Help me find corrupt Arcs (Sandra).

Help me find corrupt Arcs (Sandra).

Post by Jim Gaspar, P.E., F » Tue, 12 Dec 1995 04:00:00



I'm posting this for a co-worker who does not have news access.  Please
reply directly to her.

FROM:    Sandra Brown, GIS/CADD
 I'm working on a Geographic Information System (GIS) called GPG on an IBM
 system, and translating the data into an ARC/Info GIS system.  The IBM
 system stores arcs as three points, a beginning point, an arbitrary
 point on the arc, and an end point.  When the arcs are edited, GPG
 doesn't reset the original midpoint, therefore, occasionally the arc
 gets shortened so that the end point falls in "front" of the midpoint,
 making the arc coordinates corrupt.

 When this happens, the way ARC/Info translates it, the arc must reverse
 itself in order to pass thru the midpoint, creating large looping arcs.

 I'm trying to write an algorithm to test for this situation on the IBM
 side and throw the corrupt arcs out, but an not sure how to do this
 because basically all I have to work with that is valid is the start
 point and the end point.