Name
son — Sonar data gridding
Syntax
son ppg [inc] | [nx ny] | [long] [all | four] [tri] [eig] [eigone] [low] [hi] [dob] [auto] [count] [mrf]
Description
Specialized command for gridding sonar data or large point sets. The son without the ppg option is covered by the command grp .
The son ppg is a snapping algorithm of input points to the grid result. The algorithm will snap free point data into a grid of size nx ny. The snap gridding will make defined grid nodes of each node that is closest to an input point. If more than one point are sorted to a node, the node value will be the average of the point values. A count grid telling the number of coincident points can be generated.
Arguments
No arguments, the grid will have the same number of rows and columns as the last grid that set the @nrow @ncol variables.
inc xinc yinc
Create grid model grid with increments xinc and yinc .
nx ny
Create a grid with nx times ny grid cells.
long num
Create a grid with num nodes for the longest side. Use the same increment for the shortest side.
tri
The three nearest nodes will be used.
all | four
All four nodes surrounding a point will be used.
eig
All eigth nodes surrounding a point including the nearest will be used.
eigone
All eigth nodes surrounding a point will be used and the value 1 will be placed.
low
If coincident points, the lowest will be used and placed in the nearest node.
hi
If coincident points, the highest will be used and placed in the nearest node.
dob
Double check that the first point will be placed in the nearest node and the next coinciding in the three nearest.
auto
The x and y increments are found from the input points. Useful for cases where the input points already are orginized in a grid system.
count
The generated grid will have the counting of coincident points.
mrf
Make reference grid (boundary grid) and reference line around a point set. The reference grid is saved in active and the reference line is saved in workspace refLine. Look at the options for detailed control.
mrf num
Create a boundary grid with num nodes for the sides. Points within the boundary grid will define the boundary.
mrf bou nx ny [nodraw]
Create a boundary grid with nx ny nodes for the sides. Points within the boundary grid will define the boundary. The nodraw option will prevent the derived boundary line to de drawn.
mrf dis distance
Create a boundary grid so that points separated less than distance will be within the same boundary.
mrf ... [abx]
Will remove interior boundaries in the set of boundary lines.
Examples
Ex.1: Snap gridding of points
# Snap model gridding z ;# Erase screen win demo ;# Get demo window (450000 460000 6450000 6460000 1000 4000) spe bgc whi ;# Specify background color to white mak ran 55 ;# Make 55 random points poi ;# Display points son ppg 9 9 ;# Make grid of dimension poi 2 ;# Display grid points map ;# Map the grid und 0 ;# Make all undefined cells to 0 poll ;# Draw the grid lines
The above example produces this image.
The example demonstrates how the snapping is performed
Snap gridding showing input points (black) and grid points (red)
See also
grp - Grid points and lines, fmo - Fast modelling