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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3
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1answer
626 views

PostGIS - when I add a polygon, delete overlapping areas in other layers

I'm starting to work with PostGIS and I'd like to solve the following problem: In my database, I have multiple land use class layers, for example: "residential", "industrial", "commercial". The ...
0
votes
0answers
97 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 ...
2
votes
1answer
320 views

Area of polygon split by a line

I need a query that return the area of two polygons that have been split by a line. This is what I did so far: SELECT ST_Area(ST_Split(surface.geom, limite_a.geom)) from surface, limite_a where ...
0
votes
1answer
332 views

Numbering rows and columns in polygon grid (fishnet)

I seem to be a bit stuck on what i thought would be quite straightforward. I've created a fishnet of polygons, all 25 x 25 metres, 100 polygons by 100 polygons. My main task is to create a ...
3
votes
1answer
1k views

How to fill in a ring polygon in QGIS 2.2?

I created a polygon which covers a park. But I want to distinguish some small buildings located inside the park. Consequently, I want to distinguish them and use them as independent patches inside the ...
2
votes
2answers
505 views

Calculate the number of points in a freehand polygon ArcGis Javascript API

I'm drawing a free hand polygon on my map. Now I want to calculate the number of points found in that polygon. I have done this code, which my now is giving me the number of points found in the map ...
2
votes
4answers
2k views

Combining different geometry types into same feature class?

I've searched the question in this blog. Maybe I don't use the right words but anyway my problem is not present in any post so I'll try to explain my question by opening a new one. I have a polygon ...
1
vote
1answer
164 views

How do I add coordinates to a polygon layer to be able to sort the polygons from north to south in QGIS?

I have a polygon file, where each polygon represents one property. I want to be able to sort the polygons from north to south or vice versa. I need them to be sorted in this way when I export them to ...
0
votes
1answer
60 views

Query to create polygone from lines that touches in POSTGIS

I am trying to create polygons from a line layer with a spatial query in postgis the probleme is i dont have a lot of information on the lines only id of each line and geometry thanks for your help
2
votes
1answer
397 views

Batch create fishnet using FME

I want to create a fishnet based on the extent of individual polygons from a list of polygons. I plan on processing each resulting fishnets further. I am maintaining a worldwide data set on Quarter ...
1
vote
2answers
681 views

QGIS Valmiera, Labels only show for part of polygons

Using 2.2.0-Valmiera on Ubuntu 13.10 I have for Croatia 21 Counties as polygons. Labels show only for 12 counties: here I see that no labels are shown for multipart features. So I checked "Show ...
1
vote
1answer
93 views

Get all points with in some range of a point (or range of point) in MySQL

I have got a list of points and a fixed range (10m). So what I have to do is for each point I have to find all the points present in a table with the 10m range of the given point. For example: Let ...
3
votes
1answer
198 views

T-shaped polygons

Is there any coefficient that can indicate T-shaped polygons ? Examples of T-shaped polygons :
2
votes
1answer
80 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 ...
0
votes
1answer
2k 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 ...
0
votes
2answers
73 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 ...
0
votes
1answer
303 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 ...
5
votes
2answers
351 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 ...
0
votes
1answer
83 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. ...
0
votes
1answer
144 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 ...
2
votes
1answer
568 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 ...
1
vote
1answer
1k 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
votes
1answer
201 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
128 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
63 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
1answer
73 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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vote
2answers
2k 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 ...
1
vote
1answer
415 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
votes
1answer
219 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 ...
3
votes
1answer
329 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 ...
2
votes
2answers
763 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
0answers
133 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
43 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 ...
2
votes
0answers
174 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 ...
6
votes
3answers
4k 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
votes
3answers
444 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 ...
5
votes
4answers
2k 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
votes
2answers
288 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
502 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 ...
1
vote
1answer
118 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
79 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
547 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
vote
2answers
993 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
votes
1answer
34 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 ...
5
votes
4answers
4k views

Clip raster using shapefile into multiple rasters using ArcGIS Desktop?

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 ...
1
vote
1answer
1k 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
votes
1answer
62 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 ...
1
vote
0answers
93 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 ...
1
vote
1answer
2k 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.
1
vote
2answers
972 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 ...