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/* COMMANDS FOR PREPROCESSING YOUR COVERAGES FOR TIN CREATION
/* PURPOSE: This procedure will help you in creating a Triagulated
/* Irregular Network from a given point coverage, using a column
/* from the .pat as the z value (i.e. the value from which interpolation
/* will be done). In addition, this process will use a polygon
/* coverage of your study area as a boundary, or breakline, for the
/* TIN creation. As a result, the TIN will not be extrapolated over or
/* beyond the boundary. IMPORTANT NOTE: ALL COVERAGES MUST BE
/* PROJECTED BEFORE THIS PROCEDURE IS RUN!
/*
/* PREPROCESSING STEPS
/*
/* INPUT NEEDED:
/* Coverages:
/* pointcov -- a point coverage from
/* which the TIN will be created (for help in creating the point
/* coverage, see the AML entitled, Point Coverage Creation .)
/* boundary -- a polygon coverage of your study area
/* Text Files:
/* measurement.dat -- a file containing the
/* pointcov-id and corresponding measurement, or z value for
/* each station in the point coverage
/* dummy.dat -- a file containing the boundary-id and
/* corresponding z value for each polygon in
/* your polygon coverage. If you do not know the z value for the
/* boundary, the z value column (called spot) must contain the NO
/* DATA value for each polygon (-9999).
/* Be sure to type "end" and hit return at the end of
/* each text file before saving it.
/* Now you are ready to add these columns to the respective .pats.
/* Arc: Tables
/* Enter Command: define zvalue.dat [Defines a new table called zvalue.dat]
/* Item Name: pointcov-id [Defines the columns in your table]
/* Item Width: 10 [NOTE: your item width may vary!]
/* Item Output Width: 10
/* Item Type: i
/* Item Name: msrmnt
/* Item Width: 8
/* Item Output Width: 8
/* Item Type: N [Defines "msrmnt" as a real number with
/* 4 digits after the decimal point; depending on the
/* Item Decimal Places: 4 values, your input at this point may vary]
/* Item Name:
/* Enter Command: add from measurement.dat [Adds the data from your
/* text file into zvalue.dat]
/* Enter Command: q
/* Arc: joinitem zvalue.dat pointcov.pat pointcov.pat pointcov-id
/* pointcov-id [joins the new table with the pat]
/* Now, the same procedure must be done for the polygon coverage.
/* Arc: Tables
/* Enter Commmand: define poly.dat
/* Item Name: boundary-id
/* Item Width: 10 [NOTE: your item width may vary!]
/* Item Output Width: 10
/* Item Type: i
/* Item Name: spot
/* Item Width: 8 [NOTE: item width and type may vary!]
/* Item Output Width: 8
/* Item Type: i
/* Item Name:
/* Enter Command: add from dummy.dat [Adds the data from your text
/* file into zvalue.dat]
/* Enter Command: q
/* Arc: joinitem poly.dat boundary.pat boundary.pat boundary-id boundary-id
/* [joins the new table with the pat]
/**********************************************************************
/* AN ARC AML FOR TIN CREATION, USING A POLYGON COVERAGE AS A
/* HARDCLIP FOR BREAKLINES
/*
/* AML NAME: tin.aml
/*
/* FUNCTION: Creates a TIN called tinbound with a given point coverage,
/* using desired z values for interpolation. Also uses a
/* polygon coverage of the study area to establish a breakline for the
/* TIN
/*
/* INPUTS:
/* pointcov -- a projected point coverage from which the
/* TIN will be created. Within the .pat of this coverage, the desired
/* z values have been added under a column called "msrmnt"
/* boundary -- a projected polygon coverage of your study
/* area. Within the .pat of this coverage, the desired z values
/* have been added for each polygon, under a column called "spot".
/* If the z values for the polygons are not known then NO DATA values
/* (-9999) should be added, instead.
************************************************************************
/* invoke Arc's CREATETIN program
createtin tinbound
/* declare the polygon coverage a hardclip polygon and use the
/* column, "spot" as the z values
cover boundary poly spot hardclip # #
/* declare the point coverage for the TIN interpolation and use
the column "msrmnt" as the z values
cover pointcov point msrmnt # # #
end
/* describe the TIN to double check results
describetin tinbound
/* view the TIN in Arcplot
arcplot
display 9999
tin tinbound
quit
/* quit the AML
&return
***********************************************************************
/* SPECIAL NOTE: If you find that your TIN has long, skinny triangles,
/* it may be necessary to set weed tolerance on the TIN. A
/* weed tolerance "skips over" nodes within a desired distance,
/* so that the triangles will be more accurate. The default weed
/* tolerance /*is 1/1000 of the xmax-xmin or ymax-ymin, whichever
/* is greater. To set the weed tolerance, type, for example:
/*
/* Arc: createtin tinbound 5000.00
/* This creates a weed tolerance of 5000.00 units (whatever your
/* distance units are for the projection)
************************************************************************