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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8
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1answer
154 views

Cutting out the world into polygons of equal population size

I would like to cut out the world into polygons of equal population size, say 100 million persons (starting for example with raster data of population density as provided by the NASA). I know that ...
6
votes
1answer
120 views

Suitable algorithms for simplifying isochrone polygons

I'm looking for an algorithm for simplifying isochrones which were generated using OSM data. These are generally characterised as having lots of small "holes" mostly due to missing OSM data but also ...
5
votes
1answer
393 views

Rgeos drops associated values when intersecting polygons

I am trying to intersect two SpatialPolygonsDataFrames and get a SpatialPolygonsDataFrame as the result. Unfortunately, using the gIntersection function from rgeos (which works impressively quickly ...
3
votes
1answer
99 views

How to map flood areas from a set of points containing surface and height of water?

I am working on the damages made by the typhoon Haiyan. I use QGIS 2.0 with extensions and toolbox, and MapInfo. I have vectors, rasters of the place. I want to map the flood area along the ...
3
votes
1answer
104 views

Postgis 2.0 geographic polygon has max longitudinal range

My problem is that I have a load of geographic point data (srid 4326) in a table. A user may do a bounding box search - essentially create a polygon as follows: l_poly geography(Polygon,4326):= ...
2
votes
1answer
14 views

Intersection between polylines feature to polygon in QGIS

I would like to transform a line shapefile into polygons. However, the tool Vector>Geometry>Line to Polygon doesn'to work to me. What I would like to do is using the intersection between lines and ...
2
votes
1answer
21 views

Percentage of a polygon at, or less than, a specific height (supplied by a raster)

I am using QGIS to process some LIDAR data. I need to be able to define the area of a pond with respect to its depth (i.e it is 100m^2 at 32mAOD and 500m^2 at 33mAOD). Is there a way of finding the ...
2
votes
1answer
30 views

SQL Server equivelent to Arcmap Intersect for polygons?

I have three different sets of GEOMETRY Polygon datasets in SQL Server that completely overlap. I need to create a new dataset that has a polygon for each unique area of the three layers. So ...
2
votes
1answer
168 views

What methods exist for geohash of polygon?

GeoHash is an excellent method to code the latitude and longitude of a point into a string. It's concise, due to the use of numbers + letters, and the precision can be tuned adding characters at the ...
2
votes
1answer
42 views

Is there a way to clip a polygon layer according to DEM elevation?

I have a polygon layer on top of a DEM. Is there a way to clip the polygon layer according to elevation, ie the clipped result being only those areas of the polygon layer between x and y altitude? ...
2
votes
1answer
167 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 ...
2
votes
1answer
25 views

Selecting Polygon Features in QGIS Lisboa

I want to select and save as a separate shape file, a smaller section (polygon) from a whole island country which includes both land and shallow habitat coastal features (like coral reefs) and when I ...
1
vote
1answer
16 views

Point in zone problem in calculation

I have a strange problem that i believe its because the zone pass through international date line. My goal is to find if a point is within a zone and I use the geoPHP library, everything seems to be ...
1
vote
1answer
35 views

Cutting polygons into smaller (more regular shape) chunks

I came up with a polygon shapefile like what you see here. There are some small polygons which exactly match what I want, though I want to cut(split) those bigger ones into smaller pieces. So far I ...
1
vote
1answer
50 views

How to add IDs of the links composing a polygon?

I built up a polygon layer from a road network for finding roundabouts using the compactness factor of a polygon. Then I have to intersect the extracted roundabout polygons with the road network so ...
1
vote
1answer
102 views

Is it possible to draw polygons along Google Maps Polyline?

Web application has option that user draws polyline on Google Map. After he draws it, there is a button 'Add polygons', which should draw polygons along that line, based on some width and height in ...
1
vote
1answer
53 views

QGIS 2.4 How to label a polygon

I have tried labeling a polygon using the layer properties>label function but it doesn't show my label. How and where do I type the text I want and get it to show?
0
votes
0answers
57 views

Determine the list of circles (from 100K circles), that overlap with a given polygon

This question was asked on StackOverflow, came here because no response has been posted so far. Existing data structure we have polygons represented as an ordered list of lat/long coordinates and ...
0
votes
0answers
83 views

How to split an oblong, irregular polygon layer into even pieces?

I have a polygon layer (landuse) that I want to split into 100 meter pieces. The polygons show landuse along a road. I want to split the polygons layer so that I can then calculate the percentage of ...
0
votes
0answers
45 views

Split polygon into four with respect to single point

Some days ago one of my colleague came to ask me a query related to Geometries. The situation is as....There is one Polygon(suppose a city polygon) and there is one point(suppose user's current ...
0
votes
0answers
45 views

Split/Erase/Differentiate polygon by polygon within a same layer

Is it possible to split a polygon with a polygon within the same layer in QGIS ? As in the image, i want the Polygon 2 to be split & the pointed area has to be retained as a separate polygon. ...
0
votes
0answers
48 views

save polygon from image to PostGIS database

I'm working on a software to detect buildings from satellite imagery. so far I have managed to separate the building with other objects of the image. My problem now is how to save every building in ...
0
votes
0answers
36 views

QGis Filtering postgis layer with boundbox

I know It is possible to split a polygon feature by interactively drawing a line over it in QGIS 2.0 with the Split Feature command.The issue i have is that postgis layer i am trying to work on is ...
0
votes
0answers
49 views

Why does it take so long to run zonal statistics?

QGIS 2.0 Windows 7 I have pulled agricultural data from NASS CDL in tiff format. I want to track where a certain crop has grown over the years. My intention was to use a county shapefile overlaid ...
0
votes
0answers
42 views

Splitting polygon layer and joining attributes

I have two shape layers -- one a layer of counties in Florida and another a layer of MSAs in Florida. I would like to generate a new layer that has the following properties: MSAs that overlap more ...
0
votes
0answers
46 views

GRASS GIS - v.select- ERROR: bad allocation -

I'm quite new to Grass GIS. I have two vector maps, one of a grid (each grid cell is a polygon) and one of a much larger polygon. I've been trying to select the grid cells that lie completely within ...
0
votes
0answers
35 views

QGis 2.0.1 (german version): Transect with square polygons

I would like to create with QGis 2.0.1 ( Dufour , german version) several square polygons (1km ²) that seamlessly connect to each other, so that a strip ( transect ) of 9km times 1km length results . ...
0
votes
0answers
90 views

How to get polygon points for all regions inside a city polygon?

Is it possible for me to get all polygon points for all regions inside a city polygon? I am building a website where i need city level polygons as well as polygons for all sectors and estate areas in ...
0
votes
0answers
47 views

Is there a way to set different levels of transparency (opacity) for a polygon's border and its interior?

I have some polygons which I'd like to display with their interior displayed at a higher transparency than their borders. Right now, I am doing it by creating two separate layers with the same data ...
0
votes
0answers
226 views

Add labels for printed map (GeoTools)

I have some problems with labels for printing map with GeoTools. Next code (with some cuts, code on Scala language) can help me for printing map: val map = new MapContent() val parser = new ...
0
votes
0answers
20 views

Is it possible to create new polygon with the streaming mode on QGIS1.8?

I would like to create a new polygon with the mode of stream. In Arc GIS, it is possible to change the mode from stream to normal that vertec is placed based on click. Strem mode means vertex is ...
0
votes
0answers
42 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 ...
0
votes
0answers
98 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 ...
0
votes
0answers
112 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 ...
0
votes
0answers
37 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 ...
0
votes
0answers
129 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 ...
0
votes
0answers
29 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
0answers
46 views

Polygon shading is darker in certain areas

When drawing in qgis i am encountering an error when drawing large polygons snapped to multiple points. Polygons that have this shading in certain areas are not displaying correctly in other ...
0
votes
0answers
94 views

Polygon dynamic grid creation for a shape file

I have used QGIS Vector->ResearchTools-> Vector Grid to create a 1lat x 1 long grid for the landpolygon shape file (from osm). Now, I am interested in creating dynamic grid for the original ...
0
votes
0answers
99 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
votes
0answers
823 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 ...
0
votes
0answers
60 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
0answers
60 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
votes
0answers
111 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 ...
0
votes
0answers
1k views

How to write a point-in-polygon query for Postgis?

I'm trying to write a query in Postgis which will return all rows where a dynamically changing longitude/latitude point resides within the geometric polygon of that row (in the geom column). This is ...
0
votes
0answers
156 views

Offset a Polygon defined in Lat Lng points by a given distance of miles or km

I am trying apply a positive offset/buffer (enlarge a shape equally from the borders) to a polygon that is made up of a series of latitude/longitude coordinates by a distance that is defined in either ...
0
votes
0answers
115 views

Where can I get polygons for the Municipalities of Puerto Rico?

I'd like to find GeoJSON files to draw the polygons of municipalities of Puerto Rico. It might be nice get the Nokia Map (or any reasonable publicly available map) of the same regions and overlay ...
0
votes
0answers
450 views

How to do a spatial join if QGIS 1.8 keeps crashing?

I am trying to perform a simple spatial join (adding polygon data to points) in QGIS 1.8: target vector: points join vector: polygons take attributes of first located feature keep all records ...
0
votes
0answers
684 views

How to remove small polygons in ArcGIS 10 using extension by Gonza2?

Does anybody have experience and success working with the Remove small polygons from a feature class script tool by Gonza2 in ArcGIS 10? The extension works perfectly in previous version of ArcGIS ...
-2
votes
0answers
38 views

Totaling Population within A Polygon

I am trying to count total populations within several arbitrary polygons using census block data. How can I get a total number per polygon?