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.

learn more… | top users | synonyms

0
votes
1answer
95 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
43 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 ...
1
vote
2answers
47 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
49 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 ...
0
votes
0answers
63 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
1answer
105 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 ...
2
votes
1answer
149 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
votes
1answer
52 views

How to copy closed loop lines into polygon feature class

I'm trying to utilize line contour data to find the volumes of local depressions. To do this, I want to copy the closed loops formed by depression contours into a polygon feature class to find the ...
4
votes
1answer
417 views

How to split a polygon using R

I have an irregular polygon which is a spatial object. I want to divide it into multiple polygons (say, n=25) with equal height. To show how I want to divide it, I've plotted grids on the ...
0
votes
1answer
177 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 ...
3
votes
0answers
124 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 ...
2
votes
3answers
110 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 ...
1
vote
0answers
45 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
vote
0answers
32 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 ...
0
votes
0answers
25 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 ...
2
votes
3answers
157 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 ...
0
votes
2answers
66 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
votes
1answer
22 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 ...
1
vote
1answer
36 views

How to hide grid's labels when zooming out?

I have used polygon grid layer on my map, and I used to label the layer with ID automatically, and the result was convenient for me: But when I zoomed out, the labels didn't hide at all! and they ...
0
votes
1answer
44 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 ...
1
vote
2answers
61 views

How to resample polygon vertices so that they are evenly spaced in Arc 10

I have digitized the outline of many river channels (by both manually picking points and using streaming mode), but now I need the vertices to be evenly spaced (for input to another program). I tried ...
2
votes
3answers
484 views

Clip a raster using a shapefile into multiple rasters?

I have a raster file representing a large area and a shapefile of 30 polygons representing watersheds. I would like to clip the raster with the shapefile to create 30 rasters representing each ...
2
votes
2answers
89 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 ...
2
votes
2answers
148 views

Is there Shape Metrics Toolbox or equivalent for ArcGIS 10?

I need to compute the geometric properties (e.g. contiguity index, dispersion index etc.) of a series of polygons and I would like to use the Shape Metrics Toolbox. I am using ArcGis 10 and the ...
1
vote
1answer
65 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
295 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
52 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 ...
0
votes
0answers
47 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 ...
2
votes
3answers
274 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 ...
7
votes
3answers
835 views

Create a square grid polygon shapefile with python

i have the following coordinates minx,maxx,miny,maxy = 448262.080078, 450360.750122, 6262492.020081, 6262938.950073 i wish to create a square grid of size 1 m using python. import math ...
0
votes
2answers
96 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 ...
3
votes
0answers
134 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
62 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
61 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.
1
vote
2answers
104 views

PostGIS - Select points from a table that exist in a custom polygon

We have a property search site where the user draws a polygon on a map and then the app displays all properties that fall within the polygon. We have properties stored within a Postgres table that ...
1
vote
1answer
65 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
vote
0answers
19 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 ...
1
vote
2answers
41 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. ...
1
vote
2answers
160 views

Integrate grid and polygon of municipalities keeping the biggest municipality per cell with QGIS (or another)

I have a 9x9 grid and a polygon of municipalities of an extensive area of Brazil. My goal is to have a field indicating the biggest municipality per grid cell. I've been trying with intercept without ...
5
votes
1answer
338 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
votes
3answers
356 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
1answer
1k 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. ...
5
votes
3answers
277 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
49 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?
16
votes
4answers
838 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 ...
1
vote
0answers
77 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 ...
1
vote
1answer
56 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 ...
0
votes
1answer
46 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
44 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
227 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 ...