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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31 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 ...
3
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1answer
67 views

T-shaped polygons

Is there any coefficient that can indicate T-shaped polygons ? Examples of T-shaped polygons :
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1answer
48 views

Identify geographic location to points

I am quite new in QGIS and I really need your help. I have a map of Kenya divided into 68 districts and I have coordinates of 30.000 schools. The points have one variable besides the latitude and ...
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0answers
26 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 . ...
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1answer
54 views

How to select/create polygons of interest based on existing polygon database and indicate other polygons that share boundaries in ArcGIS 10.2

The existing polygon database contains attribute table with the following structure, and has three levels; country, state, and city. I am interested in the state of 'Anhui' for example (and many ...
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1answer
69 views

Using polygon layers to cut holes in other layers

I have a number of polygons in a layer (old rehabilitation areas) and want to be able to selectively bring one to top and use this to cut a hole in the others and fill this with the cutting polygon ...
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2answers
44 views

Polygon Data to Fit Raster

I'm working with an NHD Flowline of streams and rivers in NC, and I'm trying to only retain the ones in the raster. I tried to convert to the raster to a polygon and was going to clip them, but in the ...
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0answers
35 views

Intersecting Overlapping Polygons Individually in ArcGIS

Map Layers: -Census Tract Shape File w/Population Data -Set of Store Locations with 5 Mile Buffers (Significant Overlap Between Buffers) I have create feature layers for both and I am trying to ...
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2answers
188 views

How to calculate the area between two line shapes?

I'm a newbie using QGIS (2.0). I'm trying to calculate the sidewalk area of a city. For that I have some shapes, extracted from Mricostation, with the topology (facades, fords, fences, etc.), but ...
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1answer
28 views

Non-deletion of nodes in QGIS

I've come across an annoying irritation. I have a .SHP converted from MapInfo which consists of a large number of features, a lot of which are made up of a whole heap of combined/multipart polygons. ...
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0answers
43 views

QGIS - Is it possible to Animate Polygons based on column values? [duplicate]

If you have an number of polygons with numeric data across 4 attributes/columns, you can display the data for one column but can you automatically cycle through the values for other selected columns? ...
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1answer
55 views

Can QGIS report/calculate areas/perimeters of individual polygon components within multipart shapefile?

Can QGIS report/calculate the areas/perimeters of individual polygon components within a multipart shapefile without using the "explode" vector tool to generate a new file? using QGIS 2.2.0 on ...
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1answer
115 views

Calculate distances between polygon centres in QGIS

Is there a practical way to calculate distances between polygon centroids in QGIS? I have a UK city region map divided into administrative units (1 ward = 1 polygon). I want to represent their ...
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1answer
189 views

CartoDB.js - Accessing table fields in hover function

I am new to CartoDB.js and javascript in general, and I am attempting to highlight polygons in response to a mouse hover. My plan of attack attempts to utilize one of the interesting templates ...
2
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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 ...
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2answers
48 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 ...
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1answer
50 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 ...
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1answer
40 views

Add a field to output feature of a geoprocessing tool?

I am running the Watershed tool and RasterToPolygon tool in a loop for a number of points: flowdir = "flow.tif" flowacc = "flowacc.tif" pnts = [arcpy.PointGeometry(arcpy.Point(x=0.0, y=0.0, ID = ...
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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 ...
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1answer
144 views

How to spatially join polygon fields onto a point layer in QGIS?

I have gridded depth points in CSV format that I'm trying to add other map data to, in additional columns. I've tried joining fields, hoping that I could link the Shapefile data to the csv, but when I ...
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1answer
113 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 ...
0
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1answer
54 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 ...
2
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1answer
152 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 ...
3
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0answers
125 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 ...
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0answers
47 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 ...
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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 ...
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0answers
26 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 ...
5
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1answer
370 views

Easily calculate “roundness/compactness” of a polygon

I am trying to find ways to quantitatively describe the shapes of various polygons. For my project, these polygons represent lakes, rivers, lagoons, and parks. So they can be almost any shape. One ...
2
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3answers
160 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 ...
2
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4answers
226 views

UK Postcode boundaries [duplicate]

Before I go and pay is there a free source for UK Postcode Boundaries, ideally down to Postcode Sector level ("AA00 0" or even better "AA00 0A")? Failing that can I generate them in QGIS if I have ...
0
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2answers
71 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 ...
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1answer
184 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 ...
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1answer
37 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 ...
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1answer
46 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 ...
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2answers
64 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 ...
1
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2answers
113 views

Looking for dissolve algorithm for Javascript

I have three adjacent polygons that together make up a larger shape. I need an algorithm that will dissolve the internal borders leaving only the outside border. An example would be a group of ...
0
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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 ...
2
votes
3answers
536 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 ...
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1answer
70 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 ...
2
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1answer
53 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
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0answers
136 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
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0answers
48 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 ...
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1answer
156 views

How can a place a point symbol on the center of a polygon?

I'd like to symbolize polygons with a point at the centroid. Does anyone have suggestions how to accomplish this without creating a new shapefile? I'm using ArcGIS 10.0.
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2answers
140 views

How to change raster cell values within a polygon using QGIS GUI?

I would like to know how to change the values of raster cells which are within a polygon, leaving all cell values outside the polygon unchanged. I would like to subtract 1.5m from each raster cell ...
0
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2answers
101 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
140 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 ...
2
votes
3answers
312 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 ...
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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
92 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
62 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.