On a map, a closed shape defined by a connected sequence of x,y coordinate pairs, where the first and last coordinate pair are the same and all other pairs are unique.

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2answers
300 views

how to set width & height of a polygon in QGIS

I can't setting width and height of a polygon How to do that in QGIS? Thank you
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0answers
279 views

Export topology tables to txt files using ArcObjects, generating directed graph, and finding intersections

I want to export topology tables to text files: for points: 1 id x y for lines: line id fompoint.x from point.y topoint.x topoint.y for polygons: id line id 1, line id 2... 2 arc ...
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2answers
992 views

How many interior and exterior rings can a polygon have in a standard ArcGIS shapefile?

working with GDAL/OGR library and studying these two slides about geometries and vector data in the OGR library: slide 1 slide 2 I found that a polygon can have an exterior ring and lots of ...
6
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0answers
171 views

Find and destroy duplicate OSM multipolygon/polygons in TileMill/PostGIS

In OpenStreetMap there are sometimes multipolygons where attributes are present on both the polygon and the multipolygon relation, such as the Grampians National Park: ...
0
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2answers
943 views

Detecting invalid polygons (self-intersecting or touching)

An invalid polygon can be defined as one that intersects itself, or one where the lines make contact, ie, the two shapes at the top of this picture. Given the XYPoints of a polygon, what logic ...
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0answers
102 views

level of spatial aggregation of polygons

I am looking for a method that allows me to obtain the spatial aggregation of polygons for each cell of a grid with 10kmx10km resolution. In each cell (10kmx10km), I want to be able to consider that ...
2
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2answers
608 views

Finding points along a path

I am unsure of the best approach to this problem. I can think of some ways of doing it which I will list below but I am looking for the best and most efficient way of doing this. Problem Given a ...
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0answers
202 views

Divide polygon based on points for even distribution

If I have a point layer, how can I create a polygon that includes all of the points and divide that polygon into n sections in which each section contains an equal number of points? Preferably in ...
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1answer
176 views

How to get average polygon? [duplicate]

Is there a way to get an average polygon of unioned stack of polygons in ArcGIS 10.0? I would like to get an average polygon that would be centroid (but polygon) of whole stack of polygons.
0
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1answer
58 views

represent multiple geometry as single feature

There is a school. it is on two disjoint areas, one is primary wing and other is secondary. I need to make single feature from the two areas such that, there is only one column in gis table, i.e. only ...
1
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1answer
579 views

Polygon to raster without losing any polygons

I'm trying to convert polygons to raster. But the output raster dataset doesn't have polygons which went into as input data. I need all the date in the attribute to follow with to the raster dataset ...
0
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1answer
143 views

How to send polygon data to wms?

I use OpenLayers and GeoServer. I can read kml file format from OpenLayers. And I want to edit this polygon in kml. So I want polygon data(polygon circle and center coordinate etc..) to GeoServer.
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1answer
353 views

How to convert OSM polyline data to polygons?

I just now downloaded OSM data .I am having the data as polylines. I want that polylines as polygons is it possible in Qgis?below I also posted the screen shot of the polyline also.
3
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2answers
660 views

How to do a Point to Polygon analysis with multiple variables?

I have a database of almost 10k crimes, which are divided in to 10 categories and plotted on a map I also have a database of 12k addresses, which are also plotted on the map. I aim to perform a ...
0
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2answers
519 views

ArcGIS 10.1 - Using Polygon Neighbors with dissolved polygons

I've used polygon neighbors to find all neighbors of a polygon layer, which I then use to look up all possible neighbor combinations and dissolve the polygons into all possible combinations of two ...
1
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3answers
811 views

How to change feature color?

I have feature (polygon) was gotten by spatial query from the map. How to change its color? I used this code but it didn't work IMxDocument mxDocument = application.Document as IMxDocument; ...
3
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0answers
111 views

Reshaping polygons while preserving area

I'm looking to manually skew the shapes of areal polygons, but need to ensure their areas are not altered. Is anyone aware of any GIS tools or programming workflows that exist for manually reshaping ...
1
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1answer
199 views

Aggregating a raster to fit a polygon grid

I am working at the scale of 10 square km grid cells for the UK, and have a polygon layer of the Ordnance Survey 10k grid cells in ArcGIS. I have another layer of the human footprint index, also for ...
1
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0answers
107 views

how to avoid Intersection of polygons via python code

i am using QGIS 1.8 and i can set the check box in Setting\Snapping Options "Snapping and Digitizing " dialog to avoid polygon intersections and enable topological editing but i am looking for a way ...
0
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1answer
70 views

Polygons Shrinking and Moving as if CRS Was Suddenly Out of Sync with Project

I long ago set the CRS for a linguistic geography project I'm working on involving Oklahoma data (EPSG:2836 - NAD83(HARN) / Oklahoma North), and I have been closely monitoring that the polygon ...
1
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1answer
1k views

How do I write a MYSQL spatial query to find all polygons (rectangle) that contain any points in a table?

Something like: SELECT * from polygons WHERE bounds CONTAINS(SELECT geom_point from points) Can someone help me out with the syntax? Bounds will always be a rectangular polygon and everything is in ...
0
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1answer
89 views

Converting an Experian (Geoconcept) file to GPS coordinates

I'm working with a file containing Experian data which was used in Geoconcept. The file describes a serie of microzones, that is polygons. Unfortuntely the coordinates system is hard to understand: ...
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0answers
113 views

How to convert a set of points to a polygon based on a specific field in QGIS

I am having a point shapefile that consists of a number of point sets. I need to convert these points to a polygon based on a particular field in attribute table say for example locality . How can i ...
0
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1answer
4k views

How to create polygon with DBGeography Class in Csharp

I want to create a polygon with csharp 4.5 via DBGeometry class. I found example on csharp to create a point via System.Data.Spatial namespace. (Requires Reference System.Data.Entity) This code is ...
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1answer
155 views

Union of polygons doesn't work 100 % correctly

I'm using the function gUnaryUnion to merge polygons in R. In one particuliar case this doesn't work correctly - some of the old polygon contours are still visible: Can anybody help ?
17
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2answers
5k views

How can I find a point inside a polygon in PostGIS?

How can I find a point that is guaranteed to be within a given polygon in PostGIS? I am aware of the ST_Centroid function. However, the centroid is not always within a polygon, see below: ...
5
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2answers
2k views

Tips for minimizing shapefile size without compromising geographical detail?

I work for a state government's fisheries service, and lately we've been digitizing a lot of our regulatory boundaries within the state's waters that we'd like to service out on web maps. ...
4
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2answers
717 views

How do I find the average distance within a polygon to a point?

For my purposes, I can assume a homogeneous distribution of points within the polygon. What I want to find is the average distance from points within a polygon to a specified point. I don't know where ...
0
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0answers
1k views

How to split polygons based on other polygons?

In ArcGIS, I have a layer of polygons (created from the Service Area function) and want to split each one of those based on another polygon layer (the boroughs of London). The purpose is that I want ...
3
votes
2answers
261 views

Detecting ring direction of a polygon using ArcPy

I am using ArcPy in ArcGIS 10.1 to process some geometry using the arcpy.da data access module. However I have run into a problem with complex Polygons that contain inner rings/holes. From the ...
1
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0answers
482 views

How to Smooth Polygons after converting DEM using Raster to Polygon?

I have a DEM SRTM that I classify using Spatial Analyst Tools > Reclass > Reclassify. The result is box shaped so I go to Layer Properties > Display and choose cubic convolution. The result is ...
2
votes
1answer
1k views

combine raster and polygon values in R

My question is similar to this one Get Raster Values from a Polygon Overlay in Opensource GIS Solutions but I think I need another step. I have a polygon layer of ecoregions which I brought into R ...
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2answers
537 views

Retrieve common paths of polylines ArcObjects

I have a polygon featureClass and a polyline featureClass. I now want to handle all geometries within the latter that are contained in the boundaries of polygon features, that means they shell simply ...
1
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1answer
102 views

Move shared vertices together

I should move some vertices of a polygon to fix the boundaries of a country, how can I do it while keeping the adjacent polygons still connected? Is there a way to anchor permanently overlapped ...
1
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1answer
1k views

How to find the intersection point of polygon geometry and multilinestring geometry in postgis

I have a polygon geometry and multilinestring geometry. How do i find the intersection of both these geometries. Both the geometries are in same reference system. Does st_intersection gives me the ...
2
votes
1answer
705 views

Distance of points in polygon to nearest polygon edge

I have a polygon shapefile with about a dozen polygons (Area.shp). I have an equation that calculates a value for points (or small areas) as a function of distance to the edge of these polygons. I ...
2
votes
2answers
2k views

Percentage of polygon in one shapefile within polygon of another

I'm a newbie, apologies if this is obvious/has already been asked and answered but I couldn't find anything. I have two shapefiles: 1. an administrative boundary layer for a county in the UK known as ...
1
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0answers
66 views

How to measure area of polygons generated from gps data in qgis? [duplicate]

Somebody classified my question as a duplicate. But applying the answer doesn't work for me. Here is what I did: - I made sure that my layer is in a projected coordinate system (UTM30N, WGS84) - I ...
0
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0answers
126 views

How to create sector figure in ArcObject?

How to create sector in ArcObject 10.1? Now I draw one point, two lines, two arks. But I think it is not good. It is differents objects. I need one object. Well. Now I drawing: IElementCollection ...
1
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0answers
248 views

Divide polygon evenly based on lines and intersection points

I have this purple polygon illustrated in the figure below. I would like to split the polygon so that each line segment (green) split the polygon evenly with the surrounding line segments. A line ...
0
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0answers
77 views

Unwanted lines when cutting & merging polygons

I am using QGIS version 1.8.0. Sometimes when I cut or merge polygons I get unwanted lines left in them. On zooming in to them they do not appear to be slivers. Is there a way of getting rid of these ...
0
votes
1answer
163 views

QGIS create point data attribute as the name of the polygon it falls in

I'm working in QGIS with a point data set overlaying a farm with 140 fields. While I can analyse the points from each field individually, I would rather use an awk script to calculate statistics I ...
6
votes
1answer
1k views

Identify polygon overlaps within single shapefile

Using either QGIS (1.9) or ArcInfo (9.3.1) I'm trying to identify unique overlaps of prehistoric building footprints from an archaeological site recorded within a single polygon shapefile. While the ...
0
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1answer
77 views

How can I know the number of polygons in a selected area in QGIS

How can I know the number of polygons in a selected area in QGIS? Can I use the Select features tool? How can I use? Thank you
4
votes
1answer
1k views

How to add CSV data with no coordinates to a polygon layer in QGIS?

I would like to add attributes from an spss database (around 300 cases) to a polygon layer in QGIS. Both datasets have a column with unique IDs. I exported the spss data to a CSV file which does not ...
0
votes
1answer
100 views

Can this compilation and display of species frequency data be improved? QGIS 1.8.0

As a newbie on QGIS, I would like to find out if the way I put a species frequency map together could be improved upon. I had to map the presence or absence of 7 plant species surveyed in 30 2m x 2m ...
0
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4answers
187 views

How can I calculate different polygons by different attributes?

I'm doing my master thesis and want to calculate different polygons (in QGIS 1.8 for Mac) in four different columns which I defined by different attributes. i.e. some of the attributes in the first ...
0
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0answers
80 views

Tiles cover Polygon on zoom and move

i'm using OpenLayers.Geometry.Polygon.createRegularPolygon to generate some nice circles. After i draw them to the Map i'm Moving them and after some while they where hiding by some tiles. The circle ...
0
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1answer
323 views

How to find and quantify duplicate vertices on a polygon/polyline in ArcGIS 10.0

I need to clean up topological errors in various shapefiles and databases. I did read that the Repair Geometry tool could clean duplicate vertices but how can I know the number of errors before and ...
5
votes
4answers
675 views

How to computational efficiently check if there are any overlapping polygons in a group of polygons?

I need to do some processing with groups of polygons. If any of the polygons in the group overlaps other polygon the result is unpredictable and don't throw any error. So, I need to detect if there is ...