(1) abstract geometry; (2) storing geographic data in projected coordinates; (3) a generic ESRI term for vector features; a class for "geometry" objects.

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1answer
459 views

Map projection lat, lon to pixel?

I'm trying to find the concave hull of a lat, lon pointset but when I project my points on my map it doesn't look like expected. I've tried a lineare projection and a spherical projection. My data is ...
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2answers
1k views

How to convert Geometry type column to degree Minutes Second in SQL Server 2008 R2

I have shape column of type geometry and I want to convert X and Y coordinates into Degree Minutes Second format using SQL query and i am using sql server 2008 R2. Currently I got Lat and long using ...
2
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1answer
134 views

Which fields are standardized to describe a ShapeFiles feature?

I would like to store data into a database which is available here either as JSON or as ShapeFiles. The JSON looks something like this: { "type": "FeatureCollection", "features": [ { ...
2
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1answer
81 views

Where would a perfectly vertical vertical tunnel through the earth come out?

I am a programmer. I have a point P1 (lat,lon) given by GPS (WGS84) and I want to know the location of a point P2 if I make a straight line from P1 to the other side of the earth. I have read some ...
2
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2answers
966 views

Why do I get wrong length using STLength on MultiLineString?

I have 2 MultiLineString representing the a route (first is driving there and the second is the return way) . MULTILINESTRING ((34.787315938035292 31.318235314177119, 34.788431415005249 ...
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1answer
716 views

How to perform a cascaded combine from python script in QGIS?

I'm working with a large dataset, and I need to be able to combine up to 400,000 polygons. I have been using the QgsGeometry::combine(QgsGeometry* geometry) function and simply looping over all ...
2
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1answer
823 views

How to get point x and y geometry from a shapefile?

I have a shapefile of US Cities and I want to get the X and Y coordinate of EACH city in that shapefile. I've tried this: for city in city_cursor: geom = city.Shape point = geom.getPart() ...
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3answers
345 views

How to test if geometry is inside another?

I need to tell whether geometries from a shapefile are inside other geometries or not. For example, I want to test if there are trees (represented as points in trees.shp) inside the urban areas ...
2
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3answers
826 views

arcpy: get list of adjacent lines per line

I am working with polylines with hundreds of thousands of features, and would like to write a script that returns the OIDs of all lines adjacent (intersecting with) each line. I have been ...
2
votes
1answer
3k views

How to fix incorrect SRID of the geometry column? [duplicate]

I've been told to use AddGeometryColumn to properly add a column with correct/preferred SRID. however I wonder if it's possible to fix/change the current column instead of adding a new? If there's no ...
2
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2answers
728 views

Geoserver uses geometry, not geography

When using a SQL database as the store, Geoserver requires that the spatial data are stored in a geometry, not geography column. Naturally, as we are dealing with geospatial features and not just ...
2
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1answer
1k views

How to create multipart line and polygon with interior ring in arcgisscripting?

My objective is to swap X,Y coordinates of feature classes using Python and arcgisscripting. Based on help examples, I managed to write script which reads and writes all geometry types. The problem ...
2
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1answer
240 views

LinearRing getVertices implementation

I'm fairly new to OpenLayers so please excuse me if this is an ignorant question. I'm curious why the LinearRing getVertices implementation getVertices: function(nodes) { return (nodes === true) ...
2
votes
1answer
477 views

polygon map overlay algorithm

There are many algorithms for binary map overlay operation in vector data format which take two layers of map and produce resultant layer i.e overlaid layer as output. I am wondering whether there are ...
2
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2answers
134 views

MMP of geometries

MBR is used for extent of geometries.. then what is the use of MMP.. is it for visualization the objects?
2
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1answer
28 views

Creating PolylineZ in arcpy

The script below is slightly modified "Polyline example" from ArcGIS help http://resources.arcgis.com/en/help/main/10.1/index.html#//018z00000008000000 import arcpy # next 3 lines are new from arcpy ...
2
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1answer
54 views

How to know if two geometric figures are approximately equal?

I would like to know how to determine if two geometric figures (the_geom) are approximately equals. By the way, I'm working with Python, PostgreSQL and Postgis I have the following geometries: ...
2
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1answer
88 views

QGIS Python - raster as point layer, coordinates issues

I would like to create point layer for storing values retrieved from a raster file. My idea was to iterate through all raster cells. If cell value is different than NULL, I wish to create a new point ...
2
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1answer
62 views

Difference between: join, merge and group

Suppose it is desired to make polygons A and B, and their respective attributes to be one unique polygon C. What is this GIS operation called? Is there any difference in GIS terminology about ...
2
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1answer
73 views

Python library for geometrical calculations using with GRASS GIS?

I have to do some geometrical calculations in 2D(point, lines, line segments and intersection points) in Python, and then use it in GRASS GIS. What is the best library to use for it? I'm trying with ...
2
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1answer
604 views

How to perform SQL query using .STContains in MS SQL Server

I have a table that stores polygons and a table that stores points with a value field. Both sets of data are stored using the Geometry type in MS SQL Server. I have a simple requirement - I need to ...
2
votes
1answer
33 views

finding the nearest point outside a series of geometries

I have db with a very large amount of geometries (circles), most of them overlapping. I'm trying to come up with a way to find the nearest point (from your current location) that is not within any of ...
2
votes
1answer
225 views

How to get the width and height of a rectangular polygon in PostGIS

I have a table with point features saved in the my PostgreSQL database, and I can run the following query to get the extent of the point features and I turned the extent back into a geometry: SELECT ...
2
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1answer
151 views

Getting geometry of drawing in ArcGIS Server JavaScript API

To me, ArcGIS Help and Online Resources is always full of unneccessay information and missing some important points. For example there are lots of samples for drawing but I couldn't find any thing for ...
2
votes
1answer
221 views

Center point approximation of a polygon

I would like to get a center point approximation of a set of polygons so I can do a NN lookup to use for assignment instead of a point in polygon query. Lets say I have this set of polygons: I ...
2
votes
1answer
532 views

Combining polygon geometries with python and QGIS segfaults

I am trying to combine polygons, using Qgis 1.8, and every time I run this script in the python console, I get a segmentation fault. Here is the script: from PyQt4.QtCore import * iface = ...
2
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1answer
332 views

How to modify the coordinates of a SHP geometry using Geotools?

I have a shapefile with some polygons. I would like to change the height for this elements using Java. The rest of the attributes should be the same. I've thought using GeoTools but I haven't found ...
2
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1answer
118 views

Which is better for storage? Geometry column or varchar?

Objective: Need to store and retrieve a list of geometries from the database. Basically these are drawn by the user using OpenLayers which I would like to save and present again as a list (kind of ...
2
votes
1answer
524 views

Geometry valid in PostGIS turns out to be not valid in Oracle

Geometry is in PostgreSQL database. It is valid. Geometry is exported as GML and then inserted into Oracle database. Then function SDO_UTIL.RECTIFY_GEOMETRY(geometry, tolerance) is called, which ...
2
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1answer
1k views

How to make a predetermined Polygon (Circle) From 4 Coordinates, The Radius and Center Longitude and Latitude in Openlayers

I know how to make a predetermined Polygon in Openlayers (see below). Please have a look at http://studio.netnrg.co.za/dev/rnd/blake.loizides/openlayers var feature2 = new ...
2
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3answers
760 views

How do i find out geometries for areas?

I was wondering if anyone could help me out with a website which I can use to get geometries for a area. What I'm looking for is something like google maps where I can drag a cursor over a area of the ...
2
votes
1answer
33 views

SQL Server Geography Query works but Geometry Query Does Not - Different Tables, Similar Schemas

I am trying to get a Geometry query to work. A similar Geography query works fine but I must work with a table that uses a Geometry type. Although the Geography version returns lots of records as ...
2
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1answer
43 views

TSQL Geometry Query Requires conversion to string

If I specifically define some polygons and check for containment, I get a correct result: DECLARE @g geometry; DECLARE @g2 geometry; SET @g = geometry::STGeomFromText('POLYGON((407305 100826.5, ...
2
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2answers
110 views

How to handle coordinates accuracy in ArcGIS

I am creating very basic rectangular polygon using very basic a Python code nCols,nRows=100,100 corners =[[0,0],[0,nRows],[nCols,nRows],[nCols,0],[0,0]] ...
2
votes
2answers
104 views

Is there a PostGIS function to get a tangent and normal line?

I'm looking for a function that will return a tangent (and normal) for a LINESTRING in PostGIS. I think this is the 3rd time I've come across the need for this function and everytime, I end porting ...
2
votes
1answer
115 views

Add XY Column in QGIS [duplicate]

Following on from a previous question of mine, where I was given coords in degree-mins, I have successfully converted them to decimal degrees, thanks for the help. I have created a CSV file from ...
2
votes
1answer
281 views

QGIS 2.2 rendering problems

i have a problem with some geometry. When i run the check geometry validity i get an error coming back that the rings are not closed, so recangular forms that i have surveyed are showing up as ...
2
votes
3answers
411 views

Fastest way to join points table to polygons tables in ORACLE

I have two tables in 11g oracle db, one with points geometry, one with polygons. Currently I need to enrich the points table daily with the name of the polygon (country) that the point is inside, but ...
2
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2answers
207 views

OSM linestring shown as point

I have loaded the following file http://openstreetmapdata.com/data/coastlines to postgreSQL. In visual studio with gdal/ogr and geos enabled: SELECT geom FROM waterpoly WHERE geom IS NOT NULL LIMIT ...
2
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1answer
1k views

PostGIS Select Union of Polygons

I have a Postgres 8.4 PostGIS 2.0 enabled database and I've loaded it up with a bunch of shapefiles. I'm trying to get the database to do on-the-fly unions of geometries. Here is the query I'm ...
2
votes
1answer
426 views

GML - Multi-geometry validation

I'm doing the test to introduce multiple geometry in a WFS service using GML. For now the simple geometry is functional, but I still have some bugs with multiple geometry. I think it may come from my ...
2
votes
1answer
635 views

How to split zAware polyline by points programmatically with C#?

I'm trying to split a polyline by the boundaries of a polygon using IPolyCurve2.SplitAtPoints using C#. The polyline I'm trying to split is zAware and holds elevation values at a regular interval. ...
2
votes
2answers
193 views

Programmatically change geometry column in OpenLayers WFS layer

is there a way to programmatically change the geometry column on which a WFS layer is based and displayed? WFS (from GeoServer) is correctly returning me two geometry columns, I want to change "on ...
2
votes
1answer
480 views

Remove stale/obsolete geometry columns from the geometry_columns table

I understand that the function Populate_Geometry_Columns() inserts records in the geometry_columns table for geometry columns that are not yet listed there. However, an invocation of ...
2
votes
2answers
745 views

Updating polygon geometry: deleting inner rings with python

I've searched, but can't find clear explanations how can I simply delete inner rings from existing polygons with python or extract outter rings and overwrite the geometry. Seems GDAL/OGR should be the ...
2
votes
1answer
566 views

The minimum bounding circle of geometry that crosses the 180th meridian

Background: I've been given a task where I have to calculate the minimum bounding circle of Alaska (for the purpose of running a Roeck test). I'm using the Census' state level geometries available ...
2
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2answers
59 views

Merging lines (that might cross) at common endpoints without multi-part features in the result

I have a polyline dataset I'm trying to merge / dissolve segments based on an attribute into continuous single lines. The problem is that some of those segments cross each other but need to be ...
2
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0answers
35 views

how to orthogonalize building outlines

I'm looking for a way to orthogonalize building outlines which I've extracted from a high-res DEM. I'm using the FOSS GIS stack (QGIS, GRASS, SAGA, PostgrSQL, PostGIS) and can code in Python (or ...
2
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0answers
47 views

Reverse parameters of a projection map

I'm user of a soaring simulator named "Condor Soaring". This simulator is at the center of a community of enthusiastic people who build sceneries (landscapes) which represents quite accurately real ...
2
votes
0answers
176 views

QGIS : cannot change the z-coordinate of a point shapefile using the wkb geometry format

I am using QGIS Desktop 2.5.0-Master with GDAL/OGR 1.11.0 on a windows 7. I am working on a little pyQGis script that should modify the z-coordinate of points in a vector shapefile based on a value ...