(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
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
650 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
514 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 ...
8
votes
4answers
11k views

How to get coordinates from geometry in PostGIS?

This line: SELECT geom FROM myLayer.geom will return a hex value, i'm wondering how would it be possible to get decimal values, a result that look likes human-readable coordination? Regards,
3
votes
4answers
849 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 ...
4
votes
1answer
171 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 ...
2
votes
0answers
156 views

how to convert lat and longitude into distance near poles?

I am trying to convert latitude and longitude into meters in polar regions. I am looking for higher accuracy upto 0.00 meters preferably. I tried the haversine formula but it doesnt seem to be ...
21
votes
1answer
674 views

Space filling between random 2D lines

Consider a region (2D) filled with lines randomly (following Figure). We are interested in filling the empty spaces between lines including four boundary edges in a way: 0- maximizing the size of ...
3
votes
2answers
564 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 ...
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 ...
3
votes
1answer
178 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 ...
2
votes
1answer
335 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 ...
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 ...
11
votes
3answers
1k views

Self intersections for polygons, how to solve?

I have a question about repairing a self intersecting polygon shapefile. I have a shapefile containing Polygons (ZM) which have self intersecting features. If I use the "repair geometry" tool, it ...
5
votes
1answer
727 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 & ...
3
votes
1answer
345 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"), ...
1
vote
1answer
518 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), ...
1
vote
0answers
278 views

ArcGIS/arcpy: Geometry object comparison methods not working. Do they take z values into account?

I have an arcpy script that makes calculations based on an input PolygonZ feature class. What I need to do in several places in the script is test whether a point falls within a polygon in 2D. In ...
3
votes
2answers
503 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 ...
1
vote
3answers
595 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 ...
1
vote
1answer
331 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(); ...
2
votes
2answers
536 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 ...
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
656 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 ...
0
votes
1answer
858 views

ArcGIS/arcpy: Input of in-memory geometry object to Dissolve tool in arcpy script throws Error 000732, input doesn't exist or is not supported

In an arcpy script, I run a Union on a list of geometry objects. The output is set to an empty geometry object. The Union runs fine. What I am trying to do is then feed that output into the ...
1
vote
1answer
711 views

PostGIS and geometry column

I have a csv table. Each record includes a start node (lat1,lon1) and an end node (lat2,lon2). I have already imported the .csv into Postgresql 8.4. Now I would like set the geometry column. I tried ...
5
votes
2answers
555 views

IFeatureClass.Search throws error “0x80041599 The number of points is less than required for feature”

I am creating a buffered geometry around a point feature in order to search for other nearby features. I use the TopologicalOperator to create my buffered geometry. I am attempting to search a feature ...
3
votes
1answer
214 views

Splitting large PostGIS/GeoServer geometry for WMS optmization

I have a large geometry (MultiPolygon) for a (fictional) world map. It basically spans a large portion of the entire world: it's the difference between a buffered extension of the union of the entire ...
2
votes
3answers
2k 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 ...
0
votes
0answers
21 views

World country borders in polygon geometry format [duplicate]

Possible Duplicate: Where do I get territories data? Is there some source I can get all world countries polygon geometry points with latitude and longitude? I find it for USA states but ...
0
votes
1answer
39 views

Requires Datatype for inserting features

I have imported postgis data in geoserver. In geoserver the spatial data column is displayed as MultiLineString, Does it affect when inserting features into geoserver or does it have to be explicitly ...
4
votes
2answers
774 views

Why are self-intersecting polygons bad?

Working with both ArcGIS and Oracle Spatial, a self-intersecting polygon renders a geometry invalid. Why are self-intersecting polygons a problem?
4
votes
2answers
128 views

How can I dismantle and reassemble a polyline by joining each point to its nearest neighboring point?

How can I reconfigure a PolylineMZ feature class in a way as shown in the image below? I have a feature class (PolylineMZ) which contains x-sections. Some x-sections (polylines) are badly constructed ...
12
votes
2answers
3k views

Correcting gaps and overlapping polygon (parcels) geometry

I have come across a resource that we rely upon almost daily that is in terrible need of repair. It is not our own product and the supplier is generally not interested in fixing the problem. We are ...
7
votes
2answers
738 views

Growing a PostGIS geometry by a percentage

I'm looking for a way to add a buffer around a PostGIS geometry, but the size of the buffer should depend on size of the geometry. That is, I want each geometry to be enlargened by, say, 5%. The idea ...
0
votes
2answers
711 views

How can I convert Polygon to LinearRing Geometry?

How can one convert a Polygon to LinearRing geometry using OpenLayers? I'm thinking that I can do this by getting bounds of the polygon, then use this to construct a Points array. Finally, use ...
5
votes
1answer
399 views

What is the unit of measurement for buffer calculation?

What is the unit of measurement used by Geometry class for it's buffer calculation ? Api doc currently defines it as " distance - the width of the buffer (may be positive, negative or 0)" I need to ...
4
votes
2answers
1k views

How to update geometry in ArcObjects?

I'm just starting with ArcObjects and I want to update coordinates of geometry vertices. Specifically, I want to swap X, Y coordinates for each vertex of polygons (which can be multipart and have ...
0
votes
3answers
3k views

Get geometry from coordinates

I have a table with geometry column called point, saved in SRID 4326. I want to get the geometry by its coordinates, but something didn't work. I suspect database configuration or something. Here is ...
0
votes
1answer
100 views

create geometry in arcpad

i want to create a point geometry in ArcPad 10 VBScript, to make custom feature drawing. so i want create point geometry then record.shape = point or records.AddNew(point) i want to create ...
0
votes
2answers
1k views

Calculating shape perimeter/area per zone in ArcGis 10

How can I calculate geometrical features of polygon (perimeter and area) per zone (similar to zonal stats for rasters)? I have a square fishnet (approx 20x35, 1 square kilometer each) and I need to ...
5
votes
1answer
889 views

fTools-Error: “…invalid geometry…”

I want to intersect contours with polygon like in the image below. But i got this error: Warnings: GEOS geoprocessing error: One or more input features have invalid geometry. Some output geometries ...
1
vote
1answer
333 views

Calculate MBR envelope for different geometry shapes in different rows

I have some different kinds of geometry (Polygons and line strings) stored in my mysql database. On different rows. I know I can retrieve the envelope of one row with: SELECT Envelope(zoneShape) FROM ...
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 ...
6
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
312 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
888 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 ...