ZWISCHENPUNKTE
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Basic Information
Name of Program
ZWISCHENPUNKTE
VersionDate
January 1999
DescriptionDate
April 2008
Catchwords
splineinterpolation
contour line
topography
morphology
volume method
Short Description of Functionality
The program ZWISCHENPUNKTE generates topographical information by splineinterpolation. It can be used for a better interpretation of topographical data which is based on depth contours. Also its possible to generate depth information on a polygon to be used as a system boundary.
InputFiles
 inputfile (filetype zwischenpunkte.dat)
 file with depth contours (filetype insel.dat)
 (optional) file with profiles (filetype digi.gkk)
 (optional) file with a talwegpolygon (filetype digi.gkk)
 (optional) file with a system boundary polygon without depth information (filetype digi.gkk)
OutputFiles
 file with generated depth information (filetype geom.dat)
 (optional) file with points of intersection of depth contours and profiles (filetype geom.dat)
 (optional) file with depth points which define depth contours (filetype geom.dat)
 (optional) file with generated profiles (filetype digi.gkk)
 (optional) file with a system boundary polygon containing depth information (filetype insel.dat)
Methodology
The points of intersection between depth contours and profiles are found out. On each profile the points of intersection are used as fixed points for a spline interpolation. Depth information is generated by evaluating the splinefunctions between the depth contours. The evaluation is carried out at points which are located at constant distances on the profile and/or at a constant number of points which are centered equidistant between two depth contours. Profiles can be defined in an input file, or they will be generated by the program. The generation of profiles can be carried out either by generating profiles rightangled to a talwegpolygon (which is defined in an input file) or by generating profiles rightangled to the bank. The bank is defined as the contour line at MThw level (mean tidal highwater). Profiles which cross more than one channel are divided into new profiles (which don’t cross more than one channel). To avoid generation of not plausible depth data a smoothing routine is carried out after evaluating the splinefunctions. The smoothing is carried out, if the depth value of a generated point is not within the depth intervall of the closest depth contours that surround the neighbouring depth contours to the point. The smoothing is carried out by replacing the splinepoints by points of a second degree parable. The extrem value of the parable is defined by a smoothing parameter in the inputfile. Also its possible to suppress output of splinepoints which are out of a depth intervall surroundig the depth values of the neighbouring contour lines. Also its possible to suppress generation of splinepoints at profiles where the distance between at least two contour lines is greater than an maximum distance. The maximum depth intervall and the maximum distance must be defined in the input file. An extra function allows to evaluate depth information on an polygon which defines the system boundary. The depth information is found out by evaluating the intersection points of the polygon and the contour lines. It is also possible to generate depth information between the intersection points as described above. It it also possible to generate depth information by linear interpolation of the depth information at the intersection points. The depth information at the angles of the polygon is calculated by the mean value of the neighbouring intersection points.
Program(s) to run before this Program
Program(s) to run after this Program
ARCGIS, ArcGISApplications, MEDIANGLAETTUNG
Additional Information
Language
Fortran90
Additional software

Original Version
J. Fräßdorf
Maintenance
Documentation/Literature
$PROGHOME/examples/zwischenpunkte/*
see also Erzeugen von synthetischen Tiefenpunkten aus Isoliniendaten, published in Supercomputing News No. 4/1998 (available in German only).
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