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
- 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.
- Author: O. Conrad (c) 2008
- Menu: Grid|Gridding|Spline Interpolation
Parameters
| Name | Type | Identifier | Description | Constraints |
Input | Points | Shapes, input | SHAPES | - | - |
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 | TARGET_USER_SIZE | - | Minimum: 0.000000 Default: 1.000000 |
West | Floating point | TARGET_USER_XMIN | - | Default: 0.000000 |
East | Floating point | TARGET_USER_XMAX | - | Default: 100.000000 |
South | Floating point | TARGET_USER_YMIN | - | Default: 0.000000 |
North | Floating point | TARGET_USER_YMAX | - | Default: 100.000000 |
Columns | Integer | TARGET_USER_COLS | Number of cells in East-West direction. | Minimum: 1 Default: 100 |
Rows | Integer | TARGET_USER_ROWS | Number of cells in North-South direction. | Minimum: 1 Default: 100 |
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: 11 Maximum: 59 Default: 20 |
Points per Square | Floating point | NPPC | - | Minimum: 1.000000 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_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