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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1answer
139 views

Performance Improvement of Postgres vs PostGIS

I am trying to run the following query thousands of times per second to determine which is any polygon contains the passed in point. SELECT * from areas WHERE poly @> ? Poly is the name of the ...
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2answers
159 views

Maximum distance to polygon edge

I have a point feature class and a polygon feature class, and each point is located within one polygon. Is there a way to programmatically calculate the distance from each point to the farthest ...
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1answer
267 views

Remove lines from inside a polygon in QGIS

Through a "dissolve" process in QGIS, I achieved some polygons that have some fails, like this one in the screeshot: Is there any automatic process I can make in QGIS to remove those lines inside ...
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1answer
74 views

Edit raster classification manually using polygons - ArcMap

I want to edit the elevation/z values of certain zones on a raster in ArcMap. I followed this example by creating a polygon, assigning a value of 7.5, then converting the polygon to a raster, finally ...
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1answer
142 views

FeatureToPolygon (to cut polygons by line) not working correctly outside of ArcGIS

I asked a question yesterday, about splitting polygons using a line, and I ended up using the approach that is described in the comments here. Although this worked with my test data, it causes a lot ...
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1answer
168 views

How to get the coordinates inside the polygon using python

I have a polygon and using this code snippet we can get the coordinates boundary of the polygon. canvas = qgis.utils.iface.mapCanvas() aLayer = canvas.currentLayer() coord = ...
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1answer
163 views

ST_Intersection for polygons

I'm looking for a query that returns overlapping areas of two tables with polygon geometries. Using row_number() over() the entries of the gid column are not unique in the case of dumped ...
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1answer
180 views

How to get a “clean” polygon after using dissolve in QGIS?

I'm trying to obtain the boundaries of shapefile, thus to clean the inside as a matter of speaking. While I had expected that dissolve while get me a proper polygon, unfortunately it still has some ...
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2answers
44 views

add polygon to layer from text file [closed]

I am completely new to Qgis and to gis in general. I have start to work my way through the documentation but have a question that I can not find a answer to. When looking into the documentation ...
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1answer
125 views

Connecting polygon accidentally deleted - filling in the gap

New QGIS user, Brighton 2.6. I accidentally deleted an elongated (lots of "peninsulas" polygon that represents a stream-based habitat - two gaps on SW boundary and two on the northern boundary ...
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1answer
79 views

Is there any way to know if a polygon is part of another bigger polygon(s) in SQL server?

Basicaly, what I am trying to do is we have a lot of geographical containers like territories, sub-territories etc. and the boundaries of each keep on changing all the times and I have to store the ...
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1answer
1k views

Overlapping polygons in the same layer

I am working in QGIS on a vector layer where areas are classified using an attribute "typo". The problem I'm encountering is that many polygons are duplicated or overlapping, with the result that some ...
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2answers
217 views

How to separate polygons within layer and measure line through each polygon?

I have 3 layers of polygons, each layer with multiple polygons spatially separated, although the layer only counts it as 1 polygon. I have a layer with a line going through these polygons. What is ...
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1answer
188 views

Cover a polygon with fixed size squares

Can you please advice me of an algorithm (which I can implement in a Java) to cover some polygon (not exact cover) with squares of certain size (aXa squares)? The cover doesn't have to be exact - ...
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1answer
158 views

CartoCSS: labels along inside of polygon boundary

I'm using CartoCSS to render maps that include large polygons (like national parks). At higher zoom levels I want labels along the inside of the polygon boundaries, like in OpenStreetMap: I ...
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1answer
338 views

Why does one polygon disappear when merging in edit mode?

I want to merge some polygons into one using the merge tool. But when doing so, one of the polygons just disappears (see screenshot 2). Why does this happen? When I use the simplify tool before, it ...
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1answer
267 views

How to clear areas outside map in R

I succeeded thanks to the eblonde in the disscution (problem with polygon smoothing in R) to smoothing polygons in R. Code: inter1= read.table("c:/inter2.csv", header=TRUE) #add a category ...
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1answer
107 views

Looking for information on methods or algorithms used to calculate centroid from polygons across software

Looking for information on methods or algorithms used to calculate point centroids from polygons across software. ArcGIS uses a "gravity model" but can someone point me to the math or a paper on the ...
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1answer
123 views

Converting rasters to polygons through cell centers

With arcgis, it is possible to convert a raster image to a polygon representing the boundary of the raster using the Raster To Polygon tool. The output polygon will follow the cell edges of the ...
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1answer
148 views

Snapping with polgon drawing

I am drawing a polygon with the drawing function within ArcGIS 10.1. Is there a way to snap orthographically at 90 degrees while using the polygon draw command. I added a picture of what i would ...
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2answers
426 views

QGIS Convert Polygon M to polygon

I have been using Argis 10.1 and been able to convert polygon m to polygon shapefiles. I would like to do this with QGIS but I am having difficulty in finding the correct tool to do so. Please Help
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1answer
252 views

Calculating distance of polygons from coastline using ArcGIS for Desktop?

I have a series of polygons representing parcels of land. I would like to calculate the distance of each polygon from the coastline. I also have a polygon of the entire region of interest, i.e. an ...
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1answer
579 views

Calculating percentage of polygons within specific areas using ArcGIS for Desktop? [closed]

I have a parcel layer and I am trying to determine the percentage of each parcel that falls within specific zones. I tried tabular intersect but it just returned an empty output. I'm using ArcGIS ...
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1answer
164 views

How to compare multiple spatial point patterns over a polygon

I have multiple point pattern distributions over the same region/polygon. Each point pattern distribution has different number of points. Here is an example of two spatial point patterns for the ...
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1answer
602 views

Intersect between polygonal shapefiles error

I'm encountering a problem when I try to intersect two different shapefiles. They are all new shapefiles I created to descibe the land cover and the land use of a city. The problem occurs when I ...
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1answer
570 views

How to limit Create Fishnet extent by mask & carry over attributes?

I have a 5km polygon grid of an area which is not a standard square/rectangle, it is in fact a rough ovoid made up of around 500 5km2 cells. What I want to do, eventually, is have a 100m polygon ...
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1answer
1k views

How to go with…somewhat complex geological maps in QGIS?

Just a follow-up to this question QGIS: Line to polygon conversion. Not sure do i have to continue there itself... We are currently digitizing a geological map...which has 36 features in total. Some ...
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1answer
511 views

Eliminate 0 Values From Raster

Arcgis 10.2 I currently have a raster file that I want to turn into a set of polygons. This will help me to create specific buffers around certain points. The extent of my values are 0, and 1. When I ...
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1answer
388 views

How to generate random GeoJSON polygons (latitude, longitude)

I am looking how to generate polygons in GeoJSON format with random locations (latitude, longitude), if I generate totally random set of points it will not produce valid polygons. So my question is ...
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1answer
164 views

How do I add coordinates to a polygon layer to be able to sort the polygons from north to south in QGIS?

I have a polygon file, where each polygon represents one property. I want to be able to sort the polygons from north to south or vice versa. I need them to be sorted in this way when I export them to ...
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2answers
968 views

How to change raster cell values within a polygon using QGIS GUI?

I would like to know how to change the values of raster cells which are within a polygon, leaving all cell values outside the polygon unchanged. I would like to subtract 1.5m from each raster cell ...
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1answer
146 views

draw multipart polygon with one surrounding border

As you can see on the image below, the waterbody is divided by the border line because it consists of several polygons. I could merge the polygon, but I dont want to change the shapefile. Is there ...
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2answers
332 views

How to extract common outline of multiple polygons with code?

I'm not really asking for a chunk of code to do this, but more of an algorithm I can work with myself. For example, this is the state of Maine, obviously, and I have the points of each county ...
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2answers
471 views

Calculating minimum/maximum width for overlay of two polygon strips in ArcGIS or some Opensource GIS

Is there some solution for calculating minimum and maximum width for overlay of two polygon strips? When I clip these strips the result is another strip with variable width about 1 km and 20 km long. ...
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3answers
903 views

“Identity” overlay in QGIS?

I have two polygon layers I'd like to overlay using QGIS or another open source tool. What I want as output is a polygon layer with the extent of one polygon, but with each polygon in that layer ...
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1answer
670 views

JTS Polygon simplification without holes

I have a set of polygons without holes. I wish to merge any intersecting polygons. I don't want to have any holes in my simplified polygons. Is there a recommended way to achieve this using JTS? The ...
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1answer
2k views

Get Features from OpenLayers Layer.Vector not working

polygon_layer = new OpenLayers.Layer.Vector("Polygone", { projection : projLonLat, strategies : [ new OpenLayers.Strategy.Fixed() ], protocol : new ...
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1answer
194 views

How to count number of stores per company per region?

I have two layers. One point layer and a Polygon layer. It is simple to count the points in the polygon layer by the "points in polygon" function. But I also need some more information of the point ...
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1answer
2k 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 ...
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3answers
1k 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; ...
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1answer
149 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 ...
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1answer
366 views

Sum of point attributes inside hexagons using QgiS UI

I'm very new to Qgis so I would very much appreciate any help you can give me. I have a point shapefile that corresponds to locations of animals captured. I've joined a table to this shapefile with ...
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2answers
716 views

Where to find the variables of QgsPolygon and QgsPolyline?

now I want to use QgsPolygon (and Qgspolyline,too) class in python I have a example by using QgsPoint but I don't know how to use in QgsPolygon following is my Qgspoint example feature = ...
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2answers
2k views

How to convert self intersecting polygon to multipolygon?

Working with the union and polygonize methods in GDAL/OGR, I often end up with self intersecting polygons. The case is one polygon which essentially consists of two polygons: In the above example, ...
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1answer
173 views

Polygon Nodes do not have separate coordinates [duplicate]

I'm attempting to measure the distance of a series of points from a smaller number of polygons. As a first step, I've changed the polygons into points along their border, via the Vector> Geometry ...
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1answer
619 views

Aggregate points with same values to polygons

I have a shapefile with 2M measurement points (each measurement point has a resolution of a 1/10). How can I aggregate points around each other if and create polygons out of it? They do not have to ...
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1answer
136 views

Split polygons and extract points

I have a polygon file with 90 adjacent polygons. I also have a lat/long point file that overlaps the entire surface of the polygon file (170,000 points). My problem is that working with all of the ...
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3answers
836 views

How to create one KML per polygon (from one Shapefile)?

I have a shapefile containing hundreds of polygons. I need to create a kml of each of the polygon. Is there any way that I may not have to deal each polygon individually and my polygon file may give ...
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2answers
2k views

One Polygon Joining to Database with Many matching records

Using ArcMap 10.1. Is this possible to have one polygon and join to a database/excel with many matching records? I would like to have 1 polygon but match to 100 corresponding records in a table. When ...
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1answer
405 views

Updating Polygon Geometries in master shapefile with detailed boundaries using ArcGIS Desktop?

I have a shapefile which contains the approximate boundaries for sites that are being worked on (thousands) in polygons, each with a reference number and additional detail in the attribution. I have ...