Re: [Q] geodetic spatial functions

Kiyoung, It looks like the altitude is not taken into account, but that distance is measured only along the datum ellipsoid (geodesic). Look at page 1-12 (34) of the pdf document "Informix Geodetic DataBlade Module User's Guide" at http://www-3.ibm.com/software/data/informix/pubs/library/interim/8675-pdf.html -Ken Kiyoung Yang wrote: > Hi, > > I'm using Informix 9.30 with geodetic datablade (3.00). It seems > that the geodetic spatial functions, e.g., distance, doesn't > take the 3rd element of a point into account. The following > is the script I tried with the result. > > create table test (location GeoObject);> > insert into test values ('GeoPoint((3,4,10),ANY,ANY)'); > insert into test values ('GeoPoint((3,5,1),ANY,ANY)');> > CREATE INDEX test_idx > ON test (location geospcalt_ops) > USING RTREE ;> > select location, distance(location, '((3,4,0),ANY, ANY)'::GeoPoint) from> test; > > ## RESULT > > location GeoPoint((3,4,10),ANY,ANY) > (expression) 0.00 > > location GeoPoint((3,5,1),ANY,ANY) > (expression) 111167.9466418 > > If the 3rd element is considered, the distance between (3,4,0) and (3,5,1) > should be closer than that between (3,4,0) and (3,4,10), but it seems that > this is not the case for geodetic distance function. I'm wondering if this > is true that the geodetic spatial functions doesn't consider the 3rd > element in the point or if there is something that I'm missing here. > > Any comments would be appreciated. > > Thanks in advance, > Kiyoung.. > >

Ken, Thanks for the clarification. I'm wondering, then, if there is any other function that take the altitude into account when computing the distance. Do we have to implement this ourselves? Any comments would be appreciated. Thanks in advance, Kiyoung.. On Tue, 28 Oct 2003, Ken Tanaka wrote: > Kiyoung, > > It looks like the altitude is not taken into account, but that distance > is measured only along the datum ellipsoid (geodesic). Look at page 1-12 > (34) of the pdf document "Informix Geodetic DataBlade Module User's > Guide" at > > http://www-3.ibm.com/software/data/informix/pubs/library/interim/8675-pdf.html > > -Ken > > Kiyoung Yang wrote: > > Hi, > > > > I'm using Informix 9.30 with geodetic datablade (3.00). It seems > > that the geodetic spatial functions, e.g., distance, doesn't > > take the 3rd element of a point into account. The following > > is the script I tried with the result. > > > > create table test (location GeoObject);> > > > insert into test values ('GeoPoint((3,4,10),ANY,ANY)'); > > insert into test values ('GeoPoint((3,5,1),ANY,ANY)');> > > > CREATE INDEX test_idx > > ON test (location geospcalt_ops) > > USING RTREE ;> > > > select location, distance(location, '((3,4,0),ANY, ANY)'::GeoPoint) from> > test; > > > > ## RESULT > > > > location GeoPoint((3,4,10),ANY,ANY) > > (expression) 0.00 > > > > location GeoPoint((3,5,1),ANY,ANY) > > (expression) 111167.9466418 > > > > If the 3rd element is considered, the distance between (3,4,0) and (3,5,1) > > should be closer than that between (3,4,0) and (3,4,10), but it seems that > > this is not the case for geodetic distance function. I'm wondering if this > > is true that the geodetic spatial functions doesn't consider the 3rd > > element in the point or if there is something that I'm missing here. > > > > Any comments would be appreciated. > > > > Thanks in advance, > > Kiyoung.. > > > > > >