(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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5
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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 ...
1
vote
1answer
103 views

Postgis invalid geometry from shape file

I'm having trouble converting a Feature class (shape file) to a DB table (Postgresql 8.4/Postgis 1.5). This is the command in the pg log: INSERT INTO "public"."distritos" ("Shape" , "DEPARTAMEN" , ...
2
votes
1answer
322 views

Reading OGC geometry data from SQL server using R

I would like to write a script in R that creates a map using OGC geometry data that is stored on a Microsoft SQL server. Is there a way to read OGC geometry data using a query passed from R? Maybe ...
3
votes
2answers
453 views

Visualize Spatial Data in Reporting Service

Is it possible to visualize a piece of geographical map from SQL server Spatial data (geometry, not geography) in a report from reporting service? If yes, how should it be done in a course of action. ...
6
votes
3answers
273 views

What geometric attributes do polygons possess, and how can these be used to filter features?

Given a polygon featureclass containing many polygons of different sizes and shapes, which geometric attributes (area, perimeter, etc) could be used to filter the polygons? It's probably best to ask ...
2
votes
1answer
401 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 ...
0
votes
2answers
250 views

Calculating area gets a different result

I've calculated the area of polygons with QGIS by using ctr-i - geometry - $area. I've set it on real. The results seem fine, but I've noticed they differ from the area given when I use the ...
2
votes
1answer
3k views

Make POINT from longitude/latitude coordinates from existing table in PostGIS

I would like to make a POINT using the longitude and latitude columns of an existing table. Here's a link to the documentation of ST_MakePoint. Here's my table: CREATE TABLE sysinst.bio ( oid ...
2
votes
1answer
458 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. ...
0
votes
0answers
63 views

How to populate polygon extents to an attribute table in QGIS

Is there a way to calculate the XMIN, YMIN, XMAX and YMAX of a polygon and write it to a field in an attribute table? The Geometry functions available in the Field Calculator are for points. ...
3
votes
1answer
420 views

Geometry Conversion Problem

How do I convert from an ESRI.ArcGIS.Geometry.IPoint to an ESRI.ArcGIS.Client.Graphic point object? In other words, I'm wanting to convert from an IGeometry to a runtime geometry, I guess.
3
votes
2answers
224 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 ...
3
votes
2answers
437 views

arcobjects update geometry Z values of line vertices with a given number

I am trying to develop arcgis 10.0 addin to update Z values of vertices of a selected line. Scenario: The tool scans all features in a given shape file and populates the list of features which has at ...
4
votes
2answers
328 views

PostGIS algorithm to unite points of two geometries that are within specified radius

I want to find an PostGIS algorithm to unite points of two geometries that are "near" to each other. That is: I want a function, that takes as input two geometries, and returns 1 geometry, that ...
2
votes
1answer
331 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 ...
1
vote
3answers
133 views

How to Retrieve X and Y from a papermap or gif picture

Goal: Visualize a subway map in SQL server 2012 spatial data based on the map of the subway. The map shall use geometry, traffic rail road as line object, station as point object and zon as polygon ...
1
vote
0answers
102 views

Geoprocessing operations re-introduce geometry errors after “repair geometry” succeeds

I am working with a shapefile that has many small, detailed polygons. After exporting it to a feature class in a geodatabase, I found that some operations (for example, Snap in the Editing Toolbox) ...
2
votes
2answers
530 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 ...
0
votes
1answer
481 views

how to find vertices for a geometry in OpenLayers

I am having a LineString, where I need to find the vertices logically and save those vertices. Can anyone help me out. Or else how below can help me. OpenLayers.Geometry.LineString = ...
2
votes
0answers
70 views

Critera for geometry or geography

What criteria do you need to take account to before you choose geometry or geography map? Is there a book or page about it?
1
vote
0answers
231 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 ...
2
votes
3answers
538 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 ...
3
votes
1answer
562 views

Join attributes by location

I am trying to join multiple records that occupy the same location (polygon centroid) and have tried using the join by location plug-in but have found this does not work for me in this case as I have ...
4
votes
1answer
457 views

How to find the nearest polygon from a given point?

Basically I have set of points [lat-long pairs] which defines different polygons on map. Now I have a coordinate [lat-long] from which I want to find the nearest polygon from that point. Any help ...
8
votes
2answers
1k views

Nearest point on a line ( Spherical / Mercator projection )

I have a line (Ax,Ay - Bx,By) over a mercator projection (google maps) and a random point (Cx,Cy) nearest to that line, i would to know the closest point (transparent blue on the image) over that line ...
5
votes
2answers
1k views

Calculating a spherical polygon centroid

I'd like a general way to calculate centroids for polygons on a sphere. So far, the best online reference appears to be: Tools for Graphics and Shapes by Jeff Jenness. The method described ...
5
votes
1answer
106 views

Should the geometry column always be the last column of a postgis table?

When we need to add an attribute to a table (e.g. a table of 350,000 polygons), my instinct is to always recreate the table so that the geometry column is last. I think this is a best practice for ...
8
votes
1answer
277 views

How to rank polylines according to their similarity to a ref polyline?

How to rank polylines according to their similarity to a ref polyline? Update 1: simulations show that simple $\sqrt{\sum{(case-ref)^2}}$ can find better similarity between polylines (as set of ...
1
vote
1answer
261 views

“There is not enough memory” Error when accessing IArea.LabelPoint

I have an intermittent error that I'm having a terrible time tracking down so I thought I'd see if anyone has encountered something similar. I am trying to access the label point of a polygon feature ...
5
votes
1answer
271 views

How do you fix Overlapping Lines?

I have a line dataset that contains some lines where the "end points" are actually found in the middle of the line. In the image below, the nodes are shown in green and one of the end points in red. ...
5
votes
1answer
642 views

Python: find a method to calculate the “inner centroid” (also known as labelPoint in arcmap) of a polygon

i am looking for a method to compute the X,Y coordinate of a inner point (also known as labelPoint in arcmap) of a (irregular) polygon. I am try to find a solution without the use of ArcGIS module ...
2
votes
1answer
2k 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 ...
1
vote
2answers
512 views

dealing with 2 different coordination systems in postGIS

I'm seeking a function that converts degrees to the following format: POINT(405115.926025391 4543389.4354248) I dont know this format's name, but is there any function to do so? Cheers, EDIT ...
3
votes
4answers
823 views

What is the easiest way to detect geometry type from text in PostGIS?

I have some records with different types of 'geometries (poly,line,points)' stored as string. I'm trying to use ST_GeomFromText as I want to do some intersection with them. What is the easiest way to ...
2
votes
1answer
331 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 ...
4
votes
1answer
170 views

Tunnel distance approximation

Having two points (longitude, latitude) on earth, if I am sure their distance is under 100 km; how much error will I have using tunnel distance approximation? (Defined at here) Note: Currently I am ...
3
votes
2answers
561 views

How to find self-intersecting polylines using ArcObjects?

If I have a polyline, how do I figure out whether it is self-intersecting? I tried to use ITopologicalOperator.IsSimple Property, but it always returns true. Are there any ways of doing these kind ...
3
votes
1answer
177 views

Road layers appearing as points in GeoServer previews - both openlayers and GeoExp

I am wondering why my roads layer keeps appearing as points when previewed inside GeoServer - layer preview using both the OpenLayers and GeoExplorer options. The data are imported from PostGIS. I ...
12
votes
4answers
1k views

How can one compare two geometries in arcpy successfully?

I am trying to compare two separate feature classes to identify differences between them (sort of a diff function). My basic workflow: I extract the geometries using a SearchCursor Save the ...
1
vote
1answer
511 views

How to add constraints in PostGIS?

I have table that containing road network. Table structure is CREATE TABLE final_all_india_road_network ( gid serial NOT NULL, "name" character varying(254), code character varying(254), ...
5
votes
1answer
722 views

How to split a Polyline Geometry at a certain point in ArcObjects?

I have a polyline geometry and wish to split it into two different geometries, based on a given point on that line, in ArcObjects. I have tried to find out how to do this, but to no avail. I found ...
1
vote
0answers
92 views

Calculating spaces between roads from PostGIS database

Is it possible to calculate the spaces between the roads using a select statement in a PostGIS/PostGre Database? I tried using some combinations of the predefined functions as ST_Intersects & ...
1
vote
1answer
328 views

ESRI android SDK Calculate area in square meters from polygon geometry

Hello I have a Polygon object in ESRI Android SDK that I'm creating on a map, I would like to calculate that polygon object to square meters. currently I use double area=polygon.calculateArea2D(); ...
3
votes
1answer
341 views

Limit Zooming Geometry Features in OpenLayers

I draw flag feature on my map as follows: myVectorLayer = new OpenLayers.Layer.Vector("Flag Geometry", { renderers: renderer, isBaseLayer: true, projection: new OpenLayers.Projection("EPSG:900913"), ...
3
votes
2answers
498 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 ...
3
votes
1answer
354 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 ...
1
vote
3answers
586 views

In ArcMap, what is the difference between Copy Parallel and Buffer?

To build an offset of a linear feature in ArcMap, what is the difference between Copy Parallel and Buffer? In terms of the resulting features and their linear differences from the source linear ...
4
votes
2answers
3k views

How to repair topology of a shapefile?

I performed an object-based image analysis using ENVI EX, and each of the classified features were exported as a shapefile. I transferred those shapefiles into ArcMap 10, and tried to intersect them ...
5
votes
1answer
180 views

How can I increase performance on inserting features with polygon geometry?

I have a problem when inserting features with polygon feature class in FGDB. This is my code: ... initialising some fields (does not affect performance) m_featureBuffer.Shape = ...
0
votes
1answer
650 views

ArcGIS/arcpy: Can a variable be set to reference an in_memory workspace object?

This is an offshoot question related to a question I posted earlier. I have the following arcpy code that inputs a Python list of polygon geometry objects to the Union_analysis tool, which then ...