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
191 views

Visualizing information when click in polygon‏ - Spatial join

I am new to cartodb, right now I am trying to do something similar to the cartodb tutorial: Create your first map with CartoDB.js, but with polygons using my own map. For example: I did a spatial ...
2
votes
1answer
210 views

How to check how much of a line (percentage-wise) is covered by a polygon in arcpy?

I'm searching for an efficient way to check if a line is covered by a polygon (see image, this case should return 2x "true"). Right now I only check wether a line is within a buffer with line....
1
vote
2answers
133 views

Distance from one point to many polygons

I'm using ArcMap 10.1 and have a shape file of polygons of municipalities. I also have the coordinates of the centroids of the polygons (if I need to use them). I want a column in my attributes table ...
1
vote
1answer
64 views

How to automatically add identical new polygons to a layer?

I am seeking a way, using QGIS, to automatically add polygon features identical to others on the layer. In this case, they are water valves on a water network. Anyone know of a user-friendly way to ...
1
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1answer
431 views

Algorithm to move polygon nodes when simplifying

I want to simplify polygons that come from a raster analysis. In order to avoid overlap and gaps, I first convert my polygons to lines. The problem is that all algorithm are then keeping the two end ...
3
votes
1answer
341 views

QGIS - How can I convert a raster file to a vector file without making same value cells into one polygon?

How can I convert a raster file to a vector file without making same value cells into one polygon? In the attached image, the values "2124", "2269", "2321", "2634", and "2920" are the polygons ...
0
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1answer
530 views

Smooth polygon boundaries

I have a kml file with boundary polygon. It has a lot of gaps and overlaps in them. I converted them into shapefile and tried to use smooth and generalization feature tool in a couple of GIS software'...
2
votes
3answers
720 views

Shapefile with overlapping polygons: calculate average values

I have a very big polygon shapefile with hundreds of features, often overlapping each other. Each of these features has a value stored in the attribute table. I simply need to calculate the average ...
2
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0answers
137 views

Simplify by number of points in QGIS

I have a fairly simply question about something I just don't know how to do. I am aware you are able to simplify polygons in QGIS based on distance tolerance but my questions is, is there a way to ...
1
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0answers
43 views

How to enforce labels for all polygons?

I am trying to label polygons but it does not always work. Either the polygon is quite large, then the label appears, or the polygon is small, then the label is not displayed. I've already tried to ...
2
votes
3answers
460 views

How to generate dartboard shapefiles using ArcGIS for Desktop?

I am rather new to ArcGIS and I have a simple question regarding a problem I cannot fathom. I am attempting to generate a polygon 'dartboard' shapefile. Radially, there should be a circle from 0 to ...
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2answers
303 views

CartoDB Vis - Multiple layers mouse interaction?

My map visualization has two layers: 1) A city layer where the cities are represented as standard markers. 2) A county layer underlying the cities which has county level aggregate data. The layer ...
0
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1answer
34 views

cut off part of catchment

I want to edit a polygon as that I cut off a part of it. I want to freely make a line that define where the polygon should be seperated. I have tried to useedit vertices but it does not seem to be a ...
0
votes
1answer
81 views

How to generate evenly sized polygons within a boundary

I have an area and need to create evenly sized polygons within the area. It doesn't matter where the polygons fall, only that they don't overlap and each area is the same. They needn't be squares/...
3
votes
2answers
441 views

Postgis 2.0 simplifying multipolygon

I have a data set of national boundaries for the African continent. These are in a multipolygon table in postgis. Each country has multiple entries (rows) such that some of the countries in my table ...
1
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1answer
1k views

Converting a raster to a polygon

I need to convert a raster into a polygon, and I ran into "Error 000863: Invalid GP Data Type" After searching, I saw this solution online. Basically I needed to convert the float raster to an ...
8
votes
2answers
1k views

Simple way to detect/select border polygons of a shapefile

I am looking for a simple way to detect/select border polygons of a shapefile. Border polygons are here polygons that are not completely surrounded by other polygons i.e. polygons located at the ...
2
votes
1answer
63 views

Is there a way to use some sort of “instancing” when storing polygons in a spatial database?

I am quite new to GIS database addons, and I am still exploring the possible uses for them. In general the idea of storing objects indexed by their position which enables additional operations is ...
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0answers
95 views

OpenLayers: How to move smaller vectors to front?

I've got a problem that's been bugging me for quite some time now. As you can see in the image below I've got som vectors that ends up beneath bigger ones, and despite all my efforts of trying to ...
3
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3answers
2k views

How to get count of non-NA raster cells within polygon using R

I've been running into all sorts of issues using ArcGIS ZonalStats and thought R could be a great way. Saying that I'm fairly new to R, but got a coding background. The situation is that I have ...
1
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2answers
301 views

Conversion of diagonally adjacent pixels into one polygon?

I am trying to vectorize a raster whose digital numbers indicate different classes they belong to. ArcGIS and QGIS yield similar results: separate shapes out of pixels sharing the class that are ...
1
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2answers
360 views

Polygon inside polygon invalid in QGIS

Looking at this map data from naturalearth (part of Oman & UAE to be specific), each country is defined as a multipolygon. In this case UAE (in red) contains two polygons and Oman (beige) three. ...
2
votes
2answers
160 views

How to select part of the polygon

I have a shapefile of the country. I need to select only percentage of that polygon for demonstration purposes. As an example, how to select 60% of polygon? I am using ArcGIS 9.3.
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1answer
153 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 ...
1
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2answers
133 views

Joining data points to matching polygons

I have polygon data on coral reefs at great barrier reef and separate point data for areas of coral bleaching. I have created a clip that only includes points that exist with in the reef polygons. ...
6
votes
1answer
2k views

calculate {minimal} distance between polygons in R

I have calculated the surface area of species distributions (merging polygons from shapefiles), but since this area can be comprised of quite distanced polygons, I would like to calculate some measure ...
5
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3answers
756 views

Polygonize vegetation area from Landsat7 RGB using QGis / Bilko?

I'm trying to extract the areas with vegetation as a polygon-shape from a landsat7-image, 30m resolution, RGB, using QGis 1.8 or Bilko or (hopefully in the near future) ArcGIS. The area is in Northern ...
5
votes
3answers
492 views

How to combine stacked polygons within a shapefile?

The image below shows my shp-file. Every polygon has the same transparent color. So a darker blue means, that several polygons are stacked! How do I cut every polygon with each other so no polygons ...
0
votes
1answer
254 views

How can we split a polygon within another polygon in Qgis? [duplicate]

How can I split the green area as a separate polygon fro the grey one in QGIS?
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0answers
355 views

Why might ArcGIS Export to PDF lose polygon?

How can I solve this problem? After exporting my map to pdf (or any other format), the exported map does not show the basic-polygon-layer, but only a blue/turquoise background with line and point ...
0
votes
1answer
95 views

Using attributes of a polygon in one layer to identify polygons in another

So I'm in the process of developing a web application, I am using open source tools so qgis, postgis, play framework for the web app. And I have come across an interesting problem that I'm trying to ...
0
votes
1answer
87 views

problems using the Split Features tool [closed]

i'm using the split features tool to create two polygons from a bigger one. The problem is, when i save the split i have done, half of the polygon disappears. But sometimes, after doing some more ...
3
votes
1answer
572 views

remove land area from marine region polygons

In my pursuit to merge multiple polygons for the purpose of calculating the surface area of marine species distributions, using shapefiles from Marineregions, I am now trying to remove potential land ...
2
votes
1answer
826 views

How to define polygons overlapping each other?

I have a shapefile of landuse in different catchments. I want to calculate the percentage of each landuse category in each catchment using Tabulate Intersection. Before using this tool, I had ...
0
votes
1answer
2k views

How to extract geo data out of a polygon shape file into csv kwt [duplicate]

I have a polygon shape file that contains all the neighborhoods in the Netherlands. My aim is to export the neighborhoods and coordinates to csv file (KWT). Without success I tried (with QGIS) these ...
1
vote
2answers
465 views

unionize intersections of merged polygons

[Updated quesion] I am using the following code to merged polygons from shapefiles for the purpose of calculating the surface area; library(maptools) library(rgdal) library(rgeos) #enter slots, e.g....
7
votes
1answer
984 views

How to determine the longest line segment within a polygon that passes through its centroid?

A PhD student approached me recently asking how one would determine the longest straight line that passes through the centroid of a polygon, the output being a polyline rather than just a table of ...
1
vote
2answers
115 views

qgis polygon to coordinates

I have the ordnance survey postcode polygons, i can get the centre point on the postcode (Using polygon centroids) and all the corner coordinates (using extract nodes) Does anyone know how to export ...
3
votes
2answers
477 views

UK area boundaries

I'm working on a web project that requires polygons and lat long coordinates for the boundares of towns, citys, countys and postcodes. Does anyone know where i can obtain this data? i know rightmove ...
2
votes
0answers
51 views

how to assign unique attribute value per neighborhood? [duplicate]

I have a feature class of adjacent polygons and I want to assign an integer attribute value to my polygons based on the following rules : a polygon must not have the same attribute value than any of ...
3
votes
1answer
188 views

Is it possible to split a polygon inside another one in QGIS simply?

I can split polygon if I put the points of start and end outside the boundaries. How can I do the same if I have a part that I want to split completely inside a polygon. In Arcgis I can do it if the ...
2
votes
4answers
2k views

Merge large number of polygons using QGIS

I have a series of polygons that are the output of another GIS program - I need to merge the polygons into a single polygon. I have tried a couple of different methods with no luck. I have tried to ...
0
votes
2answers
77 views

Select area which is at least x meters away from other geometries

In my table I have the build-up area from a region as a big number of polygons. urban_area: id | name | geometry(polygon) I was wondering if and how I would be able to find the area within a ...
4
votes
1answer
2k views

ArcMap 10.1 SP Spatial Join Problem (lines within polygon)

I have a line layer (faults) and a polygon layer (fishnet grid). The fishnet has a risk of earthquake attributed to each polygon. I want to take that risk value and give it to the fault lines which ...
3
votes
1answer
418 views

Postgis identify points on the polygon border

I have points geom in gid,pt_geom and polygon geom in gid,pl_geom. Some of the points are inside polygon and some are outside polygon, others are on the polygon boundary. Is there any way to ...
2
votes
1answer
1k views

Creating polygons using offsets from other polygons

Wondering if you I might get some advice on how to best create a polygon within a polygon based on an offset in ArcGIS. I have one layer that is a cadastral layer and another that is a building ...
2
votes
3answers
815 views

How can I change map scale in ArcMap, after I'm almost finished digitizing? [closed]

I'm just about to design a map that represents different areas in my immediate living environment. I Unfortunately made a big mistake at the beginning of my project. The current scale is given by ...
3
votes
1answer
7k views

How to combine (join?) two overlapping polygons to determine combined area they cover?

How do I combine (join?) two overlapping polygons to determine the combined area they cover in ArcGIS 10? I am sure the Geoprocessing tools can do it, but just how eludes me.
2
votes
2answers
3k views

Polygon country boundaries in decimal degrees

Using Google Maps, I'd like to create draggable polygons (on the fly) of country boundaries (they don't need to be particularly precise). Something similar to this, but for countries. So I want the ...
1
vote
0answers
125 views

Need to enhance a function for creating quadrants within polygons

I wrote a function that creates arbitrary quadrants within a polygon SELECT (quadrant(20,0.0,90)).* The first parameter is the polygon ID, the second one is the start angle and with the third one ...