Re: [OSM-dev] Zeroing or Extending a Hillshade-Tiff
On Tue, Mar 12, 2013 at 07:00:25PM +0100, Peter Körner wrote: Am 11.03.2013 21:10, schrieb Sven Geggus: Peter Körner osm-li...@mazdermind.de wrote: what way would you choose and wich tools could be used to go that way? Use the Water-Polygons from openstreetmapdata.com instead of land polygons. That's not that easy for the polar regions, because transforming the splittet polygons to the destination projection results in gaps because of straigt lines not beeing curved. For the land there are complete polygons which are used on the Antarctica map but there are no complete water polygons, because they would be too complex (a huge polygon with 400.000+ holes). So in order to get this right one would need to modify jochend osmcoastline tool to support EPSG:3031 natively, to all corrdinates are transformed before splitting and calculating the water polygons. Another option would be to split up the long straight lines resulting from the splitting into shorter pieces. If the pieces are short enough, it should be okay. Maybe there is some tool around that can do that easily? I don't want to put more and more of these things into OSMCoastline, because they are not really related to coastlines, but general issues with large objects. My first plan was to have a separate tool for the splitting, but because I needed the split land polygons to create the water polygons I decided to add this functionality into OSMCoastline to make it not too complicated to use for the most common cases. Jochen -- Jochen Topf joc...@remote.org http://www.remote.org/jochen/ +49-721-388298 ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Zeroing or Extending a Hillshade-Tiff
On Wed, Mar 13, 2013 at 12:13 PM, Jochen Topf joc...@remote.org wrote: On Tue, Mar 12, 2013 at 07:00:25PM +0100, Peter Körner wrote: That's not that easy for the polar regions, because transforming the splittet polygons to the destination projection results in gaps because of straigt lines not beeing curved. For the land there are complete polygons which are used on the Antarctica map but there are no complete water polygons, because they would be too complex (a huge polygon with 400.000+ holes). So in order to get this right one would need to modify jochend osmcoastline tool to support EPSG:3031 natively, to all corrdinates are transformed before splitting and calculating the water polygons. Another option would be to split up the long straight lines resulting from the splitting into shorter pieces. If the pieces are short enough, it should be okay. Maybe there is some tool around that can do that easily? I don't want to put more and more of these things into OSMCoastline, because they are not really related to coastlines, but general issues with large objects. I have done this in the past with the split land and water shapefiles to work with polar projections. ogr2ogr's -segmentize option with a value of 0.1 worked well for me on the WGS84 files. -- AJ Ashton ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Zeroing or Extending a Hillshade-Tiff
On Wednesday 13 March 2013, Jochen Topf wrote: Another option would be to split up the long straight lines resulting from the splitting into shorter pieces. If the pieces are short enough, it should be okay. Maybe there is some tool around that can do that easily? I don't want to put more and more of these things into OSMCoastline, because they are not really related to coastlines, but general issues with large objects. Not quite actually - in case of splitting the problem does not stem from the long segments but from the fact that you split one polygon but do not split the edge of the adjacent one at the same time. If you'd do that the edges could have any length, they would still fit after the reprojection (although you could get intersections between the actual coastline and the splitting lines). -- Christoph Hormann http://www.imagico.de/ ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Zeroing or Extending a Hillshade-Tiff
Am 11.03.2013 21:10, schrieb Sven Geggus: Peter Körner osm-li...@mazdermind.de wrote: what way would you choose and wich tools could be used to go that way? Use the Water-Polygons from openstreetmapdata.com instead of land polygons. That's not that easy for the polar regions, because transforming the splittet polygons to the destination projection results in gaps because of straigt lines not beeing curved. For the land there are complete polygons which are used on the Antarctica map but there are no complete water polygons, because they would be too complex (a huge polygon with 400.000+ holes). So in order to get this right one would need to modify jochend osmcoastline tool to support EPSG:3031 natively, to all corrdinates are transformed before splitting and calculating the water polygons. Peter ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Zeroing or Extending a Hillshade-Tiff
Peter Körner osm-li...@mazdermind.de wrote: what way would you choose and wich tools could be used to go that way? Use the Water-Polygons from openstreetmapdata.com instead of land polygons. This way you can use a layer order like this: * gray background * hillshade * water polygons without opacity Regards Sven -- In my opinion MS is a lot better at making money than it is at making good operating systems (Linus Torvalds, August 1997) /me is giggls@ircnet, http://sven.gegg.us/ on the Web ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
[OSM-dev] Zeroing or Extending a Hillshade-Tiff
Hi I have a Hillshading-Tiffs (a GeoTIFF with a single Greyscale-Band) in the correct projection and correctly aligned. My problem is, that it's slightly smaller then the area I'd like to render using mapnik: http://imageshack.us/photo/my-images/202/bildschirmfotovom201303.png/ There are options i'm aware of: a) set the water level (its values 180-182 in the greyscale-band) to transparent, so there's no visible border at the end of the image b) extend the image with value 181 at the borders to fit the size of the image i'm going to render My question is: what way would you choose and wich tools could be used to go that way? Regards, Peter ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
Re: [OSM-dev] Zeroing or Extending a Hillshade-Tiff
On Thursday 07 March 2013, Peter Körner wrote: b) extend the image with value 181 at the borders to fit the size of the image i'm going to render My question is: what way would you choose and wich tools could be used to go that way? for b: gdalwarp -dstnodata 181 Note it is usually best to only hillshade the land and not the water so if you draw the water above the hillshade you won't have this edge problem (it is of course even better to modify the DEM before shading to match the coastline but that's quite a bit more complex). I am currently preparing rendering polar maps myself so if you need hillshade images for the lower zoom levels i could provide them - for zoom=2 with 6000km map area (i think that's what you are using as well): http://www.imagico.de/files/gshade_2_0_0.tif.bz2 Greetings, -- Christoph Hormann http://www.imagico.de/ ___ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
