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

learn more… | top users | synonyms

3
votes
0answers
141 views

What is the area that OGR extracts from the (geometry) shp files for polygons?

The ESRI July 1998 technical documentation for polygon shapefiles at page 10 makes no mention of either area measures or length measures (apart from byte/record-layout matters). Yet OGR enables me to ...
3
votes
1answer
480 views

OpenLayers: How to get *real* centroid of a Line Geometry/Feature?

I have declared a line geometry as: var lineString = new OpenLayers.Geometry.LineString([source,target]); then I am trying to get the centroid of this lineString as lineString.getCentroid(). But ...
3
votes
2answers
139 views

Find gap in / endpoints of linestring

I have a set of features of type linestring. I'm trying to polygonise the linestrings and assumed that they were closed (naive me :) ). Of course some were not closed and I'm trying to locate the gaps ...
3
votes
2answers
1k views

How to densify a polyline according to a specific length? [duplicate]

Possible Duplicate: Add vertices to lines I am using QGis 1.8.0 I would like to densify a polilyne according to a particular length of segment (ex. 200 m). I know it is possible with other ...
2
votes
2answers
874 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
votes
1answer
2k views

How to write point geometries with arcpy instead of gp syntax?

Can someone help me fix some code that simply writes points into a featureclass? It used to work in the older gp. syntax, but I'm having difficulties rewriting it in arcpy for ArcGIS 10.0. In this ...
2
votes
1answer
278 views

Use arcpy to check whether feature class geometry has ZM

I am looking for a programmatic way using arcpy to determine whether or not a feature class (FC) has Z and/or M geometry. It's easy enough to get the geometry type using the code below, but this just ...
2
votes
2answers
750 views

How can I create a multipoint geometry in QGIS?

I've got a Spatialite layer in QGIS with geometry type MULTIPOINT. Now I'd like to add some data in this table in the 'usual' way, so by doing multiple clicks in the map (e.g. left-click, left-click, ...
2
votes
2answers
374 views

Several questions about using spatial data?

If you have spatial data for SQL server, can you use the spatial data (both geometry and geography) in another application for instance ESRI ArcGIS? Is spatial data a standard that every GIS ...
2
votes
1answer
2k views

How to get the radius of a “circle” in Openlayers

How do you get the radius of a circle in openlayers? I have searched quite a bit and cannot find any resource for this. please help. Here is my code but I want the radius or circumference of the ...
2
votes
1answer
736 views

arcpy Geometry tools give incorrect results?

I'm new to python and arcpy but I've been trying to learn how to run geoprocessing tools using arcpy. I have (for this example) 2 shapefiles, a and b, which are both polygons. From plotting them in ...
2
votes
1answer
113 views

Outward buffering

I get the ConvexHull of a set of polygons using ST_UNION and ST_CONVEXHULL functions using PostGIS. I want to know how to create an outward buffer of the created convexhull in PostGIS?
2
votes
2answers
177 views

How to find multiple centers of gravity?

Say I have a number of customers in a geographical area, marked "c": Each customer has a Lat/Long. I would like to find x number of points, in the same space, that best serve the customers, ie. ...
2
votes
1answer
2k 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 ...
2
votes
3answers
84 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
votes
3answers
592 views

Polyline selection of features with angle turns up to a specified angle

I'm looking for an automated way to select line features that have specified angle between vertexes. That in order to check water mains layer -steel pipes can have only 45 or 90 degrees turns and I ...
2
votes
1answer
794 views

Can you explain this WKT multipolygon format?

I am confused by the output I'm getting from ogr2ogr when converting a shapefile to WKT. What I'm expecting to see is something in the form below (from Wikipedia): MULTIPOLYGON (((40 40, 20 45, 45 ...
2
votes
3answers
1k views

How to create Esri Flex Geometry from WKT

I am working with Esri flex 2.3 API, I am also using Abode BlazeDS for server side binding. I am sending a geometry as WKT from server into my flex client and I am looking for a way to convert the ...
2
votes
2answers
52 views

Copy geometry from one layer onto attributes of another?

I have two polygon layers, A and B, that have the same features but totally different attributes. I want to use the attributes from layer A, but I want them to have the more accurate geometry from ...
2
votes
2answers
46 views

Feature Geometry/shape changed event in arcObjects

I have a feature class(polyline). there are 5 features in the feature class. I want to get notification when user changed property any of feature of feature class. How it can be achieved ? I am using ...
2
votes
2answers
77 views

Query Features in Certain Direction

I have a polyline that I would like to query features that are on it's left, right, top, bottom. I am not looking for the features surrounding it but for features that are on a certain location from ...
2
votes
1answer
176 views

QGIS crash when I try print geometry

I do (it works): from osgeo import ogr inputds = ogr.Open(r'c:\temp.shp') inputlyr = inputds.GetLayer() for i,feature in enumerate(inputlyr): print i, feature.GetGeometryRef() Output: 0 ...
2
votes
1answer
235 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 ...
2
votes
1answer
4k views

Trying to convert geometry to geography keep failing in MSSQL 2012

In MSSQL I have LineString in Geometry type. When I try to convert it to geography using : ...
2
votes
1answer
1k 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
votes
3answers
3k views

Convert coordinates to geometry (polygon) using QGIS

I have an Excel sheet with grid data including geographical coordinates. I know that the coordinates represent areas, i.e., a multi(polygon). However, the data lacks geometry information. I'm looking ...
2
votes
2answers
84 views

How to create a PostGIS table with arc support compatible with QGIS?

In postgis database I have two tables - let's say 'polygons' (gid, the_geom,MultiPolygon,srid=2180) and 'lines' (gid, the_geom,MultLineString,srid=2180). I'd like to use "Add circular string tool" ...
2
votes
1answer
92 views

Create geometry from a result of intersection [closed]

Split a polygon in half with an extended line public Ipolygon CreatePolyFromIntersection(Ipolgon polygonA, Ipolygon bounradyThatcontainsPolylgonA, IFeature lmark){ ...
2
votes
1answer
76 views

Testing if Geometry is convex using JTS?

I'm using the Java Topology Suite and I'd like to efficiently check if a Geometry (a Polygon in fact) is convex or not. I currently do if (geometry.convexHull().equals(geometry)) but obivously that ...
2
votes
1answer
76 views

Geometry in QGIS 2.6

This might be a beginners question, but I could not find an answer on the internet. I drew a couple of polygons in a vector layer and I am trying to get some basic geometric information into my ...
2
votes
1answer
122 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
votes
1answer
331 views

Delete duplicate polygon nodes with PostGIS

I'm trying to delete duplicate nodes from a shapefile with QGIS, but after running the tool to delete it, nothing happens and shows the same errors. I thought that maybe importing to postgis could be ...
2
votes
1answer
313 views

Removing last point in polygon geometry using ArcPy?

This polygon was created from a grid of 500 x 500 meters, then Union, Generalize and Dissolve was used to arrive at this geometry, the laspoint not help me, I just want to have points on each vertex. ...
2
votes
1answer
118 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 ...
2
votes
2answers
284 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 ...
2
votes
1answer
645 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 ...
2
votes
2answers
2k 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
votes
1answer
152 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
votes
1answer
83 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
votes
2answers
1k 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 ...
2
votes
1answer
1k 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() ...
2
votes
3answers
531 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
votes
1answer
4k 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
votes
2answers
785 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
votes
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
votes
1answer
245 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
507 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
votes
2answers
136 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
votes
2answers
74 views

Calculating bounding box of given set of coordinates from Leaflet Draw?

I have values generated from Leaflet Draw plugin that look like this: { "type": "Feature", "properties": {}, "geometry": { "type": "Polygon", "coordinates": [ [ ...
2
votes
1answer
81 views

Get the number of bends of a polyline

I am trying to get the number of curves/bends of a polyline. I know that I can accomplish this by getting the vertices of the polyline, and check the from and to and compare their angles, if they ...