Water Resources Applications Software
Summary of CONTOUR
NAME
contour - A contouring program for gridded data
ABSTRACT
CONTOUR is designed for use with finite-difference models such as
MODFLOW. It works with uniform or variably spaced grids. Input
data can be formatted data from most models or unformatted data from
MODFLOW.
METHOD
Data to be contoured are a two-dimensional array of values, which
are Z values for each node in a grid. A contour line is formed by
connecting successive contour points with straight lines. Branches
connect adjacent nodes. Contour points occur only on Branches. If
the value being contoured is between the Z values at two adjacent
nodes, the connecting branch contains a contour point. Linear
interpolation is used to find the location of a contour point on a
branch. Unlike many contouring packages, CONTOUR does not create a
fine uniform grid and interpolate values for each point in that
grid. CONTOUR also does not smooth the lines. Thus, if a grid is
coarse, the contours will be coarse. Because CONTOUR does not
generate a new grid or smooth lines, it uses minimal computational
resources.
HISTORY
Version 2.5 96/01/24 - Current release for Data General workstations
(split routines that produce graphics through call to GKS from
main code group)
Version 2.4 95/08/08 - Increased dimension of arrays
Version 91/11/15 - First release for Data General workstations
Version 89/xx/xx - Original published version
DATA REQUIREMENTS
The user is prompted interactively for grid spacing, data to be
contoured, and contour values. There are also prompts to control
options such as scaling, the display of the grid, and plotting of
values at each grid point.
OUTPUT OPTIONS
The output is a contour plot.
SYSTEM REQUIREMENTS
CONTOUR is written in Fortran 77 with the following extensions: use
of integer*2 and integer*4 declarations. Graphics are coded using
the Graphical Kernel System (GKS) library references. Generally,
the program is easily installed on most computer systems that have
access to a GKS graphics library. The code has been used on UNIX-
based computers.
DOCUMENTATION
Harbaugh, A.W., 1990, A simple contouring program for gridded data:
U.S. Geological Survey Open-File Report 90-144, 37 p.
CONTACTS
Operation and Distribution:
U.S. Geological Survey
Hydrologic Analysis Software Support Program
437 National Center
Reston, VA 20192
h2osoft@usgs.gov
Official versions of U.S. Geological Survey water-resources analysis
software are available for electronic retrieval via the World Wide
Web (WWW) at:
http://water.usgs.gov/software/
and via anonymous File Transfer Protocol (FTP) from:
water.usgs.gov (path: /pub/software).
The WWW page and anonymous FTP directory from which the CONTOUR
software can be retrieved are, respectively:
http://water.usgs.gov/software/contour.html
--and--
/pub/software/ground_water/contour
SEE ALSO
modflow(1) - Modular three-dimensional finite-difference
ground-water flow model
The URL for this page is: http://water.usgs.gov/cgi-bin/man_wrdapp?contour
Send questions or comments to h2osoft@usgs.gov