[Talk-us] MassGIS Building Import - simplify
Hi, I would like to continue the discussion on the simplification of the MassGIS buildings in a new thread. In my town, there are 5427 buildings. 43,628 nodes, or 8 nodes per structure. I did a 0.25 meter simplify on the entire town, and the node count went down to 41,809. We are looking at an excess of 5%. 0.25 meter may seem tight, but consider that source data was from 30cm and 15cm per pixel, and I am sure the algorithms used do some kind of sub pixel interpolation. Until I can figure out how to do the simplification from my scripts, we will add instructions on the wiki on how to do a 0.25 meter simply on the source layer in JOSM first. Thanks Jason ___ Talk-us mailing list Talk-us@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] MassGIS Building Import - simplify
Does anyone have a good definition of overnoding for the purposes of OSM? Is it just whatever the algorithms for simplify line simplify way say is good with default parameters say? Thanks, Jeff On Thu, Dec 13, 2012 at 5:12 PM, Jason Remillard remillard.ja...@gmail.comwrote: Hi, I would like to continue the discussion on the simplification of the MassGIS buildings in a new thread. In my town, there are 5427 buildings. 43,628 nodes, or 8 nodes per structure. I did a 0.25 meter simplify on the entire town, and the node count went down to 41,809. We are looking at an excess of 5%. 0.25 meter may seem tight, but consider that source data was from 30cm and 15cm per pixel, and I am sure the algorithms used do some kind of sub pixel interpolation. Until I can figure out how to do the simplification from my scripts, we will add instructions on the wiki on how to do a 0.25 meter simply on the source layer in JOSM first. Thanks Jason ___ Talk-us mailing list Talk-us@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-us -- Jeff Meyer Global World History Atlas www.gwhat.org j...@gwhat.org 206-676-2347 ___ Talk-us mailing list Talk-us@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] MassGIS Building Import - simplify
Hi, On 14 December 2012 02:12, Jason Remillard remillard.ja...@gmail.com wrote: In my town, there are 5427 buildings. 43,628 nodes, or 8 nodes per structure. I did a 0.25 meter simplify on the entire town, and the node count went down to 41,809. We are looking at an excess of 5%. 0.25 meter may seem tight, but consider that source data was from 30cm and 15cm per pixel, and I am sure the algorithms used do some kind of sub pixel interpolation. Until I can figure out how to do the simplification from my scripts, .. As I understand some processing is done in PostGIS already. You could add a ST_SimplifyPreserveTopology(the_geom, 0.25) at the end of the process and it should have the same effect. Cheers ___ Talk-us mailing list Talk-us@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] MassGIS Building Import - simplify
Hi, The ST_SimplifyPreserveTopology worked great! I will upload new data tomorrow. Thanks Jason. On Thu, Dec 13, 2012 at 9:18 PM, andrzej zaborowski balr...@gmail.comwrote: Hi, On 14 December 2012 02:12, Jason Remillard remillard.ja...@gmail.com wrote: In my town, there are 5427 buildings. 43,628 nodes, or 8 nodes per structure. I did a 0.25 meter simplify on the entire town, and the node count went down to 41,809. We are looking at an excess of 5%. 0.25 meter may seem tight, but consider that source data was from 30cm and 15cm per pixel, and I am sure the algorithms used do some kind of sub pixel interpolation. Until I can figure out how to do the simplification from my scripts, .. As I understand some processing is done in PostGIS already. You could add a ST_SimplifyPreserveTopology(the_geom, 0.25) at the end of the process and it should have the same effect. Cheers ___ Talk-us mailing list Talk-us@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-us
