL_MAX-Minimum: 1
Maximum: 14
Default: 11
Update ViewBooleanUPDATE-Default: 0
Data TypeChoiceDATATYPE-Available Choices:
[0] same as input grid
[1] floating point
Default: 1
(*) optional

Command-line

Usage: saga_cmd grid_spline 5 [-GRID <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_FITS <str>] [-TARGET_TEMPLATE <str>] [-TARGET_OUT_GRID <str>] [-METHOD <str>] [-EPSILON <double>] [-LEVEL_MAX <num>] [-UPDATE <str>] [-DATATYPE <str>]
  -GRID:<str>               	Grid
	Grid (input)
  -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>	Left
	Floating point
	Default: 0.000000
  -TARGET_USER_XMAX:<double>	Right
	Floating point
	Default: 100.000000
  -TARGET_USER_YMIN:<double>	Bottom
	Floating point
	Default: 0.000000
  -TARGET_USER_YMAX:<double>	Top
	Floating point
	Default: 100.000000
  -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)
  -METHOD:<str>             	Method
	Choice
	Available Choices:
	[0] without B-spline refinement
	[1] with B-spline refinement
	Default: 1
  -EPSILON:<double>         	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
  -DATATYPE:<str>           	Data Type
	Choice
	Available Choices:
	[0] same as input grid
	[1] floating point
	Default: 1