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.
Description: See J. Haber, F. Zeilfelder, O.Davydov and H.-P. Seidel, Smooth approximation and rendering of large scattered data sets, in 'Proceedings of IEEE Visualization 2001' (Th.Ertl, K.Joy and A.Varshney, Eds.), pp.341-347, 571, IEEE Computer Society, 2001.
www.uni-giessen.de/www-Numerische-Mathematik/davydov/VIS2001.ps.gz
www.math.uni-mannheim.de/~lsmath4/paper/VIS2001.pdf.gz
- Author: O. Conrad (c) 2008
- Menu: Grid|Gridding|Spline Interpolation
Parameters
| | Name | Type | Identifier | Description | Constraints |
|---|
| Input | Points | Shapes (input) | SHAPES | - | - |
| Target System (*) | Grid (optional input) | 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 | TARGET_USER_SIZE | - | Minimum: 0.000000
Default: 1.000000 |
| Left | Floating point | TARGET_USER_XMIN | - | Default: 0.000000 |
| Right | Floating point | TARGET_USER_XMAX | - | Default: 100.000000 |
| Bottom | Floating point | TARGET_USER_YMIN | - | Default: 0.000000 |
| Top | Floating point | TARGET_USER_YMAX | - | Default: 100.000000 |
| Fit | Choice | TARGET_USER_FITS | - | Available Choices:
[0] nodes
[1] cells
Default: 0 |
| Grid System | Grid system | TARGET_SYSTEM | - | - |
| Minimal Number of Points | Integer | NPMIN | - | Minimum: 0
Default: 3 |
| Maximal Number of Points | Integer | NPMAX | - | Minimum: 0
Maximum: 59
Default: 20 |
| Points per Square | Floating point | NPPC | - | Minimum: 0.000000
Default: 5.000000 |
| Tolerance | Integer | K | Spline sensitivity, reduce to get smoother results, recommended: 80 < Tolerance < 200 | Minimum: 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_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> 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)
-NPMIN:<num> Minimal Number of Points
Integer
Minimum: 0
Default: 3
-NPMAX:<num> Maximal Number of Points
Integer
Minimum: 0
Maximum: 59
Default: 20
-NPPC:<double> Points per Square
Floating point
Minimum: 0.000000
Default: 5.000000
-K:<num> Tolerance
Integer
Minimum: 0
Default: 140