An additional thought - with JTS or Geotools, it should be possible to eliminate the ogr2ogr conversion to GML and rather parse the (simplified) shapefile directly. However, this is probably not urgent. Here is a quick presentation of the two libraries: http://haitaoblog.blogspot.com/2008/01/jts-topology-suite-geotools.html
On Thu, Nov 11, 2010 at 7:32 PM, Knut Staring <knu...@gmail.com> wrote: > On Thu, Nov 11, 2010 at 6:05 PM, Jan Henrik Øverland > <janhenrik.overl...@gmail.com> wrote: >> Hi, >> I would like to suggest that we finally remove the map source types >> "GeoJSON" and "Shapefiles" from the GIS client. They are not able to offer >> most of the functionality that will be implemented in the future and even >> maintaining them as they are would hamper the development of new >> functionality considerably. However, overlays could still be loaded from >> local geojson files. >> In other words, I would like to control the geojson input to the thematic >> widgets completely by letting our own server produce it. > > I think this is mostly ok, but I also think it requires us to improve > the importing and limit it to one polygon layer and one point layer - > see below > >> This geojson may contain data from Geoserver, health surveys etc. > > Not quite I understand - you mean we can import data from such > sources? As far as I know, that is not the case now - we can only > import from GML. > > Recent discussion on the list has revived the need for more support > for data loading. I think the hierarchy is a good place to start > improving. I have come to realize that it is actually a bit stupid to > import polygons at different levels (nation, province, district, > subdivision etc), because the higher levels should logically > correspond to fusion of lower level polygons. Therefore, I suggest the > following algorithm for starting in a new country: > > 1) Start with the lowest level for which you have polygons (e.g. > shapefiles), and simplify it to an acceptable degree (using e.g. > Mapshaper) > > 2) Create the organizational hierarchy in a standardized .xlsx > template with a worksheet that has columns like this: > > Country, Province, District, Subdistrict, Facility (the number of > levels and their names will vary - this should probably be specified > in a front worksheet. > > Make sure the names of the level in step 1) correspond exactly to the > shapefile names. > > Also, there will be two columns at the end, immediately after > facilities, which can be filled with point coordinates if available. > > 3) Upload the Excel file to DHIS2, which will run it through an XSL > transformation that builds the whole hierarchy > > 4) Upload the simplified polygon layer. DHIS2 will not only poplulate > the orgunits for that level as it does currently, but also > automatically *all levels above". > > For step 4, we probably need to use GIS Java capabilities like JTS or > Geotools (maybe even steal some code from Geoserver, uDig or OpenJump) > http://lin-ear-th-inking.blogspot.com/2007/11/fast-polygon-merging-in-jts-using.html. > With such tools in place, we could probably also do the simplification > in step 1, but it is actually quite good for people to have the > manually guided visualization that Mapshaper offers instead of > automated generalization. > > Knut > -- Cheers, Knut Staring _______________________________________________ Mailing list: https://launchpad.net/~dhis2-devs Post to : dhis2-devs@lists.launchpad.net Unsubscribe : https://launchpad.net/~dhis2-devs More help : https://help.launchpad.net/ListHelp