(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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31 views

WKBreader reuse - jts 1.9

I'm having some bad behavior reusing wkbreader. The context as of a single threaded as I use threadlocal wkbreader. I get parse exception on some geoms. When I create a new wkbreader for each ...
4
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2answers
822 views

Multilateration Code

I am currently writing some code to do multilateration using TDOA and currently struggling and wondering if anyone has any reference code that can be used as a test case with some sample data that I ...
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1answer
461 views

SQL Geometry Query similar to Select by Centroid

Does anyone know if it's possible to query SQL geometry by something like 'centroid of polygon'...similar to ArcMap's select by location? I'm using SQL Server 2008 R2 as the DBMS. I have two polygon ...
2
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1answer
731 views

Is it possible to get a binary geometry from PostGIS?

PostgreSQL (via C# Npgsql driver) returns geometry column (PostGIS) like a hex string (EWKB as I understand) for this query: SELECT ST_Transform(geometry, 4326) FROM myGeometries; Result (for ...
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1answer
82 views

How to identify and highlight invalid geometries?

I'm am trying to clean/edit shape files that were created by algorithm in Qgis. My problem is when I try to split some polygons,they have invalid geometry. Is a way to identify these error maybe in a ...
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130 views

Prevent self-intersecting loops when exporting polygon layer from ArcSDE to File Geodatabase?

I am using ArcGIS 10.1. The source data is housed in an ArcSDE instance that does not allow self-intersections. When I export this data to a file geodatabase and run check geometry ...
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0answers
54 views

PostGIS automatically creating geometries after importing using QGIS DB Manager

I have a shapefile consisting of linestrings, in which some of the features have null geometry. Yet, after importing it to PostGIS, using QGIS' DB Manager, a geometry is created for those features ...
3
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2answers
121 views

How do you determine how straight a LineString is? [duplicate]

I have a bunch of LINESTRINGs and need to classify them based on how strait they are. My idea is to compare the length of the LINESTRING to the distance between the first and last POINTs. I'm ...
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1answer
45 views

ogr: what is the advantage of using `geom.Clone()` over `geom`?

What is the advantage of using geom.Clone() over geom? Simple example: geom = link_feat.GetGeometryRef() newfeature.SetGeometry(geom.Clone()) # or newfeature.SetGeometry(geom) ...
2
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1answer
410 views

How to split circles in 8 quadrants

I am using ArcGis 9.3 and I need to split a large number of circles in quadrants. The circles corresponde to a 200m buffer of a point layer and, for each point, I need to split the buffer in 8 ...
2
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1answer
126 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
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1answer
97 views

Decimal Degree data erases itself between edit sessions in QGIS

I have a shapefile with point data. I calculate the $x and $y of the points successfully I save the changes and close the edit session. Once I reopen the attribute table, the data after the decimal ...
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1answer
317 views

Configuring Geoserver to use a specific postgis geometry column as the default

I have a PostGIS table with two geometry columns, both multipolygon but one with SRID 4326, the other 3857. When publishing the table in Geoserver, I realize that Geoserver defaults to using the first ...
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1answer
38 views

Postgis add Geography to function()?

i was wondering im getting different results when using geography() on different positions within a query. So, whats the most accurate way of forcing geography() over a functions with geometry ...
2
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0answers
64 views

PostGIS does not export shortest path to Shapefile

I am trying to draw a bunch of lines overlaying the globe map in a WGS84 projection. To this effect I have created a PostGIS DB with a table that has one column containing linestring data. My problem ...
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2answers
100 views

How to disable “Simplify geometry” via Python?

After I've loaded a layer from a table in my db I'd like to disable the 'Simplify geometry' (found in Layers/Properties/Rendering) programatically using Python. I've tried several versions of ...
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0answers
65 views

Merging parcels but keeping Geometry seperate

I am working on updating a parcel layer we received for a project, and I have duplicate parcelID's for parcels and I have been merging these to create 1 parcel as to not have duplicate ID's. My ...
3
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1answer
1k views

converting/parsing geojson into com.vividsolutions.jts geometry

Does any has any experience with converting string geojson into com.vividsolutions.jts geometry object (point, polygon, etc). Maybe there is some java library I cannot find. Greets!
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2answers
83 views

How can i change the geometry of an existing layer?

I work with Qgis, v. 2.0.1. I have a point layer in which I have structures that could be represented as lines or polygons, but at the moment they are represented as a group of points. I know I can ...
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3answers
156 views

Geometry vs geography for line-to-polygon intersection

I have two WGS84 NAD83 shapefiles, one polygonal, the other containing lines: Geometry: Polygon Feature Count: 1294 Extent: (-79.761059, 44.991143) - (-57.105486, 62.582865) Layer SRS WKT: ...
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3answers
157 views

Invalid geometry message when using Difference tool

I am using the Vector \ Geoprocessing \ Difference tool to get the resulting area when taking a) current ground disturbance away from b) historic total ground disturbance to give c) what has been ...
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0answers
28 views

Quickest method for determining which postcode is 2 miles north of original postcode? [duplicate]

What is the Quickest method for determining which postcode is 2 miles north of original postcode? For instant L17. I know how to determine the distance between 2 points as below, but the above ...
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1answer
45 views

Hard to get my head around, generating average price for houses in each quadrant

I'm able to determine the average price of houses sold in a particular area (like the squares on image below) dependent upon postcode. Although I can generate the average sale price for a particular ...
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2answers
357 views

Is there an average size for British postcodes?

Is there an average size for British postcodes? Or a method of determining the size for a particular British postcode? Thanks. Considering creating a related program and this would be valuable ...
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45 views

Speed drastically reduced when including geometry, is there a way to improve?

-- EDIT: Issue is that the shape files being used are at too small of a precision and way too large, output was 488M total, looking for different source -- I'm having some speed issues with a complex ...
2
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1answer
264 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 ...
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4answers
440 views

How to determine if an object is a circle

I have a polygon shapefile that consists of many different shaped features. I would like to identify only those shapes that are circles. Is there a way to do this? Is it a calculation I could do in ...
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1answer
91 views

Getting wrong value for area of geometry using Spatialite?

I am trying to implement a measuring tool on apple maps for IPAD. As a part of that i collect all the touch points on the map into an array and constructing a geometry object from that and then ...
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1answer
95 views

How do I convert OS coordinates (X and Y) to longitude and latitude coordinates?

How do I convert OS coordinates (X and Y) - Eastings and Northings to longitude and latitude coordinates? For example X and Y below X (Eastings): 347904 Y (Northings): 287484
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1answer
131 views

How do I figure out the grid references (Eastings and Northings) necessary to create a circular 1 mile radius around one location?

How do I figure out the grid references necessary to create a circular 1 mile radius around one location? For instance: Grid Reference: SO 47904 87484 X (Eastings): 347904 Y (Northings): 287484 ...
3
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1answer
206 views

How do I figure out the longitude and latitude coordinates necessary to create a circular 1 mile radius around one location?

How do I figure out the longitude and latitude coordinates necessary to create a circular 1 mile radius around one location? I don't mind how many coordinates that takes. For instance: Latitude = ...
0
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1answer
198 views

Get the vertices on a LineString either side of a point (Sql Server 2008)

I have a point that sits on top of a LineString, both Sql Geometry types. POINT('0.5 0.5') LINESTRING('0 0 NULL 1, 1 1 NULL 1') I want to find the vertices of the LineString that lie either side ...
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0answers
166 views

Using M 'Measure' value in SQL Server 2008

MS Sql Server 2008 geometry type supports adding Z and M values to geometry objects, including linestrings. However, I cannot find any way to make use of these values, since methods such as ...
3
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1answer
2k views

How to draw polygons from the python console?

I've been visiting and revisiting the page on geometry handling in the PyQGIS Cookbook: https://www.qgis.org/en/docs/pyqgis_developer_cookbook/geometry.html but can't seem to figure out how to get the ...
3
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1answer
276 views

Get geometry column back when counting points in polygon using PostGIS

I have two PostGIS tables: earthquakes and borders, which contain point data on earthquake locations, and polygons of countries in the world respectively. I want to try and count the earthquakes ...
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1answer
86 views

Adding geometry to rows with missing X,Y inArcGIS

I have a table with X, Y data that contains many rows with still missing coordinates. Now I would like to edit it in ArcGIS 10 and simply add the geometry for selected lines after identifying the ...
2
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1answer
838 views

Multipoint vs point PostGIS

Is it normal to use the geometry type 'multipoint' instead of 'point' knowing that I use it to store only one point. How can I convert from multipoint to point
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3answers
127 views

What is the PostGIS 2.x equivalent of the pre-PostGIS 1.5 ~= operator?

Stemming from my other question: When would a PostGIS geometry compare using ~= return true when ST_Equals returns false?, what is the PostGIS 2.x equivalent of the pre-PostGIS 1.5 ~= operator? It ...
2
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1answer
139 views

When would a PostGIS geometry compare using ~= return true when ST_Equals returns false?

I have a couple of featureclasses in a 10.2 geodatabase/PostgreSQL 9.2.2 database and I've been struggling with the FeatureCompare tool--it is telling me geometries are different on some features ...
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2answers
132 views

Problem - ST_AsGeoJSON return text with accolade

I am saving a result of ST_AsGeoJSON(..) into csv file. But the results I got can't be interrupted as an object later on. How can I polish and delete the accolades that I don't need. ...
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0answers
28 views

Is there a way of converting polygon vertices to points using GDAL python? [duplicate]

I have an ArcGIS standard license and I want to convert polygon vertexes to points in a script. Since I don't have a good enough ArcGIS license I've been using ET Geowizards to get the points. The ...
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2answers
551 views

Get the vertices on a LineString either side of a Point

I have a shapely LineString and defined a shapely Point which lies along the LineString. How can I find the vertices of the LineString which lie either side of the point? (split the line in two). ...
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0answers
178 views

Which geo-location available in Twitter data should I use?

I am extracting twitter location on my side.Few tweets has perfect location but in most cases additional details are available (i.e. Country,bounding_box,poly lines etc) So confused regarding ...
5
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2answers
200 views

Defining spatial operators (Equals, Disjoint, Touches, Within, Overlaps, Crosses, Intersects, Contains, Relate)?

Ok, I have to admit, I don't really delve too deep into the semantics of the spatial operators list below, I'm more of a user, I write software to drive the SQL most of the time and don't really think ...
3
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1answer
1k views

Multiple geometry columns for points, lines, and polygons in spatialite?

I'm rather new to the GIS world and even newer to Spatialite and trying to create a new DB for our application. I would like to create spatial index(es) on the geometry column(s), but our geometry ...
1
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0answers
139 views

Error When Generating INSERT Statements for Geometry Field SQL Server

I am populating a column of linestrings from a list of points in sql with which I use to create insert statements to populate an ID and a geometry field in a table. This creates a temporary dataset ...
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0answers
148 views

Inaccurate result while clipping on gis data

I am trying clip polyline data using a polygon geometry. I am using itopologicaloperator to do this task. However, resultant clipped data is off by 1 feet. Meaning that the polylines at the boundaries ...
9
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2answers
536 views

What is the precision of SELECT DISTINCT on PostGIS geometry column?

I wonder what the precision of the SELECT DISTINCT operator is on a PostGIS geometry. On my system, the following query gives me a count of 5, which means that the inserted points are considered equal ...
3
votes
1answer
417 views

Retrieve geographic coordinates from OSM imported data

We have just finished importing OSM data into our PostGIS (Postgresql) database. And we are having difficulty understanding the geometry of various shapes imported. We run a query to retrieve the ...
2
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2answers
209 views

How to convert Point coordinates into CSV format?

The GDAL documentation describes how to convert a ShapeFile into CSV data. The layer create options (-lco parameter) allows to prepend the coordinates of Point features to the actual attributes ...