Tagged Questions

(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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11
votes
2answers
1k views

How to calculate the angle at which two lines intersect in PostGIS?

I want to calculate the angle between two lines where they intersect in PostGIS. The starting point for angle calculations in PostGIS seems to be ST_Azimuth - but that takes points as input. My first ...
8
votes
1answer
2k views

Postgis - Converting 'geometry_dump' data type to a 'geometry' type

I am working with a dataset of property boundaries that has had ST_Union() run on it, thus all the polygons appear as a multi polygon in one row of a table. I would like to separate these out so I get ...
4
votes
2answers
338 views

Fastest way to remove matched points

Hoping someone can see a faster way of doing this, because at the moment I'm averaging 9 hours per run for what I'm trying to do and well basically getting my behind chewed off by the boss :-) The ...
3
votes
1answer
975 views

How can I create an empty feature class in a file geodatabase based on the schema of an SDE feature class?

I have 150+ feature classes in SDE for which I need to create an empty feature class in a file geodatabase. For these feature classes I need to import the attributes and the name of the feature class ...
2
votes
2answers
2k views

Downloading Google Maps municipal geometry

When searching for a city on google maps, google is that smart it displays a geometry line on the boundary off the municipal. See this link: http://g.co/maps/23dz5 Is there a place in the google maps ...
1
vote
0answers
283 views

Create IPoint with Lat/Long in decimal degrees and Z in feet

I have written an ArcMap v10 AddIn that reads a folder of geotagged JPEG's and creates a new feature class where each point is the geotag information from on of the JPEG's. The issue is: The GPS ...
2
votes
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
votes
2answers
597 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 ...
3
votes
1answer
305 views

Is ST_GeomFromText better than providing direct geometry?

I have been working with postgis recently,and in my query if I use ST_GeomFromText it execute faster than running a sub-query to get geom. I thought ST_GeomFromText will be more expensive but after ...
27
votes
4answers
8k views

How to find the minimum-area-rectangle for given points?

The following is another problem that I am working on it these days. As you see in the figure, (BTW, I tried to make it self-presenter) the question is: How to find the minimum-area-rectangle (MAR) ...
29
votes
1answer
9k views

How to find the center of geometry of an object?

Well it might be a simple question. Given a set of 2D or 3D points, the question is: How to find the center of geometry of an object? According to the following figure, the center of geometry ...
6
votes
1answer
396 views

How to find the smallest-area ellipse circumscribing a convex polygon?

We are currently dealing with the problem of: How to find an ellipse circumscribing a convex polygon? Recent googling and lots of reading could not help me so much :(
3
votes
2answers
2k views

Extracting elevation from a TIN file with a point shapefile overlay

I have a TIN file that was built off of contour polyline shapefile (I think). I have a point shapfile with a few points. How can I extract elevation of the TIN file where the points occur? I am ...
2
votes
1answer
449 views

Convert point XY to page units XY using arcpy?

I am using arcpy to export PDFs from my ArcGIS Server application. I want to move a TextElement in my layout view to the centroid of a selected feature. I can get the centroid of the feature, but ...
1
vote
1answer
1k views

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

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 ...
0
votes
1answer
3k views

Area of an irregular polygon using side lengths

I have only lengths for the sides of an irregular polygon, can anyone tell me how I can measure the area of the polygon? Remember only lengths of all the sides , no angles or coordinates. Few forums ...
1
vote
2answers
3k views

How to initialize a WFS Layer?

Here is the code block (the layers are stored in Oracle database): var saveStrategy = new OpenLayers.Strategy.Save(); var adresspt_wfs = new OpenLayers.Layer.Vector("Address points WFS", ...
7
votes
3answers
12k views

Create a geography/geometry column from x and y fields - SQL Server 2008

Hy guys, I'm new in SQL Server 2008 and I hope you will understand my question/need. Thus, I have a table which contains 3 fields (Name, Lat and Long) in my data base (spatial). I want to create a ...
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 ...
7
votes
2answers
2k views

What is the best way to extract the geometry of a road from OSM data?

What is the best way to extract the geometry of a road from OSM data? The goal is to display segments of highway that are closed due to weather. The weather data consists of positions (in KM measured ...
2
votes
1answer
685 views

Using MS SQL 2005 as the data store in GeoServer

In my project, I am trying to set up a simple WFS service in GeoServer in order to create a layer consisting of point features. I have succeeded doing so with the points being stored in a shapefile. ...
1
vote
1answer
2k views

ArcGIS API for Silverlight - pass geometries to ESRI service

How would I test this service to find what it wants? ...
4
votes
1answer
3k views

Transforming geometry coordinates from SRID 4326 to SRID 3011

In SQLServer geometry field, I want to change the coordinates of geometry from one spatial reference system to another spatial reference system (from SRID 4326 to SRID 3011) by using ST_Transform. But ...
3
votes
2answers
8k views

How I get SRID from Geometry field

what is the function for getting SRID from Geometry field. I have inserted a shapefile into SQLServer table with Geometry field defined. I know the projection of shapefile is Swreff99_1800 ...
1
vote
2answers
1k views

what is the format of Geometry data type of SQLServer 2008

I want to know, In which format the Geographic data stored in geometry data type of SQLServer 2008.it looks like a long string,like 0xE6100010466DFEOA4089663524....... for one polygon. My second ...
0
votes
1answer
2k views

C# library for converting geom field of SQLServer into set of google latlng

Is there any C# library which can convert the geometry field into set of google latlngs? I have stored a shapefile into SQLserver table. From Sqlserver i want to read the geometry field data and want ...
2
votes
1answer
470 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 ...
10
votes
3answers
15k views

How to convert .shp to .csv including attributes AND geometry?

I have a .shp file with 60k+ entries, all of which are polygons with corresponding attributes (acreage totals, landowner names, tax ID #s, etc.). What I ultimately need is a .csv file with all of ...
6
votes
1answer
3k views

Geometry from multiple selected features into one geometry

Lets see if I can explain what I'm trying to do. First of all I have developed an AddIn for ArcMap that can take one selected feature (Polygon) on a layer, grab the geometry of that feature, and save ...
6
votes
2answers
776 views

Get shortest distance between two geometries in ArcPy

I'm using ArcPy and using a cursor to step through one polygon feature class. For each of these 'source' polygons, I am creating a SearchCursor to find all polygons in a second feature class that ...
3
votes
1answer
844 views

geometryType property of Vector Layers in OpenLayers

ORIGINAL: I have a couple questions that are focused around the geometryType property with vector layers. When you create a vector layer you can set the geometryType property to limit the geometry ...
1
vote
1answer
934 views

What is geometry datatype?

What are the basic that one should know about geometry datatype? How is it computed ? Why do we need geometry data type? Edit: I wanted to know why there is a different datatype called geometry. Is ...
10
votes
5answers
1k views

Measuring straightness of a curve segment (represented as a polyline)

I'm working on an automatic elevation contour labeling algorithm and one of the factors that I want to take into account when deciding the positions of labels is how "straight" a particular segment of ...
4
votes
0answers
244 views

Topology - To be, or not to be, that is the question [closed]

Topology, I mean "real" topology, is not a new concept and it's available since a long time in GRASS gis. I won't speculate the reasons myself but, after a long period of spaghetti model ...
1
vote
0answers
248 views

Problems with Multipatches

I have some polygonal features that have minimum and maximum z values. I'm trying to calculate the difference between a fixed extruded polygons and the sum of extruded related polygons. Here's how ...
5
votes
3answers
1k views

Any .NET library to calculate polygon area?

Is there a .NET library to calculate area enclosed by polygon made up of geo coordinates (lat longs)?
3
votes
2answers
704 views

How do I find the points of intersection between a small circle and a great circle?

I only actually need to intersect a great circle arc i.e. the shortest path between two points, with a given small circle. I found this tutorial for intersecting two great circle arcs, but ...
5
votes
1answer
252 views

Intermediate points on a small circle

I need to interpolate lat/lon points along a small circle, with a given centre and radius. I've successfully used these formulas for great circles. What is the equivalent for small circles?
3
votes
2answers
434 views

Determine point relation to given line

In ArcGIS engine I have a polyline with From and To points. I also have a Point. How can I determine if the point is located on the right or left of the line on the plane considering the direction of ...
1
vote
0answers
668 views

ArcGIS 10.0/arcpy: Can't retrieve the points in a polyline geometry obect: any idea why?

My arcpy script builds a Python dictionary, dictCLPnts, that holds the geometry objects of a polyline feature class. The following code snippet shows the attempt to access the geometry object with ...
4
votes
0answers
713 views

OpenLayers: WFS request to GeoServer to retrieve “name” & “featureNS”

Using WFSGetCapabilities I sent a GetCapabilities request to GeoServer. From the result of WFSGetCapabilities().read(), I can loop each featureType and retrieve some basic info(e.g., name, title, ...
3
votes
2answers
1k views

OpenLayers + Geoserver: how to dynamically retrieve the “geometryName” of a feature layer in GeoServer

I am trying to get the list of feature layers on GeoServer and then user can add layers into map at anytime they want. my question is: when using OpenLayers.Protocol.WFS loading a layer, is ...
4
votes
4answers
1k views

Is there a way to convert 3D polylines to 3D points in ArcGIS?

I need to convert a huge number of very dense (densified to 1m) 3D polylines to 3D points. I need each vertex along the line and no duplicates (two of the same XYZ coordinates) if possible. Is there ...
5
votes
5answers
1k views

Python, shapely library: is it possible to do an affine operation on shape polygon?

I am trying to create a rotated rectangle in lat/lon coordinates. Basically I have the coordinates of the center and rotation angle around the center. Is it possible to do using, shapely or gdal, or ...
26
votes
3answers
7k views

Visualising WKT geometry string in QGIS

A very simple question: Is there a simple tool in QGIS to graphically visualise geometry formatted as text? Example geometry: "POLYGON((571178 6337246,571178 6402217,598061 6402217,598061 ...
0
votes
1answer
2k views

Moving graphics in Esri Flex Feature Layer

I have an ESRI Flex 2.3 FeatureLayer with some graphics in it. I am able to access the graphics geometry and parse the geometry as Esris MapPoint class for Flex Api. I am calling the update(x,y,srs) ...
3
votes
1answer
367 views

Open dataset(s) with centroids or other geometry for WOEIDs?

The Yahoo! GeoPlanet data is available for download but this data only includes the object hierarchies without any associated geometry. Do anyone know if there is an open source for geometry ...
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
1answer
236 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
434 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 ...