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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1answer
413 views

Raster to vector with gaps in Landsat ETM

I need to find size of water area from a raster (jpg) using QGIS 1.8.0-Lisboa. The raster is a Landsat image with gaps of data in it. I used Polygonize, but the output file shows wrong polygon size ...
4
votes
1answer
653 views

Sub-dividing a polygon into smaller polygons

In OpenStreetMap data, some large areas are tagged with a residential=yes tag. Actually within this large polygon there are multiple smaller (rectangular) houses (which are actually not drawn as yet). ...
4
votes
1answer
392 views

Determining if Polygon Contains Negative Space using ArcGIS SOAP Web Service?

I am running queries against a polygon layer using the ArcGIS SOAP Web Service. A user selects a point within that layer and the resulting feature set contains PolygonN objects. Occasionally, the ...
4
votes
1answer
44 views

Find polygons that does not contain (any) polygons with PostGIS

New to PostGIS, I have a polygon layer of water catchment areas which are formed by the specific monitoring points along the river upstream. For example, on one river, there could be multiple areas, ...
4
votes
1answer
67 views

Altering elevation of specific cells in raster layer of QGIS?

I'm looking to alter the height of some cells within a raster and it's been suggested that I do this by creating a polygon layer and use that as a mask to alter only the heights of cells within the ...
4
votes
1answer
57 views

Add column to point data of whether point falls inside polygon

This seems like it should be fairly simple, but have been having quite a bit of trouble. I am no expert in ArcGIS for Desktop I have: one layer of points, and 4 polygons, which partly overlap I can ...
4
votes
3answers
73 views

Google Earth Polygon surface area to follow the curvature of the earth model

Question: When drawing a polygon in Google Earth with latitude, longitude and elevation values at each node, how do you ensure that the surface area of the polygon also represents the desired ...
4
votes
1answer
286 views

Showing Linestring from SQL statement with CartoDB

I have cartodb sql statement to return what polygons are intersected by a linestring, but I'd like to have the linestring visualized over the polygons on the results. Also not add the linestring to ...
4
votes
3answers
311 views

How to compute the outline of multiple tracks?

I have multiple gps tracks with depth data gathered from the lake. The tracks are overlapping/intersecting. I want to get an outline polygon. I have a multi-line shp. I've tried to diffuse it in qgis ...
4
votes
1answer
252 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 ...
4
votes
1answer
515 views

How to delete one polygon from a multi polygon record in a spatialite database using QGIS

I have a spatialite database with multi polygon records within the database. When i try to edit these records i cannot delete just one of the polgons for a specific record. It only allows me to delete ...
4
votes
1answer
349 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 ...
4
votes
1answer
3k views

Arcgis 10: Point layer, polygon line layer, draw points to the nearest polygon point or other nearest line?

I have been using arcGIS for a while now but I often get frustrated with it :( I have version 10.0 arcGIS and I'm have two layers 1) Point data (building locations) 2) a polygon shape file (outline ...
4
votes
3answers
2k views

Calculate neighborhood statistics for polygons?

I've been searching around for the answer to this (including here) and have yet to find it. I'm interested in finding out how to calculate a 'neighborhood sum' for vector, polygon data. I am aware ...
4
votes
1answer
2k views

Create overlapping polygons from contour lines

Working in ArcGIS 10, I have a set of contour lines representing density of commercial square footage, and I have a set of points representing local maxima for each peak of the dataset. For each ...
4
votes
1answer
32 views

How to extract a buffer layer from a vast amount of individual buffers around polygons using ArcMap?

I have a vector layer containing nearly 8000 singlepart polygons. It looks like this: I want statistics on the area that is further than 2,5m away from any border. I thought I could do this by ...
4
votes
1answer
92 views

Remove sliver gaps between polygons with R

Is there a way to eliminate the small "slivers" between polygons using R? The desired solution would create a new SpatialPolygonsDataFrame where the shared boundaries between polygons are coincident. ...
4
votes
1answer
431 views

Edit existing polygons to include several new nodes

I want to define catchments which are quite large from vector contour data. I normally start zoomed out to define the catchment generally as it is easier to see. I then zoom in and refine the ...
4
votes
2answers
786 views

Find all street names or addresses within a polygon

I have a geojson list of lat/long coordinates that make up a custom polygon of a section of my county. Ideally I would like to be able to find all the addresses that are within the polygon boundaries. ...
4
votes
2answers
966 views

How to programmatically delete all inner rings of a polygon layer?

I have many polygon layers, each layer containing many polygons with inner rings. I know that you can delete a ring manually with QGis (Edit -> Delete ring). I need the python equivalent to ...
4
votes
2answers
1k 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 ...
4
votes
2answers
901 views

Converting shapefile to raster: Character attributes

I've got a shapefile that I would like to convert into a raster, but the trick is that the attribute I want a raster version of is character data. I'm familiar with geoprocessing using GDAL (in the ...
4
votes
1answer
303 views

Merge polygon without attribute (in field) with nearest polygon with attribute

In the image you can see districts in BLUE with attributes (name of district) and small pieces in RED. The red polygons belong to the blue and I want to merge them. The RED are only towards the ...
4
votes
1answer
160 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):= ...
4
votes
1answer
772 views

Merging partially overlapping polygons into a table in PostGIS

I have a couple of tables (three) with polygons (landuse coverage in this case). Within each table, there is no overlap, but between tables there might be a lot of overlap. I would like to combine ...
4
votes
1answer
1k 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 ...
4
votes
1answer
2k views

GDAL - creating vector from raster

[SOLVED] Good day! I'm looking at either gdal_contour or gdal_polygonize.py to create a vector layer file from a raster file. I can create the vector file using either method, but it's upside down ...
4
votes
1answer
2k views

Convert shapefile lines to a polygon in GRASS

I have a shapefile of a map that is the outline of a number of islands. I would like to convert the lines into polygons (ie all islands filled in) using GRASS. I searched on how to do this with GRASS ...
4
votes
1answer
59 views

Reshape polygon to boundary of other polygon

I have two polygons. The first one has a white background and brown boundary. To othr has the pink background. how is it possible to reshape to first polygon to the boundary of the other polygon?
4
votes
0answers
60 views

Buffer neighbouring polygons without overlap using QGIS

Is it possible to create a buffer around neighbouring polygons, so that the new polygons do not overlap? Preferably in QGIS but any other tool will do. So instead of the first result I would like ...
4
votes
1answer
79 views

How to find the distance from a point to a polygon, via another point, in R

I am trying to calculate the distances between a central point, and the edge of a polygon, along straight lines drawn between the central point and another set of points (where necessary extended ...
4
votes
1answer
933 views

MongoDB: Search for polygons which have a certain location

Good day :). I am trying to implement a search feature on MongoDB using Mongoose.js , the short version of which is this: I tag locations on a map as polygons. and give them names. Then when an user ...
4
votes
0answers
101 views

Reducing Polygons [closed]

I am merging several data sources into one final answer via a fishnet. My problem is I have landcoverage with multiple attributes unioned to a fishnet. Now I want to eliminate the smaller polygons ...
3
votes
5answers
3k views

Counting road intersections and blocks

I have a shp file that consists of the road system of Mexico City. I would like to count the number of road intersections (crossings) and blocks (which I would define as a segment starting from one ...
3
votes
3answers
2k views

How to clean up a polygon by removing vertices and lines within?

After merging a set of shapefiles I've ended up with polygons that have vertices and lines within them. Is there a simple tool to remove these vertices and clean the polygon in ArcMap 10.2? I realise ...
3
votes
3answers
614 views

Sorting polygons by latitude?

We have a set of polygons which we would like to sort and number according to their latitude. This will make it easier for local authorities to relate to the numbers of the objects. I have looked ...
3
votes
2answers
4k views

How to edit Shapefile Attributes?

How might I go about exporting a polygon shapefile (e.g. CSV) so that attributes (not geometry) are editable by others, and importing it with the changed attributes (of which there are several columns ...
3
votes
3answers
126 views

Where to find a polygon shapefile of countries, states and islands?

As often happens, the hardest part of GIS is to come up with clean shapefile with an attribute table. I need to create a choropleth map, but all I have is this: Domicile,Captives New Zealand,24 ...
3
votes
1answer
5k views

How do I rotate the polygon about an anchor point using python script?

I know there would be no tool in arcpy module as such but mignt have in third party modules. I however tried taking the vertices of the polygon and moving using the below formula. but did not get the ...
3
votes
3answers
1k views

ArcGIS - possible to set the drawing order of polygon features [duplicate]

I have a table with polygons that I wish to display in a map. I would like the smaller polygons to appear on top of larger polygons. Is there a way to set the drawing order such that the larger ...
3
votes
3answers
236 views

Using SVG from Wikipedia to fill polygon?

I'm trying to use the flag of each region in Italy to fill each region's polygon. I have downloaded the shapefile of Administrative areas for Italy from diva-gis and am now attempting to fill each of ...
3
votes
2answers
8k views

How can I display this polygon in Google Maps, properly

NOTE: this question is sorta like a follow-on question to this original GIS Question I asked. In that question, the main suggestion was that I was trying to show two polys. Now, I'm asking about a ...
3
votes
2answers
556 views

Overlaying polygon filled with solid colour with diagonal lines in QGIS

I'm making a vegetation survey map using the UK phase 1 survey colour codes. The code for marshy grassland, for example, is orange overlain with purple diagonal lines. For the moment I've created ...
3
votes
2answers
787 views

Finding points along a path

I am unsure of the best approach to this problem. I can think of some ways of doing it which I will list below but I am looking for the best and most efficient way of doing this. Problem Given a ...
3
votes
2answers
1k views

Generate non-overlapping shapes from a buffer

I have a collection of points, and I need to generate shapes around these points. Let's assume that these points are locations of offices and that the shapes are the 'area of responsibility' around ...
3
votes
2answers
2k views

Merge geojson polygons with WGS84 coordinate

I have a Geojson file with some adjacent polygons and I want to merge them into one. I know it's a recurrent question but I can't find information for polygons with latitude and longitude coordinates ...
3
votes
1answer
153 views

Is there an alternative to the Integrate tool that will not change one of the inputs

I have two polygon layers, and would like to snap the outlines of one of them (colored poly's) to the other (grey) without changing the grey in anyway (so Integrate seems out). It should only snap if ...
3
votes
1answer
2k views

How can I get my Qgis area calculations in metres rather than degrees? My shapefiles are projected using WGS 1984 UTM fuseau 35 Sud

I am using Qgis 1.7.4 to calculate the area of polygons. My shapefiles have been projected using the coordinate system WGS 1984 UTM fuseau 35 Sud, but my area calculations are still displayed in ...
3
votes
3answers
131 views

How can I join two polygons that are within the same layer in QGIS?

I have two polygons in QGIS that are within the same layer and I want to merge them so they are not in two different polygons, which means that the gap between them sould not exist. How do I do that? ...
3
votes
2answers
503 views

Can't transform lines to polygons

I have a similar question to: How to join lines in QGIS for later using "lines to poly"? I have a line shapefile that I wish to transform into a polygon shapefile. After making some ...