Brian, Thanks for running the clean command on the themes!
For the upcoming 1.3.1 release of Natural Earth our format is now "ne_" prefix on each of the 10m, 50m, and 110m scale set themes. _Nathaniel On Fri, Feb 25, 2011 at 01:00, Brian Hamlin <[email protected]> wrote: > Hamish- > > I am just finishing a set of tables cleaned via st_MakeValid() in PostGIS > 2.0b > Conveniently, I renamed the tables as c10m_this_that > so as to no longer need the quoting.. > > I wonder how many people use the .shp files.. > or how we should name those.. > > -Brian > > > > On Feb 24, 2011, at 8:21 PM, Hamish wrote: > > Nathaniel wrote: >> >>> I'm not seeing the any geometry errors in ArcGIS (the horror, >>> the horror) on the 10m lakes theme fresh off the website. >>> >> >> Arc is not a topological GIS so it misses (or ignores) many >> errors in the data which cause problems when the data is used >> in other ways which demand topological correctness. >> ([river] network analysis, etc) >> I understand that Natural Earth is mainly focused on cartographic >> needs, but ... >> >> >> The 1.3 version that was released a couple weeks ago should have >>> resolved most the obvious topology errors on the themes that >>> were ID'd to me before. If you want to run a custom repair >>> geometry / topology script on them as they're imported to the >>> LiveDemo system, sounds fine to me. >>> >> >> Loading a fresh download of 10m-lakes.zip into GRASS GIS (which >> is fully topological) exposes a number of errors in the data. >> Probably most are due to overlapping areas; small sliver areas >> resulting from those after "flattening" are appear below as >> areas without centroids (no attributes). >> >> GRASS65> v.in.ogr dsn=natearth/10m_lakes.shp out=ne_10m_lakes >> [...] >> Building topology for vector map <ne_10m_lakes_tmp>... >> Building areas... >> 100% >> 1708 areas built >> 1472 isles built >> Attaching islands... >> 100% >> Number of nodes: 2627 >> Number of primitives: 4691 >> Number of points: 0 >> Number of lines: 0 >> Number of boundaries: 4691 >> Number of centroids: 0 >> Number of areas: 1708 >> Number of isles: 1472 >> Number of areas without centroid: 1708 >> ----------------------------------------------------- >> Find centroids for layer: 10m_lakes >> ----------------------------------------------------- >> Write centroids: >> 100% >> WARNING: 82 areas represent more (overlapping) features, because polygons >> overlap in input layer(s). Such areas are linked to more than 1 >> row in attribute table. The number of features for those areas is >> stored as category in layer 2 >> ----------------------------------------------------- >> 1358 input polygons >> Total area: 1.26155E+12 (1708 areas) >> Overlapping area: 2.02361E+11 (82 areas) >> Area without category: 2.39549E+10 (240 areas) >> ----------------------------------------------------- >> Building topology for vector map <ne_10m_lakes>... >> Registering primitives... >> 3489 primitives registered >> 138259 vertices registered >> Building areas... >> 100% >> 1708 areas built >> 1472 isles built >> Attaching islands... >> 100% >> Attaching centroids... >> 100% >> Number of nodes: 3253 >> Number of primitives: 3489 >> Number of points: 0 >> Number of lines: 0 >> Number of boundaries: 2021 >> Number of centroids: 1468 >> Number of areas: 1708 >> Number of isles: 1472 >> Number of centroids outside area: 3 >> Number of duplicate centroids: 5 >> Number of areas without centroid: 248 >> >> #extract problems to another layer: >> GRASS65> v.extract in=ne_10m_lakes out=ne_10m_lakes_problems layer=2 >> >> displaying that extract shows problems are all in the northern >> hemisphere, the Great Lakes of N.America being the biggest >> pile of red ink. (Lakes Ontario and Erie look ok though) >> >> a map layer created with "v.clean error=problem_areas_map" can >> help quickly pinpoint where the problems are. >> >> e.g. an easy place to start looking are the finger lakes within >> this bounding box, all of which show errors: >> >> north: 43N >> south: 42:18N >> west: 77:24W >> east: 76:12W >> >> (south of Rochester-Syracuse, NY) >> >> >> best, >> Hamish >> >> >> >> >> >> >
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