[OSM-dev] help with PostGIS and/or PostgreSQL queries?
# Background The Muddy Map Explorer will support text-based exploration and navigation of map data, making it accessible to blind and visually disabled users. The user interface will be patterned after MUDs (Multi-User Domain games), REPLs (Read, Eval, Print Loops), etc. It will let users explore a mapped area at various scales, getting descriptions of streets, amenities, etc. Using osm2pgsql, I've set up an exploratory database containing pretty much every possible relation and column, based on Geofabrik data on Texas and California (where my collaborator and I, respectively, live). So, I've got a nice pile of data to play with. However, I'm still a newbie at this, so I need help in developing some database queries. # Finding Nearby Ways Given a geographic location, it should be possible to find nearby ways, using only PostGIS and PostgreSQL. This would help us to get a working set of ways (and indirectly, nodes) for the user to explore. I found a few notions that seem tantalizingly close, but no exact matches: - Find nearest neighbours faster in PostGIS https://gis.stackexchange.com/questions/63667/find-nearest-neighbours-faster-in-postgis - How Do I Find The N Nearest Things To This Point In PostGis https://boundlessgeo.com/2011/09/indexed-nearest-neighbour-search-in-postgis - PostGIS / OSM: Faster query to find nearest line of points https://gis.stackexchange.com/questions/207592/postgis-osm-faster-query-to-find-nearest-line-of-points - Spatial Relationships and Measurements http://postgis.refractions.net/documentation/manual-svn/ST_DWithin.html Q: Is there an efficient way to find nearby ways for a location, using just PostgreSQL and/or PostGIS? # Tracking cities, etc. We'd like to be able to tell the user the current location, in human-friendly terms. Although we may know the starting location, traveling even a short distance could put the user into a different city, county, or country. We can't pester a geocoding service each time the user moves (and don't want to install and maintain Nominatim if we don't have to), so we need a local solution. A brute-force approach would be to look for nearby nodes that have TIGER (or equivalent) attributes. If the current location is "close enough" to a known address, that may be sufficient to our needs. Q: Is there an efficient way to get the administrative region for a location, using just PostgreSQL and/or PostGIS? -r -- http://www.cfcl.com/rdm Rich Morin r...@cfcl.com http://www.cfcl.com/rdm/resumeSan Bruno, CA, USA +1 650-873-7841 Software system design, development, and documentation ___ dev mailing list dev@openstreetmap.org https://lists.openstreetmap.org/listinfo/dev
[OSM-dev] looking for some spline code to adapt
I'm generating sets of tactile maps for a blind friend, as follows: OSM export files -(Ruby)-> PostScript -(lpr)-> swell paper I'm using straight lines for the roads, using the PostScript moveto and lineto operators. However, I'd like to use the curveto operator: x1 y1 x2 y2 x3 y3 curveto - This operator draws a curve from the current point to the point (x3, y3) using points (x1, y1) and (x2, y2) as control points. The curve is a Bézier cubic curve. In such a curve, the tangent of the curve at the current point will be a line segment running from the current point to (x1, y1) and the tangent at (x3, y3) is the line running from (x3, y3) to (x2, y2). -- http://www.tailrecursive.org/postscript/operators.html I'm not sure what the best starting point would be for this. I found this Perl code, but it seems a bit dated: http://wiki.openstreetmap.org/wiki/Osmarender/BezierCurves Clues, comments, and suggestions? -r -- http://www.cfcl.com/rdm Rich Morin r...@cfcl.com http://www.cfcl.com/rdm/resumeSan Bruno, CA, USA +1 650-873-7841 Software system design, development, and documentation ___ dev mailing list dev@openstreetmap.org https://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Application for Google Summer of Code 2016
FYI, the Elixir folks have set up a wiki page for back-up mentors: The following members of the Elixir community are willing and able to help with mentoring: -- https://github.com/elixir-lang/elixir/wiki/Mentors -r -- http://www.cfcl.com/rdm Rich Morin r...@cfcl.com http://www.cfcl.com/rdm/resumeSan Bruno, CA, USA +1 650-873-7841 Software system design, development, and documentation ___ dev mailing list dev@openstreetmap.org https://lists.openstreetmap.org/listinfo/dev
[OSM-dev] creating OSM-based tactile maps
I'm hoping for some suggestions on how to get from OpenStreetMap data to tactile maps for use by blind or visually impaired users. See below for a bit of background information and some qustions. -r Background I'm involved in a project to generate tactile maps for use by blind or visually impaired users. Currently, these are being fabricated by laser engraving from acrylic plastic, but I'm considering other options for reduced-cost duplication, etc. As an exploratory exercise, I used SketchUp's Pencil tool to trace some floor plans of a building, then used its 3D Fonts tool to add Braille annotations. I then exported a set of PDF files, imported them into Adobe Illustrator, and used them to drive the engraver. This produces reasonable results, but I'd like a more mechanized approach. I'd also like to take advantage of OSM's infrastructure and data, wherever appropriate. Ideally, I'd like to put together a mostly automated way to go from OSM's XML-based data format to engravable images. FWIW, I have skimmed a couple of books on OpenStreetMap: OpenStreetMap: Be your own Cartographer Bennett; Packt, 2010 OpenStreetMap: Using and Enhancing the Free Map of the World Ramm, Topf, and Chilton; UIT, 2011 However, as these books are a bit dated, the tools they mention (eg, Mapnik, Osmarender) may have been supplanted. So, I'm open to other suggestions! Questions What tool(s) would you suggest for: extracting all of the nodes (etc) within a polygon? rotating the map data (eg, to make a given street vertical)? rendering a map in PDF (eg, for use by Illustrator)? More generally, are web-based tools (eg, CSS, SVG, XSLT) still recommended as infrastructure for mechanically processing OSM data into rendered images? -- http://www.cfcl.com/rdm Rich Morin r...@cfcl.com http://www.cfcl.com/rdm/resumeSan Bruno, CA, USA +1 650-873-7841 Software system design, development, and documentation ___ dev mailing list dev@openstreetmap.org https://lists.openstreetmap.org/listinfo/dev
