Re: [postgis-users] Replicating ArcGIS relationship classes in PostGIS
The only item that immediately springs to mind would be creating views to preserve your join relationships. Any user that queried the view would automatically have that underlying joined information available. Perhaps you could explain more about the relationship classes you are trying to implement. On Thu, Oct 23, 2014 at 11:32 PM, Jochen Albrecht jochen.albre...@gmail.com wrote: I am working on behalf of a small non-profit that has so far used ArcGIS but is interested in moving open source. What kept them from making the move so far is that they are heavy users of relationship classes. The only discussion (inconclusive) that I could find was initiated by Lee Hachadoorian in 2008. Lots has changed since and I am wondering whether anybody has actually done this (implementing relationship classes in PostGIS). For example, back then, Lee suggested a trial-and-error approach to understand the encoding of relationship class tables. Have we gotten any further on this front? I am surprised that GIS Stack Exchange has no mentioning of this at all (assuming the search tools work). We are using relationship classes for 1:many and many:many relationships. This is not a problem for PostGIS; I just don't know how to migrate the geodatabase keeping those relationships intact. Cheers, Jochen ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
Re: [postgis-users] Replicating ArcGIS relationship classes in PostGIS
QGIS gets close to replicating the ArcGIS Functionality of relationships - but that is stored in the QGIS project and not the data (comparable to storing the relationship class in the mxd). I think views are the only way to do this in postgis. Randy On 10/24/2014 09:14 AM, David Haynes wrote: The only item that immediately springs to mind would be creating views to preserve your join relationships. Any user that queried the view would automatically have that underlying joined information available. Perhaps you could explain more about the relationship classes you are trying to implement. On Thu, Oct 23, 2014 at 11:32 PM, Jochen Albrecht jochen.albre...@gmail.com mailto:jochen.albre...@gmail.com wrote: I am working on behalf of a small non-profit that has so far used ArcGIS but is interested in moving open source. What kept them from making the move so far is that they are heavy users of relationship classes. The only discussion (inconclusive) that I could find was initiated by Lee Hachadoorian in 2008. Lots has changed since and I am wondering whether anybody has actually done this (implementing relationship classes in PostGIS). For example, back then, Lee suggested a trial-and-error approach to understand the encoding of relationship class tables. Have we gotten any further on this front? I am surprised that GIS Stack Exchange has no mentioning of this at all (assuming the search tools work). We are using relationship classes for 1:many and many:many relationships. This is not a problem for PostGIS; I just don't know how to migrate the geodatabase keeping those relationships intact. Cheers, Jochen ___ postgis-users mailing list postgis-users@lists.osgeo.org mailto:postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users -- - Randal Hale North River Geographic Systems, Inc http://www.northrivergeographic.com 423.653.3611 rjh...@northrivergeographic.com twitter:rjhale http://about.me/rjhale http://www.northrivergeographic.com/spatial-connect ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
Re: [postgis-users] Replicating ArcGIS relationship classes in PostGIS
If I recall correctly, you can export the tables that keep the relationships. If not, create a join and export only the two columns you need. For m:m relationships it's a bit nastier, and if you are using a enterprise geodatabase, with let's say, Oracle or SQL Server, you can query those, for sure. On Fri, Oct 24, 2014 at 11:17 AM, Randal Hale rjh...@northrivergeographic.com wrote: QGIS gets close to replicating the ArcGIS Functionality of relationships - but that is stored in the QGIS project and not the data (comparable to storing the relationship class in the mxd). I think views are the only way to do this in postgis. Randy On 10/24/2014 09:14 AM, David Haynes wrote: The only item that immediately springs to mind would be creating views to preserve your join relationships. Any user that queried the view would automatically have that underlying joined information available. Perhaps you could explain more about the relationship classes you are trying to implement. On Thu, Oct 23, 2014 at 11:32 PM, Jochen Albrecht jochen.albre...@gmail.com wrote: I am working on behalf of a small non-profit that has so far used ArcGIS but is interested in moving open source. What kept them from making the move so far is that they are heavy users of relationship classes. The only discussion (inconclusive) that I could find was initiated by Lee Hachadoorian in 2008. Lots has changed since and I am wondering whether anybody has actually done this (implementing relationship classes in PostGIS). For example, back then, Lee suggested a trial-and-error approach to understand the encoding of relationship class tables. Have we gotten any further on this front? I am surprised that GIS Stack Exchange has no mentioning of this at all (assuming the search tools work). We are using relationship classes for 1:many and many:many relationships. This is not a problem for PostGIS; I just don't know how to migrate the geodatabase keeping those relationships intact. Cheers, Jochen ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users ___ postgis-users mailing listpostgis-users@lists.osgeo.orghttp://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users -- - Randal Hale North River Geographic Systems, Inchttp://www.northrivergeographic.com423.653.3611 rjh...@northrivergeographic.com twitter:rjhale http://about.me/rjhalehttp://www.northrivergeographic.com/spatial-connect ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users -- George R. C. Silva SIGMA Consultoria http://www.consultoriasigma.com.br/ ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
Re: [postgis-users] Oriented BBox Efficient computing?
Ok if I understand right, implementing it at the sql level would be : - compute convex envelop - order edges by angle - round angle to a given precision, keep distinct values - for each angle, rotate and compute bbox and area keep bbox and rotation giving the min area. Cheers, Rémi-C 2014-10-23 18:46 GMT+02:00 Stephen V. Mather s...@clevelandmetroparks.com: That would be really cool. Could be a set of functions. It would be interesting to see if the triangulation optimizations listed at http://cgm.cs.mcgill.ca/~orm/rotcal.html are faster than the JTS/GEOS equivalents. Stephen V. Mather GIS Manager (216) 635-3243 (Work) clevelandmetroparks.com From: postgis-users-boun...@lists.osgeo.org postgis-users-boun...@lists.osgeo.org on behalf of Sandro Santilli s...@keybit.net Sent: Thursday, October 23, 2014 12:36 PM To: PostGIS Users Discussion Subject: Re: [postgis-users] Oriented BBox Efficient computing? On Thu, Oct 23, 2014 at 06:17:56PM +0200, Rémi Cura wrote: Wov thanks everybody : Seems it possible to do it fully geometrically : http://cgm.cs.mcgill.ca/~orm/rotcal.html Nice, would be a good candidate for a new PostGIS function (possibly via JTS/GEOS) --strk; () Free GIS Flash consultant/developer /\ http://strk.keybit.net/services.html ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
Re: [postgis-users] Oriented BBox Efficient computing?
As far as I can tell, you shouldn't order and rotate, or you'll be looking at a O(n^2) implementation. During an iteration of http://cgm.cs.mcgill.ca/~orm/rotcal.html, it seems like you can make the following assumptions: The next angle you should rotate to will be one of the four angles, given by the current extreme points and their next clockwise neighbour. So you should be able to find the next minimum clockwise rotation in O(1) time Also whenever you do a clockwise rotation to orient one of the support lines along a new edge, the extreme points for the other support lines stay the same. You only need to update the extreme point that was on the edge we now use as a support line, to its next clockwise point. Using the new extreme points and caliper's angle, you can calculate the bbox area in O(1) time as well. Regards Åsmund On Fri, Oct 24, 2014 at 7:09 PM, Rémi Cura remi.c...@gmail.com wrote: Ok if I understand right, implementing it at the sql level would be : - compute convex envelop - order edges by angle - round angle to a given precision, keep distinct values - for each angle, rotate and compute bbox and area keep bbox and rotation giving the min area. Cheers, Rémi-C 2014-10-23 18:46 GMT+02:00 Stephen V. Mather s...@clevelandmetroparks.com : That would be really cool. Could be a set of functions. It would be interesting to see if the triangulation optimizations listed at http://cgm.cs.mcgill.ca/~orm/rotcal.html are faster than the JTS/GEOS equivalents. Stephen V. Mather GIS Manager (216) 635-3243 (Work) clevelandmetroparks.com From: postgis-users-boun...@lists.osgeo.org postgis-users-boun...@lists.osgeo.org on behalf of Sandro Santilli s...@keybit.net Sent: Thursday, October 23, 2014 12:36 PM To: PostGIS Users Discussion Subject: Re: [postgis-users] Oriented BBox Efficient computing? On Thu, Oct 23, 2014 at 06:17:56PM +0200, Rémi Cura wrote: Wov thanks everybody : Seems it possible to do it fully geometrically : http://cgm.cs.mcgill.ca/~orm/rotcal.html Nice, would be a good candidate for a new PostGIS function (possibly via JTS/GEOS) --strk; () Free GIS Flash consultant/developer /\ http://strk.keybit.net/services.html ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users ___ postgis-users mailing list postgis-users@lists.osgeo.org http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
