Hi Monica, Both the ChangeDetector and the Matcher transformers are based on the MatchingFactory. It was divided into two transformers for their different purposes. The ChangeDetector is used to compare features by geometry and/or attributes, presumably one set of features is the control group and the other might have been modified somewhat. The output ports on the ChangeDetector are Unchanged, Added, and Deleted. That is, how the Revised compares to the Original, or which features will become updates in your database.
The ChangeDetector has a new unheralded parameter, "Lenient Geometry Matching". (Or in the MatchingFactory, it's LENIENT_GEOMETRY_MATCH no/yes.) The attached workspace demonstrates how it works. You can play with the options and try to detect change between the 3 created features which have the same vertices, but different direction or starting point. When LENIENT_GEOMETRY_MATCH is set to 'no', it will act as it did previously; features must have the same coordinates in the same order and direction to match. Now with LENIENT_GEOMETRY_MATCH set to 'yes', the order doesn't matter. The Matcher is for comparing two different datasets. It doesn't have the "Lenient Geometry Matching" parameter, but it does have "Interior Vertex Tolerance" and "Attribute(s) that must differ". A word of caution: geometry matching with the ChangeDetector or for end vertices with the Matcher is absolutely precise (despite the order). You may want to first run features through the CoordinateRounder. Happy FME'ing, ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Safe Software Inc. Dan Iseminger Surrey, BC, CANADA Product Specialist tel:604.501.9985.278 [EMAIL PROTECTED] fax:604.501.9965 http://www.safe.com ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > -----Original Message----- > From: monica marchetti [mailto:[EMAIL PROTECTED] > Sent: March 1, 2005 12:25 AM > To: [email protected] > Subject: [fme] Incremental update of geographic DB > > > Hi all, > > can anybody explain to me how ChageDetector works? Does it allow to > calculate an increment between two DB, and if so, how can it do it? Is > it by geometric matching, OID comparison or else? > > Thank you in advance for your help! > Cheers, > Monica Get the maximum benefit from your FME, FME Objects, or SpatialDirect via our Professional Services team. Visit www.safe.com/services for details. Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/fme/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
lenient_ChangeDetector.fmw
Description: lenient_ChangeDetector.fmw
