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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0
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1answer
731 views

OpenLayers polygon fill not working with GeoJSON file as source

I'm trying to visualise some data in a custom shape on a map, and I'm stuck with styling it. I'm currently using the openlayers framework in combination with a geoJSON file that I generate in code. ...
3
votes
1answer
407 views

Qgis analysis on polygon

I have a data table mapped and the table also contains further information of interest, beyond the lat/long of the specific data points. I want to be able to draw a polygon and then simply have a ...
11
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4answers
2k views

How to colour polygons with a completely transparent fill using MapServer?

Is it possible to fill polygons so that they are completely transparent in MapServer? I want to have a black background that is slightly opaque, and wherever there is a polygon I want that to be ...
1
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0answers
37 views

area weighted average for overlapping polygons [duplicate]

Possible Duplicate: How to use NASS county level crop data to estimate crop acreage in hydrologic regions? It seems like an easy problem but I don't know how to go about it. I have two ...
3
votes
2answers
796 views

How to filter out multipart polygons and then buffer?

I've written a small script trying to accomplish the task described in the question title. It basically looks like: in_fc = '...' # Some shapefile goes here # Get the fields (column names) of the ...
3
votes
1answer
2k views

Merging multipolygon data into a polygon

I have a MultiPolygon representation of some shapes in POSTGIS, I am trying to convert them to Polygon data. I tried, st_geometryn(r.geom, 1) but that didnt work because the way polygons are ...
1
vote
0answers
853 views

How to handle postgresql/postgis geometry type errors in a function?

I have created the following function in PL/SQL to make a polygon from a set of linestrings: CREATE OR REPLACE FUNCTION _myfunction( _fid integer, _rid integer ) RETURNS VOID AS $$ ...
4
votes
1answer
782 views

Extracting donut holes as separate layer in QGIS

Does anyone know how I can extract the holes in a polygon layer as a separate layer in Quantum GIS? An example could be a country with a number of lakes cut out of the polygon - I need the lakes. I ...
5
votes
1answer
2k views

Dissolving specific polygons inside SearchCursor with Python in Arcmap

I have a layer with catchment polygons. For those that are smaller than a certain size, I want to merge with an adjoining polygon (namely the one downstream). In the attribute table I have a GridID, ...
5
votes
2answers
884 views

How to combine data from overlapping polygons?

Here's what I'm working with: Shapefile of the current 32 Congressional districts for all states Shapefile of the tract boundaries for Texas A DBF format table of Hispanic counts and proportions for ...
3
votes
0answers
126 views

Why doesn't Polygonizer copy the line ids to my polygonized shapefile?

I am trying to convert a line shapefile into a polygon shapefile using Polygonizer plugin, and when my new polygons are created all the cells in my id field are "Null", although I have clicked "copy ...
3
votes
2answers
402 views

Determine density or cover from a raster layer that has been clipped by a polygon

I am a very new GIS user using ArcMap 10. I have a raster layer of tree canopy that I have clipped so that the layer is in a polygon that is a circle with a 2km radius. I have done this for four ...
3
votes
1answer
487 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 ...
7
votes
2answers
2k views

How to sum pixel values within a polygon zone in QGIS?

I have two layers: a raster layer and a vector layer (polygon). I can see the values of the raster pixels but I don't know how to combine them with information from the polygon layer. More ...
2
votes
0answers
170 views

How to dissolve polygons that have been split back into their original polygons?

I had a feature class containging about a thousand polygons.After some processing such as intersecting, dissolving, merging, more intersecting, I ended up with a feature class of about 6000 polys. ...
2
votes
2answers
2k views

Problem creating polygon features using ArcObjects / ArcGIS 10

I need to create a grid of polygons. Each polygon is rectangle, thus has 4 corners (vertices). When I create polygon features using ArcObjects they seem to have wrong geometry, which results in wrong ...
2
votes
1answer
253 views

Obtain normalized raster average per polygon?

I have a raster that contains percentages of total forest killed plus a polygon layer that defines different zones. My goal is to find a good statistical representative that describes the forest ...
1
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0answers
152 views

Creating responsive interaction with tiled maps

I think I may have two conflicting aims but... I need to create responsive Choropleth map very similar to http://leafletjs.com/examples/choropleth.html or ...
1
vote
2answers
171 views

information from a shapefile to another shapefile

I am very new to GIS and learning by myself so what I'm about to ask is possibly quite basic. I am using QGIS. I have a shapefile, which categorizes areas (land cover) by numbers (corresponding to ...
7
votes
2answers
411 views

How do different GIS systems determine a Polygon's interior?

I'm interested in understanding how real-world GIS systems and their data encode Polygons. Specifically, how do they resolve the ambiguity of a Polygon's interior on a sphere? Background: in 2D, ...
6
votes
1answer
533 views

Generalize large polygon-file

I have a large polygone file with landuse information (6 classes). Its vectorised from a raster classification so the polygons are all angular. Any of my tries to generalize with v.generalize (sneaks, ...
0
votes
0answers
57 views

Point to Polygon [duplicate]

Possible Duplicate: Create new polygon layers from postcodes latitude & longitude I'm running QGIS 1.8.0 I have a list of points that I need to convert to one polygon. So far I have ...
5
votes
1answer
76 views

Geographic locators within Polygons

I have a list of geographic locators and a boundary file. In QGIS, is there any way merging them together to create a lookup saying this boundary contains these locators? Not the number the actual ...
1
vote
1answer
2k views

QGIS, how do you break segments of a polygon, ie break 1 polygon into 2 or more?

I have a polygon but would like it to be in broken up to put into different layers. I can't work out how to do this.
4
votes
5answers
1k views

Python loop Polygon to raster not working

I want to convert a large number of different shp polygons to raster in ArcGIS 10.1, using an existing field column "class" for the new raster classes. I am not very fluent in python but I thought ...
6
votes
3answers
303 views

Filtering features using geometric attributes of polygons in ArcGIS Desktop?

Given a polygon featureclass containing many polygons of different sizes and shapes, which geometric attributes (area, perimeter, etc) could be used to filter the polygons? It's probably best to ask ...
4
votes
1answer
322 views

Splitting polygons leaves null values

I'm trying to split polygons with overlaping line features, using Split Polygons tool from Topology toolbar. The problem I encounter is that only one from new polygons have old attributes and others ...
11
votes
6answers
2k views

How do I make a heat or Choropleth map that uses polygons in QGis?

I've been playing around with the heatmap plugin for QGIS and I am wondering if it is possible to make heatmap with using a similar plugin/tool that uses polygons as well as points? I would like to ...
4
votes
4answers
3k views

Remove Polygon Islands

I'm really stumped with the problem. I have a polygon layer with no intersects or holes and I need to remove some 'islands', as defined by attributes of a certain size within the layer. It's a hard ...
2
votes
1answer
376 views

joining a table from zonal statistics as table with a layer, problem with reserved names

I have a raster file (percentage of total forest killed) and a shapefile with polygons (municipalities). I thought as a first step I would like to find out which municipality shows the greatest ...
2
votes
2answers
991 views

Converting polygon layer to *.txt files using ArcGIS Desktop?

Is there any way to convert polygons that do not have coordinates in the attribute table to a txt file with coordinates. I will be using the txt file in a different software (not ArcGIS), so I need ...
2
votes
2answers
240 views

How can a style be set on a specific polygon using OpenLayers?

Using a polygon id, I want to highlight a polygon, while the mouse is outside of the map area. I can identify the polygon using the following approach: x = 53; for(i=0; ...
3
votes
1answer
3k views

How can GeoJson polygons be colored programmatically using OpenLayers?

I'm experimenting with dynamically setting the color values of a geojson polygon. In my geojson file, there is an attribute for each polygon called pop_den. I am trying to update the fillcolor of the ...
8
votes
3answers
3k views

Using polygons to apply unique value to all raster cells within those polygons?

In ArcGIS 9.3, I have a raster file that I would like to "mask" with polygons, giving a single value to all the raster cells that overlap the polygons. How can I do this? Here's a screen shot, ...
2
votes
2answers
1k views

Zonal Statistics as table creates output but some are Null

I have temperature as a raster file and different ecoregions of a province as polygons. What I want to do is calculate the mean temperature per ecoregion. I succeeded in doing this by Zonal ...
3
votes
3answers
4k views

Polygon to Raster Tool Problem

I am trying to create a raster data set from county level polygon data for the US. I have successfully created one raster from a dataset, but when attempting another, it does not work. I am ...
9
votes
2answers
6k views

Converting point sets to polygon boundaries

I'm trying to convert sets of points to their respective polygon boundaries. I think this is something like a Voronoi diagram or Convex Hull, but not quite. I'm sure there's a technical term for it, ...
2
votes
1answer
264 views

how to create an outline polygon (footprint) from raster data with postgis?

how can I create a polygon, containing the actual outlines (aka footprint) of a raster file with postgis? I just need the outlines of the data containing parts of the raster. ST_PixelAsPolygon ...
2
votes
1answer
179 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
2answers
1k 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 ...
5
votes
1answer
103 views

How do you edit a stack of polygons simultaneously?

Using ArcMap 10.1. Lets say you have 100 polygons that all are in the exact same shape and in the exact same place. They appear to be one polygon. How would you edit the shape of all 100 at the same ...
6
votes
1answer
436 views

How to draw shapes with highest possible decimal accuracy

I am trying to read input of lat and long to draw the shape based on condition.The input is standard array of lat and long with 15 decimal accuracy. I am realizing - I am loosing some decimal accuracy ...
12
votes
3answers
3k views

Self intersections for polygons, how to solve?

I have a question about repairing a self intersecting polygon shapefile. I have a shapefile containing Polygons (ZM) which have self intersecting features. If I use the "repair geometry" tool, it ...
2
votes
1answer
500 views

Is it possible to have self intersecting polygons in shapefile?

GIS vector data for example shapefile contains polygonal data. Lets assume, we have polygon A which has self-intersection which means that the edges in this polygon intersect with each other. Lets ...
2
votes
1answer
250 views

How to join attributes of donut polygon to hole polygon in ArcGIS?

First of all I'm completely new to the realm of GIS and ArcGIS. Basically I need a reliable way to determine a donut hole's containing donut for a few hundred thousand polygons (where the donut holes ...
9
votes
1answer
3k views

Polygon label repeated for each tile

I'm using the standalone GeoWebCache to serv tiles from a remote GeoServer. My problem is that the polygon label is added to each one of the tiles served, instead of only once in the polygon centroid. ...
2
votes
2answers
641 views

Creating Long & Lat for Polygons

I have a base map image with micro regions, however in the attribute table there is no information regarding the long & lat. Is there a way I can create a long & lat for each micro region? ...
3
votes
1answer
322 views

ESRI/ArcGIS draw protractor

I am using ArcGIS maps and trying to follow JS API. I am trying to understand how can I add a protractor on the map which will help in angles while drawing polygons. I understand I could add a Feature ...
3
votes
3answers
1k views

How to clip polygons with a fishnet layer?

I have a layer with multiple polygons (input) and a fishnet layer in polygon (clip layer). I want to clip the multiple polygons with the fishnet to be able to calculate how big portion of the input ...
3
votes
1answer
2k views

How do you convert raster to polygon while avoiding small polygons

I intend to convert a raster to several polygons, but I want to ignore too small polygons, and just keep larger polygon. How can I do that? Thanks in advance!