grp - Grid points and lines

Name

grp — Grid points and lines

Syntax

grp [inc] | [nx ny] | [long] [sca] [ref] [csf] [aux] [ssf] [ssfdis] [rad] [trg] [pav] [mav] [exc] [log] [son] [2dc] [nsc] [mnp] [mrf] [cvf] [2d] [fast] [ext] [int]

Description

General gridding command from input points and lines into a grid surface. Default is parabolic interpolation.

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.

sca

Result grid is polydata and the scalars will be gridded in an extra pass and put into the scalar part of the poly grid.

trg [gri]

End up with polydata grid and a triangualtion model toward faults. Make a grid also when gri is given.

ref reference_grid

Use a reference_grid in workspace to tell the layout of the result grid.

csf closed_stick_faults

Use closed_stick_faults in workspace as input to gridding.

aux help_lines

Help lines to be used together with csf option.

ssf single_stick_faults

Use single_stick_faults traces without values in workspace as input.

ssfdis split_distance

Optional split_distance of single_stick_faults.

rad radius

Use a radius value for max interpolation distance.

pav

Interpolation is a blend of parabolic and moving average.

mav

Moving average is used for interpolation.

smo smoothstrength

Will use smoothing of cube at end of gridding.

exc [value] | [nod 'number_of_nodes']

Exclude points at grid nodes closer than value (or specify number of nodes) to achieve a smoothing effect. If value or nod is omitted only the grid node to be smoothed is excluded and the 8 remaining grid nodes in the 3x3 grid node pattern (default) are used to evaluate the grid node using the parabolic interpolator unless the mav argument is used. grp exc is often run as an extra smoothing step after the gridding.

exc [value] neb

Smoothes like grp exc but will not smooth at the border (no exclude points at border). Thus with this argument one can extract a part of a grid and smooth it with grp exc neb and insert it into the grid (using rep lo grid) without having any unpleasant transition zone where the grid is inserted.

log log_number

List info in message area. Gives a message for each log_number grid line.

son

Use sonar sorting of input. This is default for size of input points greater than 1000.

2dc

Input is 2D contour lines with values.

2d

Input is 2D lines f.inst. from seismic.

nsc number_of_sectors

For sort grid aplication: number_of_sectors used in interpolation.

mnp max_number_of_points

For sort grid application: max_number_of_points used in interpolation.

cvf closed_value_faults

Use closed_value_faults traces with values in workspace as input.

fast

Fast gridding. Internal parameters are trimmed to give a fast result.

ext [par | mav] [ref referencegrid]

Extrapolate a grid inside the outline of the grid. Input is a grid. Will use the CMOS algorithm for a smoother extrapolation as default.
par | mav - Will use the parabolic or moving average algorithm for faster performance.
ref referencegrid - Apply the reference grid referencegrid to tell where the extrapolation should be done. Any referencegrid that does not match input grid in size will lead to the following error message (as an example):

"2034558 2867380 Unequal number of points in the two grids

while executing

grp ext ref referencegrid"

int [par] [poi points] [cpo closedpolygons] [ext]

Interpolate holes in a grid. Input is a grid. Default interpolator is the CMOS algorithm for a smoother interpolation.
par - Use parabolic algorithm for quick solution if only very small holes.
poi points - Interpolate only holes where a point is present in workspace data points.
cpo closedpolygons - Interpolate only holes where a closed polygon is present in workspace data closedpolygons.
ext - will first perform interpolation to fill in interior holes; then extrapolation to extrapolate until grid frame.

mrf

See argument mrf in the son command.

Examples

Ex.1: Point gridding

mak ran 11      ;# Make 11 random points
grp 50 50       ;# Make a grid of 50 50 nodes

# Point model gridding
z                 ;# Erase screen
win demo          ;# Get demo window (450000 460000 6450000 6460000 1000 4000)
mak ran 22        ;# Make random points
poi               ;# Display points
grp 70 70         ;# Make grid
map               ;# Misplay map
cco map rev tit {Depth} ; # color code type map, reverse color and title

The above example produces this image.

Examples of parabolic gridding

Ex.2: Interpolation of interior holes

To test the command grp int one can try the following script. Go to File > New Text Editor and paste in the script. Then right click and perform Execute.

xwi sel          ;# force the graphic window in front
z                ;# erase the screen
vie 2 1 1        ;# make 2 x 1 viewports and select the first
win demo         ;# make demo window
mak ran 222 z 1000 4000     ;# Make 222 random points between 1000 and 4000
grp 333 444      ;# Make a grid of 333 x 444 nodes
eli lt 1500      ;# eliminate lower than 1500
mhi gg           ;# save in gg
acm s 1750 500 4000 ;# color bands starting from 1750 and step by 500
sma i 125        ;# spline contours with increment 125
vie 2 con        ;# select viewport 2 and connect to 1
grp int          ;# grid and interpolate holes
acm s 1750 500 4000 ;# color bands starting from 1750 and step by 500
sma i 125        ;# spline contours with increment 125