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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0answers
246 views

Divide polygon evenly based on lines and intersection points

I have this purple polygon illustrated in the figure below. I would like to split the polygon so that each line segment (green) split the polygon evenly with the surrounding line segments. A line ...
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1answer
228 views

Sum of point attributes inside hexagons using QgiS UI

I'm very new to Qgis so I would very much appreciate any help you can give me. I have a point shapefile that corresponds to locations of animals captured. I've joined a table to this shapefile with ...
0
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1answer
77 views

How can I know the number of polygons in a selected area in QGIS

How can I know the number of polygons in a selected area in QGIS? Can I use the Select features tool? How can I use? Thank you
1
vote
1answer
199 views

Aggregating a raster to fit a polygon grid

I am working at the scale of 10 square km grid cells for the UK, and have a polygon layer of the Ordnance Survey 10k grid cells in ArcGIS. I have another layer of the human footprint index, also for ...
4
votes
1answer
1k views

How to add CSV data with no coordinates to a polygon layer in QGIS?

I would like to add attributes from an spss database (around 300 cases) to a polygon layer in QGIS. Both datasets have a column with unique IDs. I exported the spss data to a CSV file which does not ...
0
votes
1answer
100 views

Can this compilation and display of species frequency data be improved? QGIS 1.8.0

As a newbie on QGIS, I would like to find out if the way I put a species frequency map together could be improved upon. I had to map the presence or absence of 7 plant species surveyed in 30 2m x 2m ...
6
votes
1answer
1k views

Identify polygon overlaps within single shapefile

Using either QGIS (1.9) or ArcInfo (9.3.1) I'm trying to identify unique overlaps of prehistoric building footprints from an archaeological site recorded within a single polygon shapefile. While the ...
0
votes
4answers
187 views

How can I calculate different polygons by different attributes?

I'm doing my master thesis and want to calculate different polygons (in QGIS 1.8 for Mac) in four different columns which I defined by different attributes. i.e. some of the attributes in the first ...
0
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0answers
80 views

Tiles cover Polygon on zoom and move

i'm using OpenLayers.Geometry.Polygon.createRegularPolygon to generate some nice circles. After i draw them to the Map i'm Moving them and after some while they where hiding by some tiles. The circle ...
0
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0answers
126 views

How to create sector figure in ArcObject?

How to create sector in ArcObject 10.1? Now I draw one point, two lines, two arks. But I think it is not good. It is differents objects. I need one object. Well. Now I drawing: IElementCollection ...
0
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1answer
323 views

How to find and quantify duplicate vertices on a polygon/polyline in ArcGIS 10.0

I need to clean up topological errors in various shapefiles and databases. I did read that the Repair Geometry tool could clean duplicate vertices but how can I know the number of errors before and ...
5
votes
3answers
8k views

QGis: Merge intersecting polygons into one which are part of the same feature

I'm not a GIS professional so I hope I use the correct wording, at least I hope you understand my question. Let's say there are 5 polygons in the feature A. In the shape file there are more ...
4
votes
2answers
717 views

How do I find the average distance within a polygon to a point?

For my purposes, I can assume a homogeneous distribution of points within the polygon. What I want to find is the average distance from points within a polygon to a specified point. I don't know where ...
4
votes
1answer
476 views

Clip polygon and retain data

I have these two polygons: library(sp); library(rgeos); library(maptools) coords1 <- matrix(c(-1.841960, -1.823464, -1.838623, -1.841960, 55.663696, 55.659178, 55.650841, ...
0
votes
1answer
624 views

Reverse geocoding polygon co-ordinates?

I have a large dataset of polygons for property sections that I need to reverse geocode. It was recommended that I use a GIS like Quantam to do this however from my research I am not 100% sure if a ...
2
votes
1answer
211 views

Tools/Script to reshape automaticaly topologic edges within a given distance in ArcGis 10?

I have a footprint feature class and a land use cluster feature class. I am looking for a method/tool/script that would allow me: to reshape two edges into one (topologically) to decide at which ...
0
votes
2answers
479 views

Where to find the variables of QgsPolygon and QgsPolyline?

now I want to use QgsPolygon (and Qgspolyline,too) class in python I have a example by using QgsPoint but I don't know how to use in QgsPolygon following is my Qgspoint example feature = ...
1
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2answers
388 views

How to shift polygons by updating their details in R

I have two polygon shapefiles and I want to see to what extent the observed amount of overlap is due to chance. I'd like to randomly move the polygons in one shapefile to new locations, measure the ...
2
votes
1answer
777 views

How to perform a cascaded combine from python script in QGIS?

I'm working with a large dataset, and I need to be able to combine up to 400,000 polygons. I have been using the QgsGeometry::combine(QgsGeometry* geometry) function and simply looping over all ...
4
votes
2answers
866 views

How to average values in a point layer with respect to polygon layer in QGIS?

I am new to GIS and have the following problem: I have 2 layers: a point layer with a column that contains numbers (pollution index from specific measurement point) and a polygon layer with different ...
1
vote
0answers
2k views

How to write a point-in-polygon query for Postgis?

I'm trying to write a query in Postgis which will return all rows where a dynamically changing longitude/latitude point resides within the geometric polygon of that row (in the geom column). This is ...
4
votes
1answer
5k views

Joining polygons in R

I am wondering how to join spatial polygons using R code? I'm working with census data where certain areas change over time and I wish to join the polygons and the corresponding data and simply ...
4
votes
2answers
2k views

How do I get that polygon from Javascript ArcGIS API?

I would like to have a user draw a Polygon (or Line) onto a web map with the Javascript ArcGIS API drawing tools. For the life of me I can't figure out how to pull that polygon from the client and get ...
1
vote
4answers
262 views

Web service to see postgis polygons

Is there any website or web service where I throw a polygon postgis and he show me on the map this polygon. Example: I put this POLYGON((0 0, 1 0, 1 1, 0 1, 0 0)) and the service show me the ...
0
votes
1answer
163 views

QGIS create point data attribute as the name of the polygon it falls in

I'm working in QGIS with a point data set overlaying a farm with 140 fields. While I can analyse the points from each field individually, I would rather use an awk script to calculate statistics I ...
3
votes
3answers
265 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
133 views

How to paste pictures into data frame?

I have a polygon feature class and I want to trace (select with a polygon) a picture that is solely comprised of a couple of interlocking letters. In ArcMap when I would do this I would simply drag ...
5
votes
1answer
814 views

How to Create Touching Multi-Part Polygons?

I have a set of parcels as illustrated in the image below. There are currently no multi-part features in dataset. What I would like to do is to merge (not the right word) all of the parcels with same ...
1
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2answers
1k views

How to convert self intersecting polygon to multipolygon?

Working with the union and polygonize methods in GDAL/OGR, I often end up with self intersecting polygons. The case is one polygon which essentially consists of two polygons: In the above example, ...
1
vote
1answer
153 views

Remove parts of line that fall within a polygon

I have a polygon and two lines. How can I remove the portion of each line that falls within the polygon? # polygon coords <- matrix(c(-1.798123, -1.793072, -1.805767, -1.804129, -1.798123, ...
3
votes
2answers
261 views

Detecting ring direction of a polygon using ArcPy

I am using ArcPy in ArcGIS 10.1 to process some geometry using the arcpy.da data access module. However I have run into a problem with complex Polygons that contain inner rings/holes. From the ...
1
vote
0answers
250 views

Commit Feature WPS Split process

I develop a WebGIS application with GeoServer (2.1.1) and GeoExt (with the last version of OL). Data (polygons features) are stored in a postgis DB. I've implemented editing tools that allow users to ...
1
vote
1answer
4k views

Control view of Multi polygon in Google map

We have multipolygon WKT. We have no issue to draw all of them in Google map. Below are the codes. The only issue is that we want only the first polygon to be visible but the rest to transparent. How ...
1
vote
1answer
77 views

For each polygon, return yes/no value if it intersects another layer

I have a polygon grid overlaying several other polygon vectors. I wish to visit each polygon in the grid and ask yes/no if each of these layers fall within the grid cell or not. I can do this easily ...
13
votes
2answers
2k views

How to speed up the plotting of polygons in R?

I want to plot the country borders of North America over a raster image depicting some variable and then overlay contours on top of the plot using R. I have been successful in doing this using base ...
2
votes
0answers
250 views

Divide polygon layer by point layer in QGIS?

I have two layers - one polygon layer that is a buffer of a road layer, and one point layer that shows certain locations along that road. What I want to do is to divide/split the polygon layer at the ...
0
votes
1answer
344 views

Knowing the polygon id and getting the extent [duplicate]

I have a text box where I have the polygon Id like, "id_of_the_polygon_12345". Is it possible to get its extent and zoom onto it? I have figured out how to do it upon clicking on the map. But could ...
0
votes
2answers
880 views

How to scale/reduce my polygon without changing the central lat & long?

I am writing a VBA code to resize my polygon, I get a input as vector points(Shape file). The code below resizes it as according to my scale factor but my central latitude and longitude are also ...
0
votes
2answers
122 views

Zooming into a particular polygon

I am getting the polygon id by doing identifyParams.geometry = evt.mapPoint; identifyParams.mapExtent = map.extent; identifyTask.execute(identifyParams, function(result) { var i; var ...
4
votes
2answers
143 views

“GIS” Mapping on Monument - Scaling

I have a Baroque tombstone for which I have to map the damage phenoma. Normally one can use a vector drawing programm but one has always two boundaries between the different polygons. Questions: Is it ...
8
votes
1answer
408 views

How to automatically reduce polygon size?

I am working with two polygon layers (counties & states) which I will 'intersect' to find which counties are within which states. Due to data inaccuracies I have to change all county polygons and ...
10
votes
4answers
7k views

How to insert a GeoJSON polygon into a PostGIS table?

I need to insert a polygon from GeoJSON to my PostGIS table. This is how the SQL query looks like. INSERT INTO tablename (name, polygon) VALUES ( 'Name', ST_GeomFromGeoJSON ( { ...
4
votes
1answer
356 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 ...
2
votes
0answers
441 views

Clipped raster leaks outside polygons

I am trying to clip a raster (DEM) with a polygon layer in ArcGIS10.1, using Data Management>>Raster>>Clip. Basically the clipped raster has many pixels outside the polygon boundary, mainly for thin ...
5
votes
2answers
592 views

inner convex-hulls in a set of 2D points

A set of 2D Points are scattered randomly (i.e., no specified pattern), we are interested in finding all inner-convex-hulls (ICH) in an order of largest in area to a minimum until the entire study ...
1
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0answers
281 views

Point Within, Query in a buffer polygon in WMS like in ArcGIS ESRI

I need to do a query to filter the result inside a polygon or geometry, like this: http://help.arcgis.com/en/webapi/javascript/arcgis/jssamples/query_buffer.html But, i need to do this in a opengeo ...
1
vote
1answer
485 views

Polygon to fill gap

Using postgis I want to fill a gap between other polygons. Can you help with some directions what functions to use ? Thank you and sorry if the question is rather noobish. Image to explain from ...
1
vote
2answers
54 views

Field within a Field - Donut Parcel?

Firstly, apologies as I'm a newbie and have only been studying GIS for a few months. I am digitising field boundaries and have a field within a field, and am wondering what the best way of ...
3
votes
3answers
2k views

How to add a polygon from PostGIS ST_AsGeoJSON into Leaflet?

I try to use the following function to add polygons to my Leaflet map. function polygon(geojson) { alert(geojson); // alert for testing layer = L.geoJson(geojson); layer.addTo(map); } ...
1
vote
2answers
2k views

Dividing polygon with another polygon? [closed]

I am working in ArcMap 10. I am trying to divide a polygon with another polygon. I don´t want to clip any part away, but only to divide the polygon? The polygons are stored in two different layers. ...