Re: [postgis-users] Reducing the number of points in a GPS track
Hi Alexandre, perhaps you could run ST_Simplify in a function with a while loop testing over ST_NPoints: CREATE OR REPLACE FUNCTION simplify_npoints(geometry, integer) RETURNS geometry AS $BODY$ DECLARE InGeom alias for $1; maxpoints alias for $2; npoints integer; tolerance float; outGeom geometry; Begin npoints:=ST_NPoints(InGeom); outGeom:=InGeom; tolerance:=0.0; while npoints maxpoints loop tolerance:=tolerance + 0.001; outGeom:=ST_Simplify(InGeom, tolerance); npoints:=ST_NPoints(outGeom); end loop; return outGeom; End; $BODY$ LANGUAGE plpgsql VOLATILE COST 100; ALTER FUNCTION simplify_npoints(geometry, integer) OWNER TO postgres; I don't know if it will work (didn't test). And perhaps bigger iteration steps would be sufficient, too... Good luck! Regards, Birgit. Am 24.10.2012 14:29, schrieb Alexandre Saunier: Hello. I would like to know if some tools are available in PostGIS to simplify a linestring to a given maximum number of points. A bit like the simplify,count=... filter in GPSBabel: http://www.gpsbabel.org/htmldoc-development/filter_simplify.html ST_Simplify is close to what I need but I don't know in advance what tolerance to use, only the final maximal number of points. Is there a way to do that kind of simplification with PostGIS? Thanks! Alexandre ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
[postgis-users] out of memory error : String too long for converting encoding
i have 4 GB RAM WINDOWS XP 64-bit shared_buffer:512 MB checkpoint_segment 32 work_mem;5MB i wish to import 540 MB tif image into database postgis 2.0 . without tile . i got success test.sql file. but error occured when psql -d dbname -f test.sql error : String is 978678801 byte too long for encoding conversion pls give any suitable solution with thanks mahavir ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
[postgis-users] out of memory
i have 4 GB RAM WINDOWS XP 64-bit shared_buffer:512 MB checkpoint_segment 32 work_mem;5MB i wish to import 540 MB tif image into database postgis 2.0 . without tile . i got success test.sql file. but error occured when psql -d dbname -f test.sql error : String is 978678801 byte too long for encoding conversion pls give any suitable solution with thanks mahavir ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
[postgis-users] Finding extra points
Greetings.. Is there a function or combination of functions in postGIS-2 that will help calculate points in between 2 given. I have imported a point shape file containing the National Hurricane Center's Watch/Warning breakpoints when they issue the warnings it contains at least 2 locations from this shape file. is there a way to calculate what points from the shape file would be in between the 2 given?? -- *Jeff Lake* MichiganWxSystem http://www.michiganwxsystem.com AllisonHouse http://www.allisonhouse.com GRLevelXStuff http://www.grlevelxstuff.com ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
Re: [postgis-users] Finding extra points
On Thu, Oct 25, 2012 at 07:15:20AM -0400, Jeff Lake wrote: Greetings.. Is there a function or combination of functions in postGIS-2 that will help calculate points in between 2 given. I have imported a point shape file containing the National Hurricane Center's Watch/Warning breakpoints when they issue the warnings it contains at least 2 locations from this shape file. is there a way to calculate what points from the shape file would be in between the 2 given?? You could draw a line between the two points and find the points which are within a given distance from them. See ST_MakeLine and ST_DWithin. --strk; http://www.cartodb.com - Map, analyze and build applications with your data ~~ http://strk.keybit.net ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
Re: [postgis-users] Reducing the number of points in a GPS track
On Oct 24, 2012, at 2:29 PM, Alexandre Saunier wrote: Hi Alex, A bit like the simplify,count=... filter in GPSBabel: http://www.gpsbabel.org/htmldoc-development/filter_simplify.html Is there a way to do that kind of simplification with PostGIS? A way could be to : - Compute length of your road with ST_Length - Use ST_Line_Interpolate_Point to compute each point on your line - Aggregate all points computed in a new simplified line with ST_MakeLine HTH, O. ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
Re: [postgis-users] out of memory
You may want to increase your shared_buffer to 25% of your system's available memory. You really should tile your raster. -bborie On 10/25/2012 02:19 AM, Mahavir Trivedi wrote: i have 4 GB RAM WINDOWS XP 64-bit shared_buffer:512 MB checkpoint_segment 32 work_mem;5MB i wish to import 540 MB tif image into database postgis 2.0 . without tile . i got success test.sql file. but error occured when psql -d dbname -f test.sql error : String is 978678801 byte too long for encoding conversion pls give any suitable solution with thanks mahavir ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users -- Bborie Park Programmer Center for Vectorborne Diseases UC Davis 530-752-8380 bkp...@ucdavis.edu ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
Re: [postgis-users] Pg_wrapper error
You're probably going to want to call raster2pgsql directly instead of pg_wrapper. If the problem is with pg_wrapper, you're better asking a debian mailing list. So... /usr/bin/raster2pgsql MYRASTER MYTABLE | psql -d MYDB -bborie On 10/25/2012 08:26 AM, José Pedro Santos wrote: Dear all, I have one problem when I try to load raster to Postgis with the script raster2pgsql from the shell. I have this error: Error: pg_wrapper: invalid command name Before this error (I have Postgis version 2.0) I can't use the command (raster2pgsql) in the shell (was not found) but i enable it with this expression: sudo ln -sf /usr/share/postgresql-common/pg_wrapper /usr/bin/raster2pgsql After that the error about pg_wrapper appear. Any suggestion? Best Regards and thanks, Jose Santos ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users -- Bborie Park Programmer Center for Vectorborne Diseases UC Davis 530-752-8380 bkp...@ucdavis.edu ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
[postgis-users] How to eliminate small gaps produced by ST_union?
I'm trying to Aggregate\Dissolve a set of adjacent, but not touching polygons in Postgis. The geometries were created editing the Postgis table in QGIS created, with snapping and avoid overlap in the layer. I used ST_Union like this: SELECT ST_Union(the_geom) FROM table; Small gaps similar to lines appear in the result. This happens when the adjacent polygons do not share the exact same vertices. [image: Inline image 2] Is there a way to eliminate this gaps or small angles within Postgis? I know that v.clean in GRASS can eliminate small angles, and correct topology, but that would mean I needed to copy the features to GRASS, correct them and copy it back to Postgis. Thanks in advance, Alexandre Neto image.jpeg___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
Re: [postgis-users] How to eliminate small gaps produced by ST_union?
You may try to construct a topology within PostGIS-2.0, using a small tolerance, and then get the geometries back. --strk; On Thu, Oct 25, 2012 at 05:54:05PM +0100, Alexandre Neto wrote: I'm trying to Aggregate\Dissolve a set of adjacent, but not touching polygons in Postgis. The geometries were created editing the Postgis table in QGIS created, with snapping and avoid overlap in the layer. I used ST_Union like this: SELECT ST_Union(the_geom) FROM table; Small gaps similar to lines appear in the result. This happens when the adjacent polygons do not share the exact same vertices. [image: Inline image 2] Is there a way to eliminate this gaps or small angles within Postgis? I know that v.clean in GRASS can eliminate small angles, and correct topology, but that would mean I needed to copy the features to GRASS, correct them and copy it back to Postgis. Thanks in advance, Alexandre Neto ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
Re: [postgis-users] How to eliminate small gaps produced by ST_union?
My impression is that working topologies is slow, especially with large datasets - lots of computation involved. How effective would this be with hundreds of thousands or millions or small polygons? Just running ST_Union() takes hours to days. Thanks Brent Wood --- On Fri, 10/26/12, Sandro Santilli s...@keybit.net wrote: From: Sandro Santilli s...@keybit.net Subject: Re: [postgis-users] How to eliminate small gaps produced by ST_union? To: PostGIS Users Discussion postgis-users@postgis.refractions.net Date: Friday, October 26, 2012, 6:04 AM You may try to construct a topology within PostGIS-2.0, using a small tolerance, and then get the geometries back. --strk; On Thu, Oct 25, 2012 at 05:54:05PM +0100, Alexandre Neto wrote: I'm trying to Aggregate\Dissolve a set of adjacent, but not touching polygons in Postgis. The geometries were created editing the Postgis table in QGIS created, with snapping and avoid overlap in the layer. I used ST_Union like this: SELECT ST_Union(the_geom) FROM table; Small gaps similar to lines appear in the result. This happens when the adjacent polygons do not share the exact same vertices. [image: Inline image 2] Is there a way to eliminate this gaps or small angles within Postgis? I know that v.clean in GRASS can eliminate small angles, and correct topology, but that would mean I needed to copy the features to GRASS, correct them and copy it back to Postgis. Thanks in advance, Alexandre Neto ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
Re: [postgis-users] How to eliminate small gaps produced by ST_union?
Try to use function st_cleanpolygon or st_buffer with a radius of 0.0. Regards Bo Victor Thomsen Aestas-GIS Denmark Den 25-10-2012 18:54, Alexandre Neto skrev: I'm trying toAggregate\Dissolve a set of adjacent, but not touching polygons in Postgis.The geometries were created editing the Postgis table in QGIS created, with snapping and avoid overlap in the layer. I usedST_Union like this: SELECT ST_Union(the_geom) FROM table; Small gaps similar to lines appear in the result. This happens when the adjacent polygons do not share the exact same vertices. Is there a way to eliminate this "gaps" or "small angles" within Postgis? I know that v.clean in GRASS can eliminate small angles, and correct topology, but that would mean I needed to copy the features to GRASS, correct them and copy it back to Postgis. Thanks in advance, Alexandre Neto ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
Re: [postgis-users] How to eliminate small gaps produced by ST_union?
If you don't mind altering your other edges somewhat in the process, dilate/erode will blow those away, http://blog.opengeo.org/2010/11/22/removing-complexities/ P. On Thu, Oct 25, 2012 at 10:44 AM, Bo Victor Thomsen bo.victor.thom...@gmail.com wrote: Try to use function st_cleanpolygon or st_buffer with a radius of 0.0. Regards Bo Victor Thomsen Aestas-GIS Denmark Den 25-10-2012 18:54, Alexandre Neto skrev: I'm trying to Aggregate\Dissolve a set of adjacent, but not touching polygons in Postgis. The geometries were created editing the Postgis table in QGIS created, with snapping and avoid overlap in the layer. I used ST_Union like this: SELECT ST_Union(the_geom) FROM table; Small gaps similar to lines appear in the result. This happens when the adjacent polygons do not share the exact same vertices. Is there a way to eliminate this gaps or small angles within Postgis? I know that v.clean in GRASS can eliminate small angles, and correct topology, but that would mean I needed to copy the features to GRASS, correct them and copy it back to Postgis. Thanks in advance, Alexandre Neto ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
Re: [postgis-users] Finding extra points
Sure, use linear referencing functions[1] to interpolate along a line between the two input points. For example, to find 10 points in-between 'POINT(2 8)' and 'POINT(3 5)': select ST_AsText(ST_Line_Interpolate_Point(ST_MakeLine(ST_MakePoint(2, 8), ST_MakePoint(3, 5)), f::float/10)) from generate_series(0,10) as f; Also, if you have a Z or M coordinate to also interpolate, you can add it as the third and fourth argument of ST_MakeLine, and you will see the interpolated result. These extra coordinate dimensions, for example, could be an attribute quantity from your source point data. Keep in mind, these are linear interpolation techniques. -Mike [1] http://postgis.refractions.net/documentation/manual-2.0/reference.html#Linear_Referencing On 26 October 2012 00:15, Jeff Lake j...@michiganwxsystem.com wrote: Greetings.. Is there a function or combination of functions in postGIS-2 that will help calculate points in between 2 given. I have imported a point shape file containing the National Hurricane Center's Watch/Warning breakpoints when they issue the warnings it contains at least 2 locations from this shape file. is there a way to calculate what points from the shape file would be in between the 2 given?? -- Jeff Lake MichiganWxSystem AllisonHouse GRLevelXStuff ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
[postgis-users] PostgreSQL HStore and PostGIS
Hello, I have a need to design and develop an application which handles a wide variety of possible variations for a database schema. I am looking into a number of options including popular NoSQL databases. I do keep coming back to PostgreSQL and PostGIS since I need to deal with geometries in a more complex manner than either MongoDB or CouchDB Geospatial Indexing offer. With that said, I have been looking into the new capabilities available with PostgreSQL HStore modulehttps://postgres.heroku.com/blog/past/2012/3/14/introducing_keyvalue_data_storage_in_heroku_postgres/ as a possible alternative to be able to store geometries with PostGIS and tie additional key/value pairs in a hstore data type column. - Can anyone comment on successful or unsuccessful attempts to implement such a technology approach integrating PostGIS with HStore? - How would one extract data out in such a manner (I suspect a custom program would need to be run)? I do realize HStore is very new on the scene, but curious if this environment is something that will even work with PostGIS. Thanks! Cheers, Blair ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
Re: [postgis-users] PostgreSQL HStore and PostGIS
Blair, * Blair Deaver (blairdea...@gmail.com) wrote: With that said, I have been looking into the new capabilities available with PostgreSQL HStore Uhm.. hstore isn't exactly new. It's been around since something like 8.0.. It is amusing how people are just now coming to see. :) - Can anyone comment on successful or unsuccessful attempts to implement such a technology approach integrating PostGIS with HStore? I've not heard of anyone putting geometries into hstore's. It'd be possible, but realize that to put something into an hstore, it has to be text. Also, I don't think you'd be able to create a geometry index over geometries which are inside of an hstore.. Or at least, if you did, it might be difficult to actually use. - How would one extract data out in such a manner (I suspect a custom program would need to be run)? Not sure what you mean by this, but you'd need to query the hstore using the key that you want and then pull the geometry out as text and cast it to an actual geometry column to use it. If you just want the data out in a text format, you'd run asewkt() on the geometry after you pull it out of the hstore. Thanks, Stephen signature.asc Description: Digital signature ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
Re: [postgis-users] out of memory
hi i split the image (tiff) into 100 X 100 tile .(RASTER IMAGE 500 MB input ) but problem occurred when i export it then output size increase. (image input size = 1591 X 1446) (image output size = 1600 X 1450) can i change blocksize of server ? if yes then how ? my system XP Windows 64-bit 4 GB RAM thanks mahavir ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
