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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2
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1answer
96 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
123 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 ...
7
votes
4answers
542 views

Performing a reverse clip in ArcMap?

Is there a way to perform a 'reverse' of the clip function in ArcMap, I'm not exactly sure how to explain this so here's a diagram:
1
vote
2answers
47 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
1answer
169 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 ...
3
votes
2answers
57 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 ...
3
votes
1answer
43 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 ...
4
votes
1answer
110 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 ...
0
votes
2answers
46 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 ...
16
votes
4answers
710 views

What are the benefits of hexagonal sampling polygons?

I am always on the lookout for useful methods to sample or partition study areas (usually in the form of raster datasets) into smaller units. Recently, I read an ESRI blog post about a new tool for ...
2
votes
0answers
43 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 ...
0
votes
0answers
35 views

Fixing “Assigning the return value of new by reference is deprecated” error

I just downloaded the vertex.php, polygon.php, and polyExample.php files from this site: http://www.phpclasses.org/package/2544-PHP-Perform-geometric-operations-on-polygons.html only to find dozens of ...
2
votes
3answers
75 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
votes
3answers
112 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 ...
2
votes
1answer
72 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 ...
1
vote
0answers
85 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 ...
2
votes
2answers
166 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
1answer
128 views

How to improve speed of rendering polygons from Postgis in Leaflet?

I want to improve speed of rendering polygons in my Leaflet map. Polygons are stored in Postgis, and are rendered with select query with bbox. I wonder can I cache somehow those polygons? I read ...
1
vote
2answers
208 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, ...
1
vote
1answer
91 views

How to extracting raster data to multiple polygons?

I have a reclassified raster dataset (10 classes) and I want to find out the area of each class contained within multiple (hundreds-to-thousands) polygons. I have all the polygons in the same ...
1
vote
1answer
56 views

Polygons not appearing when creating shapefile based on criteria using GDAL and Python (area calculated properly)

I am looping over the features of a shapefile containing multiple polygons. If certain criteria are met, I want to save the current feature in a new shapefile. I am doing this using GDAL 1.10.0 with ...
2
votes
1answer
78 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 ...
0
votes
0answers
77 views

Can I simplify polygons in QGIS by Size?

Just wondering if it's possible in QGIS to simplify polygons based on size? I've done it many times using the tolerance level to reduce the overall size however in this case each polygon cannot be ...
3
votes
2answers
147 views

How to Select “Inverse” of intersection of two polygon layers?

I'm wondering if there's a way to intersect two polygon layers, take the intersection, and remove that from one of the polygon layers, making a new layer out of whatever is left over? Basically, the ...
1
vote
2answers
54 views

How to convert small overlaping polygon features to inner ring in QGIS

I have a polygon vector layer with overlapping features (like below) and I would like to convert the features that are fully contained inside the bigger polygons (ie feature 2 and 4 below) into inner ...
0
votes
1answer
45 views

Problems with Polygon Reshape Feature

I'm new in this forum, and i need some help with my project. I've created a polygon and closed my project, after opening the project again, i can't use the Reshape Feature tool in that specific ...
2
votes
3answers
122 views

How to remove vertices or lines within a polygon?

I have transformed a *.dxf-file into a polygon shape-file. In many of the polygons i have lines whicht do not belong there but i can not delete them as i normally delete vertices on polygons by ...
0
votes
0answers
65 views

Calculating distances between boundaries of polygons with Python

I have two sets of shape-files which have to be worked on within a Python Script. Those two Shape Files might differ from each other (same thematic content, but 2 different epochs). If there occurred ...
3
votes
1answer
111 views

Tornado Data Points: Linking 2 Points in QGIS on the Same Row

So I've got these tornado .csv files that have two latitude & longitude entries with the left-most in the table being the beginning point and the right-most being the ending point of the tornado, ...
0
votes
0answers
29 views

Ignore Transparent Pixels for Bounds Determination

I am displaying an Image using GWT OpenLayers on a map. My Image has transparent pixels and the system which returns my Image returns a footprint that is equal to the image plus the transparent ...
3
votes
2answers
118 views

Comparing 2 polygon shapefiles for differences [duplicate]

I have 7 shapefiles, each representing a year, all containing lots of polygons (c. 500,000). My aim is to take any 2 of them and compare how they have changed in terms of size and shape of polygon. (i ...
2
votes
4answers
110 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 ...
1
vote
0answers
67 views

DotSpatial: Convert a Polygon Feature to System.Drwing.Region

I want to paint a Polygon region with a color. I know I can use Symbolizer to do this but I want that region to blink (change it's color in a timer) and using symbolizer seems to be slow for this ...
1
vote
2answers
503 views

Determine if point is within an irregular polygon using Python

I would like to create a mask of a grid where points are evaluated as either 1's or 0's depending on if they lay outside of an irregular (i.e. not rectangular) polygon. I have a set of high-latitude ...
2
votes
1answer
36 views

Automatically chopping lumps off polygons

I have a load of polygons that were originally digitised from CAD. These unfortunately include traingles that were used to sybolise the direction the polygon is facing. As can be seen here: The ...
2
votes
0answers
92 views

Joining nearest neighbor small polygons using R

The figure shows a plot of numerous polygons (zoom in) made from a raster file by require(sp) require(raster) pol100 <- rasterToPolygons(r, fun=function(x){x==1}, dissolve=FALSE) There polygon ...
0
votes
1answer
91 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
2answers
99 views

Convert surveyor's calls in excel table to polygon shapefile

Do you know of a way to take surveyor's calls from an excel file (for example: N35-45-15W 60.0 ft, etc) and have them generate polygon shapefiles point by point in GIS? I know you can easily do this ...
3
votes
1answer
52 views

How to re-ID polygons with sapply instead of for loop

I have a line of code that renames the id's of polygons in a SpatialPolygonsDataFrame by directly manipulating the ID slot of the polygon. I'm a bit slow when it comes to sapply, having used for loops ...
1
vote
2answers
110 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 ...
0
votes
0answers
18 views

calculate proportion of polygon greater then 40 degrees in grid cell QGIS

I would like to calculate the proportion of greater then 40 degree slope within my polygon grid cells. I have a Slope Raster layer for my given area and have a polygon that overlays this raster ...
0
votes
1answer
144 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 ...
0
votes
0answers
29 views

Reshape tool stops working in QGIS 2

I am using QGIS 2 on Windows 7. I am reshaping some polygons which I am supposed to correct with the reshape tool in the "advancing digitization" bar (). Somehow, after some changes are made ...
2
votes
0answers
44 views

Using ST_Affine() and trans_param() functions on vector layer

After reading this post How to georeference a vector layer with control points? I decided to give it a try to move/rotation/scale a polygon using Postgis. I have two polygons, polygon_from and ...
2
votes
1answer
92 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 ...
2
votes
0answers
194 views

How do I set the fillcolor of polygons in Leaflet.js dynamically?

I'm using the interactive chloropath example for leaflet.js I figured out how to make each of my polygons add a running tally of values to the bottom of the page after each polygon is clicked. Upon ...
2
votes
1answer
153 views

PostGIS: Calculate the length of just the portion of linestring that intersect with a polygon

I want to calculate the portion of the linestring that lies within the limits of a polygon. Better with an image What is the length of the portion of linestring within Province A? and within ...
0
votes
0answers
24 views

Using a grid of points to generate polygons [duplicate]

I have a csv that has lat/long points for all corners of a perfect grid over an area I am working with. I need to take these corners and generate a shape file with individual polygons for each grid ...
0
votes
0answers
34 views

ArcGIS10 Highest point via polygon features

I am using ArcGIS 10.0 with 3D Analyst, Spatial Analyst and Military Analyst. I feel like I am halfway to solving a problem but do not seem able to completely solve it. I have a polygon shapefile ...
4
votes
1answer
88 views

Merge polygon without attribute (in field) with nearest polygon with attribute

In the image you can see districts in BLUE with attributes (name of district) and small pieces in RED. The red polygons belong to the blue and I want to merge them. The RED are only towards the ...