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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6
votes
3answers
1k views

Can Polygons be generalized to MultiPolygons in GeoDjango?

I set up a model with models.PolygonField in geodjango, using postgres as database. I try to import shp into postgres. The problem is, shp (compiled with QGIS) mixes polygon and multipolygon, hence it ...
2
votes
1answer
120 views

Determine when I have crossed state line?

We are currently using the Google Maps API to get route information and total mileage but we would like to determine when we are crossing into a new state. When we return the route information we can ...
1
vote
1answer
15 views

Area of an EPSG 27700 polygon

I am working with EPSG 27700 polygon data in PHP. All the polygons are in the UK. The polygons do not have holes inside them. I'm hoping to be able to calculate the area of these polygons. For this I ...
1
vote
1answer
26 views

A library to edit geometry in C#

For my windows application, I am looking for a method to edit vertexes and geometry of features that are stored in a SQL Server database. I just want a simple function for dividing polygons into 3 ...
4
votes
1answer
166 views

POSTGIS SQL - How do I remove (defined) sliver polygons

I would like assistance in writing SQL (for POSTGIS in postgresql) to remove sliver polygons (including long narrow slivers and some small irregular polygons that were erroneous 'gaps' in the original ...
1
vote
2answers
93 views

Making single polygons from a shapefile

I created a shape file a while ago with several (20+ polygons) in it. I was wondering if there is a way to symbolize these polygons with unique symbols. Basically all I actually want to do is color ...
0
votes
1answer
245 views

How to calculate the percentage of distribution in each polygon?

I have binary map for disease suitable area and I want to calculate the percentage using pixel count in each polygon how can I do that? I use zonal histogram and do have frequency for each polygon is ...
3
votes
1answer
55 views

How do I save a polygon once I have created it in editor?

I am attempting to create a new polygon. I go to ArcCatolog>New>Shapefile and make sure Feature type is set to polygon. I create the polygon and if I click save edits or stop editing, it disappears. ...
1
vote
1answer
86 views

QGIS: Clipping a line layer using a polygon and getting an empty shapefile

I am using QGIS 2.2.0 and want to clip a line layer (roads) so that only those inside a polygon are shown. When I do this using Vector->Geoprocessing Tools->Clip I only get an empty shapefile as an ...
0
votes
1answer
343 views

Reverse geocoding polygon co-ordinates?

I have a large dataset of polygons for property sections that I need to reverse geocode. It was recommended that I use a GIS like Quantam to do this however from my research I am not 100% sure if a ...
1
vote
2answers
31 views

Adding polygons from an existing layer to a new layer (shapefile)?

I have an existing shapefile that contains parcel data. I would like to add some of the existing parcels to a new shapefile. I am using ArcMap 10.1.
5
votes
2answers
2k views

Converting Longitude and Latitude Coordinates to Square Miles?

I have a set of Long and Lat co-ordinates making up a five point polygon which I have converted in excel using the following formula: ...
-2
votes
0answers
24 views

OVERLAYING CURRENT INFO WITH PRIOR INFO OR INTEGRATING THEM ..hOMESTEAD RESTORATION pROJECT [closed]

WHAT SYSTEM OR APPLICATION TO USE FOR 3 OVERLAYS ON EXISTING MAP OF AN ADDRESS PURPOSE IS SHOW CURRENT SURFACE SLOPES OF A GROUND OR SURFACE LOCATION RESTORE WATERWAYS FOLLOWING NATURAL PATHS
3
votes
1answer
165 views

digitizing (tolerence) error in line data

I have designed a large number of boundaries. For accuracy, I took lines in patches from different data sets and merged them into one. Now I want to turn them into polygons from lines. I every second ...
1
vote
1answer
17 views

QGIS create raster from cadastre (property lot data) polygon

I have a cadastre (property lots) polygon dataset of a region. Have used rule-base style in QGIS to show different groups of properties in the dataset classified based on their property lot size (ie. ...
1
vote
1answer
125 views

Calculate distances between polygon centres in QGIS

Is there a practical way to calculate distances between polygon centroids in QGIS? I have a UK city region map divided into administrative units (1 ward = 1 polygon). I want to represent their ...
2
votes
1answer
38 views

Delete duplicate polygon nodes with PostGIS

I'm trying to delete duplicate nodes from a shapefile with QGIS, but after running the tool to delete it, nothing happens and shows the same errors. I thought that maybe importing to postgis could be ...
0
votes
1answer
25 views

Drawing outline of points in ArcGIS for Desktop [closed]

Simple question, can Arc take a shapefile of points, calculate which ones are at the "edges" and draw a polygon or polyline around it. I know there are masks and bounding geometry and all of that, but ...
1
vote
1answer
33 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 ...
3
votes
2answers
86 views

Remove Holes Existing Within a Single Polygon for a specific area in Qgis

I have a shapefile that consists of a single polygon. I have gaps within the polygon that needs to be eliminated, but only the ones that are less than 200m2. I tried different ways but none of them ...
3
votes
2answers
101 views

Add rectangle polygon

I have a polygon shapefile layer. I want to add a rectangle polygon (just like in Arcmap), and another one using the previous polygon edge. I need it to be accurate, my hands do not meet this ...
-3
votes
1answer
63 views

Extracting Cities, Towns and Villages boundary coordinates [closed]

How can I extract the polygon coordinates of cities,towns and villages from OpenStreetMap? Are there any other free databases available?
0
votes
1answer
137 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 ...
2
votes
0answers
23 views

Showing Linestring from SQL statement with CartoDB

I have cartodb sql statement to return what polygons are intersected by a linestring, but I'd like to have the linestring visualized over the polygons on the results. Also not add the linestring to ...
1
vote
0answers
24 views

Split a polygon based on density of points in ArcGIS 10.1

I have two layers: Polygon layer representing administrative boundaries Polygon layer representing topography (i.e. a map) In some of the administrative areas, the buildings (shown in the map) are ...
2
votes
2answers
65 views

Creating donut holes without losing existing polygons using ArcGIS for Desktop?

Using ArcGIS 10.1 for Desktop is there a way to do a similar operation to creating a donut hole or island in a polygon without losing the existing features? I have mapped small lakes as several ...
4
votes
1answer
343 views

Determining if Polygon Contains Negative Space using ArcGIS SOAP Web Service?

I am running queries against a polygon layer using the ArcGIS SOAP Web Service. A user selects a point within that layer and the resulting feature set contains PolygonN objects. Occasionally, the ...
4
votes
3answers
5k views

Filling in Donut Polygons using ArcGIS for Desktop?

I have a set of polygons that represent bodies of water. In the same feature are polygons that are the islands in the body of water. So for a given lake, there are smaller polygons within that ...
2
votes
1answer
128 views

Separate a polygon in different polygons depending of the distance to another polygon

I have a reference polygon "R", and others polygons (in grey). I want to separate each grey polygon in multiple polygons, depending on the distance to R with different Buffers : - The red line is R ...
5
votes
1answer
148 views

Select by location of doughnut hole polygon

I have vectorized the Corine Land class raster and want to select certain classes that are "inside" other classes. How can I select the polygons circled in blue? All the select by location options ...
0
votes
0answers
42 views

Intersecting Overlapping Polygons Individually in ArcGIS

Map Layers: -Census Tract Shape File w/Population Data -Set of Store Locations with 5 Mile Buffers (Significant Overlap Between Buffers) I have create feature layers for both and I am trying to ...
4
votes
2answers
592 views

Including polygons as part of network for ArcGIS Network Analyst?

I am creating a pedestrian walking network of a downtown area. I am digitizing line segments for paths and sidewalks, but I need to incorporate parking lots into my analysis. So far, I have been ...
3
votes
2answers
44 views

problem merging polygons based on a column value - using Spatialite

edit: as I am unfamiliar with any tools I decided to try my luck with PostGis. I imported my data. and executed the query : create merged as select delomrade_code, st_union(geometry) from grunnkrets ...
1
vote
0answers
29 views

Joining polygons with same boundaries

Sorry if my question feel stupid but I'm a new QGIS 2.4 user. My shape is composed of 7 polygons which are supposed to be adjacent (ie sharing sharing same nodes). Would like to join the polygons by ...
6
votes
2answers
4k views

How to smooth/generalize a polygon in qgis

Is it possible to smooth or generalize a polygon in qgis? Ìs there a plugin available like the generalizer-plugin for lines? I could convert my polygons to lines, smooth them and convert them back to ...
0
votes
1answer
212 views

CartoDB.js - Accessing table fields in hover function

I am new to CartoDB.js and javascript in general, and I am attempting to highlight polygons in response to a mouse hover. My plan of attack attempts to utilize one of the interesting templates ...
3
votes
1answer
57 views

Find small polygons inside big polygons

I'm trying without success to find a solution for problem in ArcGIS and this is the reason that I'm sending this message. I have one polygon shapefile with postal codes for South Africa (no Gap, no ...
2
votes
1answer
130 views

Highest DEM pixel in polygon

I'm working with QGIS and have a big DEM raster layer with height information and a vector layer with many polygons, representing 1 x 1 degree tiles. Now I want to find for every polygon the highest ...
2
votes
1answer
53 views

How to remove columns in a spatial polygon data frame in R?

My spatial polygon data frame (spdf) contains too many columns (variables) and I want to remove most of the columns entirely. I know how to do this with a regular data frame in R, but I am unsure how ...
3
votes
1answer
320 views

Why is ArcMap 10.0 editor deleting some added vertices and simplifying polygon?

I am using ArcMap 10.0. I am trying to edit (and add) vertices in a polygon. I start editing, (using "Edit Vertices" tool), and add many vertices in the polygon. Then when I am done, I save the ...
1
vote
2answers
34 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
1
vote
1answer
42 views

Dynamically drawing a polygon around another shapefile, ArcGIS 10.2

Let's say I have a vegetation raster that indicates the density of forest all over the world. I also have a shapefile that contains the admin boundaries of each country in the world. The easy part is ...
3
votes
3answers
194 views

How to export polygon coordinates to CSV (not WKT)?

I am new to QGIS, and I am now trying to export polygon coordinates from a shape file to a csv file, but so far all my attempts have failed. I have found numerous questions and answers about this, but ...
1
vote
0answers
25 views

spatialpolygons heatmap in R - NAs in grey?

I have a spatial polygon data-frame and I am trying to plot a heatmap via spplot. It's a map of Europe and the values for the heatmap are in a column of the data-frame. Plotting it works fine but I ...
3
votes
1answer
139 views

google map api v3 large/complex polygons

I have quite some large/complex polygons I'd like to overlay on a Google map. I can do this but wondered what the best/fastest way is to load them? I have tried using a KML but understand there are ...
1
vote
1answer
81 views

Automating Intersect between two polygon layers

I have a spreadsheet that has county-level occurrences of around 1000 species within the US in the column headings (Species State County). Thus, for some counties there may be multiple species. I ...
1
vote
0answers
29 views

Way to split and create buffer space between polygons in QGIS or ArcMap

After performing a feature extraction of rooftops, some of my buildings have been joined together as one polygon. I want to split these large polygons so that each new division is only covering one ...
2
votes
0answers
29 views

How can I merge adjacent polygons and return all (adjacent and not adjacent) as Multipolygon?

I have a postgres database with administrative boundaries and their geometry. Each of those boundaries have an ident number. What I want to achieve: First I want to select all rows which are ...
1
vote
1answer
155 views

How to construct a line from points in pyshp?

I am reading a shapefile for a pipeline and what I've noticed is that if I just draw a line from one point to the next (in the order I read them), there will be points where the line terminates, and ...
1
vote
1answer
24 views

Determine changes in land cover of isolated features over time?

I have a a study area of 2 Landsat scenes from 2013 which were classified for a specific natural community, and these areas have been isolated and extracted and digitized into vectors so that they can ...