A library providing vector geometry services

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26 views

gTouches error without geometry error?

I have a map showing administrative boundaries (available here). I've loaded it into R and have attempted to run gTouches (from rgeos) to determine which areas are adjacent to which, but receive an ...
1
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1answer
24 views

Gdal+Geos point in polygon test fails under MinGW64

I have to build a grid of points and remove the points that falls inside a polygon. Polygons are defined in a ESRI shapefile, points are in a list. This is how I make the test: OGRLayer *layer = ...
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1answer
66 views

GEOS_ERROR: TopologyException: Input geom 1 is invalid: Self-intersection at or near point

I'm using GeoDjango (but I guess this is from the geos library). I have a set of polygons that compose a city surface and I want to merge them into a single one. The code looks like this: polygons = ...
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2answers
53 views

How do I import geos from shapely? [closed]

I clearly have geos installed under shapely, since I downloaded "Shapely-1.4.4.tar.gz". Also, the result can be seen in my directory in the correct path: ...
2
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1answer
37 views

Shapely's simplify won't simplify any more

I have a multipolygon in shapely, and I want to simplify it until it has less than a certain number of points. When I use the preseve_topology=False argument to geom.simplify, I can get the number of ...
4
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3answers
103 views

Geometric Operations in GIS Systems

I have worked with 2D geometry for CAD - My questions are general and relate to understanding operations on geometric entities (lines). Should geometric operations such as line-line intersection be ...
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1answer
37 views

How to find points present in one layer but not in a second layer, using ArcGIS?

I have two layers, A and B, with B consisting of a proper subset of the points in A. How can I produce a third layer, C, consisting of just those points found in A but not in B. In R, I would just ...
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3answers
939 views

PostGIS non functional on Ubuntu 14.04

I am unable to create the PostGIS extension on new databases in Ubuntu 14.04: $ psql pg_testing -c "create extension postgis" ERROR: could not load library ...
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1answer
167 views

Empty geometries in GEOMETRYCOLLECTION

I just noticed some strange behavior in PostGIS, with respect to WKT parsing. A GeometryCollection containing 1 or more empty geometries postgis_test=# SELECT ...
0
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1answer
554 views

How to use Google Maps projection with GeoDjango/PostGIS

I am building a web service with GeoDjango which involves user submitted events including a location. I created a model field for my location using django.contrib.gis.db: location = ...
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2answers
32 views

geos_ts_c.cpp + spatialite Error

select distance(T1.Geom,T2.Geom) as Distance, T1.POI_ID, T2.LINK_ID from temp1 as T1, temp2 as T2 where T1.POI_ID = T2.POI_ID AND Distance < 100 temp1 having point geometry temp2 having line ...
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1answer
97 views

3D functions with SFCGAL in PostGIS

I have this setup: "POSTGIS="2.1.2 r12389" GEOS="3.3.8-CAPI-1.7.8" PROJ="Rel. 4.8.0, 6 March 2012" GDAL="GDAL 1.9.2, released 2012/10/08" LIBXML="2.7.8" LIBJSON="UNKNOWN" TOPOLOGY RASTER" on ...
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0answers
49 views

How to get full 16 bits range using RasterSymbolizer and ColorMap ramp?

I am attempting to get the full 16 bits values of my DEM (stored as TIFF files) rendered in WMS tiles (png format). For this I use GeoServer 2.5 and a RasterSymbolizer with a ColorMap of type "ramp". ...
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0answers
96 views

GEOS assertion failed

The following script fails, if I import the 'rasterstats' library. import rasterstats import ogr geom1 = ogr.CreateGeometryFromWkt('POLYGON ((415924.806155724043492 ...
2
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1answer
175 views

Installing QGIS 2.0 with the newest gdal and geos libraries

I want to install QGIS 2.0 on Ubuntu 12.04 LTS. I followed these steps until the final installation command. Before I compiled gdal 1.10, geos 3.4.2 and grass 6.4.3 on my own. In the synaptic ...
3
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1answer
179 views

Ubuntu Newbie I am frustrated trying to install (all things GEOS) WEB-GIS

I am new to ubuntu SAUCY and I must confess the transition from windows has not been really easy for me. on windows everything seems pretty much straight forward but I am getting frustrated because It ...
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2answers
304 views

Building CartoDB from source using updated dependencies on Ubuntu 13.10

I am attempting to build CartoDB from source on an Amazon VM for the first time in my life. For purposes of sanity, I want to use the same instance/database of postgres for both CartoDB and all of my ...
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1answer
209 views

Update GEOS to 3.4

I want to use the rgeos function gDelaunayTriangulation (which requires GEOS 3.4) on my Mac, but when I load rgeos it says: > library(rgeos) rgeos version: 0.3-2, (SVN revision 413M) GEOS runtime ...
3
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2answers
218 views

geospatial libraries like postgis

I'm pretty comfortable with postgis, but I realized that for part of my application, having a database is pretty heavy. I'd like to be able to take a stream of Point objects and check against an in ...
2
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1answer
802 views

Problem with loading OSM planet into PostgreSQL

I try download OSM planet into PostgreSQL database. I do all steps from instruction http://switch2osm.org/serving-tiles/manually-building-a-tile-server-12-04/ I also modify string "kernel.shmmax" ...
2
votes
1answer
753 views

How to update to QGIS 2.0.1 on Mac?

I'm trying to upgrade to the newest version of qGIS but get the following error message when I open the installer: QGIS requires the GEOS framework version 3.4 or newer. I've had no luck ...
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2answers
2k views

Dissolve polygons in QGIS (GEOS) with tolerance

I have a polygon vector layer representing the area inundated in a flood. The layer has been produced in a such a way that some of the areas are composed of multiple smaller touching polygons (see ...
5
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1answer
84 views

What are lazy geometries

What are "Lazy Geometries"? How are they different from other types of geometries? I'm an experienced Python/Django developer but am very new to the world of GIS, and understand that this is a ...
4
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3answers
251 views

Install Shapely with GEOS on heroku

I have a web mapping app running on Heroku. My app is written in python. Using pip I was able to install various pure python libraries that were needed. I would now like to install Shapely too. ...
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0answers
188 views

Why does polygon.intersection(complex_linestring) split the linestring and mess up Z?

I have a complex (self crossing) line with Z values which I'd like to truncate to the area inside a box. The problem is Shapely splits the line into simple (non-crossing) sections and the Z value at ...
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0answers
378 views

Get the distance between 2 WGS84 GEOSGeometries

I currently want to check if 2 given GEOSGeometry objects of type Point are within 100m of each other. (length flexible) Looking at previous asked questions on this topic, most of the answers were ...
3
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2answers
589 views

Checking if a point is in a circle

I'm using shapely to check if a point is in a polygon, but I also need to check if a point is in a circle. Checking the docs, I don't see how do that... Maybe I could create a circle? circle = ...
2
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2answers
146 views

Why are the results different for the same point using GEOS Point.transform and Postgis ST_Transform?

I'm trying to define a default point setting for OSM layers in my application and I want users to be able to define the default latitude and longitude in EPSG:4326. What I'm doing right now is to use ...
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0answers
67 views

GEOS: how to access Noder functionality through the C API

All this stuff looks rather useful: http://geos.osgeo.org/doxygen/classgeos_1_1noding_1_1Noder.html However, from the GEOS README file: The C++ interface should not be used directly; the geos ...
4
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1answer
623 views

How to use GEOS/C++ to efficiently find all point pairs closer than a threshold?

Can anyone tell me how to use GEOS/C++ to efficiently find all point pairs in a dataset closer than a threshold distance d? I suspect this might involve quadtrees or rtrees but not quite sure how ...
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1answer
418 views

Mapnik WKT rendering problem

I have a rendering problem with the mapnik GEOS plugin. I try to input a polygon WKT definition containing floats with around 16 digits. Mapnik however does not render these. When I decrease the ...
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1answer
311 views

python qgis.core import error caused by spatialite libraries

I have an error when trying to import qgis.core to python: >>> import qgis.core Traceback (most recent call last): File "<stdin>", line 1, in <module> ImportError: ...
8
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0answers
268 views

Solutions for fast operations on large GIS datasets [duplicate]

Possible Duplicate: Acquiring ArcGIS-like speed in Postgis I have been using PostGIS 2.0 for all of my GIS operations. PostGIS is an excellent GIS database, but no matter how I format my ...
4
votes
1answer
733 views

GEOS Python: Taking Union of several geometries

I am using the GEOS/OGR library in Python. I have files full of geometries that overlap, and I want to convert these to files of geometries that don't overlap. The way I have been approaching this ...
4
votes
2answers
639 views

is there a way to tell if two linestrings “really” intersect in JTS or GEOS

In JTS (or GEOS) you can't tell if two linestrings really cross each other. The result is exactly the same whether the lines simply have a point in common but don't cross or if they really cross. Is ...
2
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1answer
188 views

Converting 2D shapefile to Equal Area Projection?

I have thousands of shapefiles with coordinates in lat/long (-180 to +180 x, -90 to +90 y), that contain polygons of which I wish to calculate the area. I'm using the Python GEOS/OGR/GDAL API. If I ...
4
votes
1answer
703 views

Wrap GEOS functionality into python

I've been looking on how to get GEOSExtractLine available in python. I looked into Shapely source to if it was available for it, but it's not. I'm trying to wrap this funcionality into Django, much ...
2
votes
3answers
818 views

Accessing GEOS functions in Python

The issue: I am using Windows 7, 64-bit operating system with Python 3.2. I must continue to use Python 3.2 because of a dependency with another API. I need some functions in GEOS that are not ...
0
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1answer
148 views

How to solve “Error creating GEOS Coordinate Sequence” in Postgis?

When I run this query: TRUNCATE sertaozinho.apps; INSERT INTO sertaozinho.apps (id,tipo,the_geom) VALUES (DEFAULT, 'app' ,( SELECT st_union( CASE WHEN area.cobertura = 'lago' THEN ...