son - Sonar data gridding

Name

son — Sonar data gridding

Syntax

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 inside other boundaries in the set of boundary lines.

fast pregriddingfactor

Will speed up gridding using a pregriddingfactor between 1 and 30.

cps surfacename

Check points towards surface in surfacename to get the difference between points and surface. Standard deviation and mean is calculated and saved in [gvar standev] and [gvar mean].  A standard deviation data set is generated in workspace standev.

cpr surfacename [def factor | \[lovalue] [hivalue] ]

Check points towards surface in surfacename to get the difference between points and surface. Remove points outside a low and high value which can be factor * standard_deviation using the def argument or directly specified by values lovalue hivalue. The remaining points are left in active.

lst

Will list the current parameters used in sonar spiral sort gridding.

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