Richard Weait wrote: > On Fri, Mar 12, 2010 at 1:02 PM, Vangelis Katsikaros <[email protected]> wrote: > >> Hi again, well I had made a mistake. I though that the SVG output of OSM >> kept the coordinates of the map points the same in the SVG (that the 0 >> of Greenwich, was also the x=0 in the SVG). But, I though wrong :) > > Dear Vangelis, > > No problem. There are many ways to use OSM. Finding the "right" way > depends on what you want to do, and eventually depends on how you like > to do things. Let's look at your requirements in a little more > detail. > > You want to look at a substantial portion of the northern hemisphere. > You want to show mostly plain coastlines > You want to "overlay some GPS points" > You want SVG output that you can manipulate in inkscape. > > Tell us more about the GPS points. > Are these points already objects in the OSM database? > Could they be added to the OSM database? > Are these points or collections of points in the form of tracks? > Is there only one set of points and tracks or do they change at times? > How often will you make a new map?
Hello Richard Yes, these are indeed the requirements. The data I will overlay extend to the seas around Greenland, Scandinavia and some N Atlantic. I also want to see only coastlines and the land as a fill (like the Wikimedia Commons gray maps). The points are not in the OSM database. The GPS points are tracks of ships (so I guess that they aren't of any interest to OSM). I converted them from AIS data, but converting to the proper format isn't a problem, since I can handle perl quite well (text based transformations are not an issue). So, I have a list of points (right now it doesn't matter if they come from different objects) and the coordinates are from GPS data. I have converted that in the proper SVG <path>, so that when I put this <path> in the SVG with the map, it will be overlayed over the othe SVG elements. Now, I don't know how often I will be making this map. But it will certainly won't be often (not more than once a month) (so there is no need for squeezing out performance). Also once I have the map data (coastlines) I won't need to update them again. > > And about the SVG. > You mention post-processing in Inkscape. Was this to add your points? > Perhaps that can be automated in an earlier step? Probably more > question about output once we complete the other requirements > discussion. I add the points in the SVG by scripting (just appending them in the right place). I though to use Inkscape, so that I can easily adjust things like colors, alpha channels or objects, or increase the stroke of paths. With many points, Inkscape can be rendered unusable. I can always import them in Gimp (and get a raster image), so as long as I format the SVG the way I want, there won't be a problem. Thanks for your time guiding me through. I am not very experienced with handling and visualizing GIS data, so I am not familiar with the possible workflows and combination of tools to produce the outcome I want. Thanks again :) Regards Vangelis _______________________________________________ newbies mailing list [email protected] http://lists.openstreetmap.org/listinfo/newbies
