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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448 views

Need an Algorithm to Determining Polygon Borders

I'm currently writing a program in Java and I'm dealing with polygon objects. I want to create a different color border between touching objects depending on their class (i.e. land, ocean, etc). I ...
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2answers
142 views

Calculating edge length of polygon within overlapping polygon

I have a layer of wetland polygons and a layer of lakes. I basically want to find the total length of lake shoreline contained within each wetland and add these values as an attribute of the wetlands. ...
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1answer
407 views

Create MultiPolygon from QgsGeometry.fromMultiPolygon

I have a list of polygons' points like [[x1,y1],[x2,y2],[x3,y3],[x4,y4]] [[x5,y5],[x6,y6],[x7,y7].[x8,y8]] now I want to create multipolygon from it by using feature = QgsFeature() ...
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1answer
768 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 ...
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1answer
1k views

Create a new vector layer that fills space between other polygons in QGIS

I inherited a clipped (500m radius) land cover map containing vector layers of different land cover categories such as buildings, grass, roads, etc from a colleague. The empty (white) space in ...
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2answers
1k views

How to enclose clustered points with polygon?

I have a raster with forest (1), no forest (2) data. "1" is represent single/few trees and there is gaps between them. I want to create a polygon around these trees to a forest map. It is not a dense ...
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3answers
2k views

How to interpolate into polygons?

I need to interpolate values from points to polygons. I have a point shapefile and a shapefile of adjacent polygons. Some polygons get several points falling inside, some have nothing. I thought ...
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2answers
3k views

Removing sliver polygons in ArcGIS Desktop?

I unioned 2 layers into 1 layer, and it created sliver polygons. I used the elimination tool to merge them with neighboring polygons. As as result, it merges all sliver polygons to only one polygon ...
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1answer
1k views

How to create a polygon from other polygon boundaries?

I want to write an algorithm that creates a polygon inside a hole made by a set of other polygons. It's something like a flood fill and it's like the "boundary" tool in Autocad. The image shows an ...
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4answers
644 views

How to computational efficiently check if there are any overlapping polygons in a group of polygons?

I need to do some processing with groups of polygons. If any of the polygons in the group overlaps other polygon the result is unpredictable and don't throw any error. So, I need to detect if there is ...
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2answers
2k views

Tips for minimizing shapefile size without compromising geographical detail?

I work for a state government's fisheries service, and lately we've been digitizing a lot of our regulatory boundaries within the state's waters that we'd like to service out on web maps. ...
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2answers
885 views

How to combine data from overlapping polygons?

Here's what I'm working with: Shapefile of the current 32 Congressional districts for all states Shapefile of the tract boundaries for Texas A DBF format table of Hispanic counts and proportions for ...
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1answer
103 views

How do you edit a stack of polygons simultaneously?

Using ArcMap 10.1. Lets say you have 100 polygons that all are in the exact same shape and in the exact same place. They appear to be one polygon. How would you edit the shape of all 100 at the same ...
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votes
2answers
683 views

Rgeos drops associated values when intersecting polygons

I am trying to intersect two SpatialPolygonsDataFrames and get a SpatialPolygonsDataFrame as the result. Unfortunately, using the gIntersection function from rgeos (which works impressively quickly ...
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1answer
2k views

How to calculate polygon area considering slopes?

I am looking for an accurate algorithm or a service to calculate surface area on earth where points are calculated on the basis of GPS Coordinates. I am using Google Map Api version 3 and are drawing ...
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2answers
284 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
76 views

Geographic locators within Polygons

I have a list of geographic locators and a boundary file. In QGIS, is there any way merging them together to create a lookup saying this boundary contains these locators? Not the number the actual ...
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1answer
197 views

How can I increase performance on inserting features with polygon geometry?

I have a problem when inserting features with polygon feature class in FGDB. This is my code: ... initialising some fields (does not affect performance) m_featureBuffer.Shape = ...
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1answer
1k views

Export selected raster cells to polygon

I have selected certain values in a raster (roughly 1000 cells), and would like to export them to be able to create a polygon. Converting it to points first then to polygons does not work. Can anyone ...
5
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1answer
259 views

algorithm for displaying holes in a polygon by translating it into several hole-less polygons?

I'd like to plot polygons with holes on a framework that doesn't support holes. The approach to me seems to be to translate the single polygon into several ones adding up to the whole polygon, leaving ...
5
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1answer
188 views

Create raster with grid cells values based on area covered by polygons

I have a polygon data with area covered by the forests (data is here - https://www.dropbox.com/s/zgckliydalljw6a/sp_data.zip?dl=0). I want to convert polygons to raster. The value of each grid cell ...
5
votes
1answer
573 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 ...
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3answers
376 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 ...
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1answer
1k views

How to automate the drawing of polygons (square) around a number of points in QGIS?

In QGIS (or alternatively any other scripting + GIS stack), how can I automate drawing a 100km x 100km square around a number of points, with the point being dead in the center? I'd need to loop ...
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0answers
97 views

Split polygon by area using ArcGIS for Desktop (or QGIS)? [duplicate]

I'm interested to split a larger, irregular polygon into smaller ones. I know the area of the resulting polygon, and I know that the line I want to split it by should be parallel to one of the sides ...
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0answers
78 views

Is there a limit to the number of polygon points you can export to CSV in QGIS 2.4?

Using QGIS 2.4 I am currently importing a csv file with ~30,000 polygons (polygons in WKT format). I also have a United States shapefile. I have used the Clip function to get only the polygons that ...
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0answers
162 views

Find and destroy duplicate OSM multipolygon/polygons in TileMill/PostGIS

In OpenStreetMap there are sometimes multipolygons where attributes are present on both the polygon and the multipolygon relation, such as the Grampians National Park: ...
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3answers
621 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 ...
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0answers
466 views

Grouping analysis of points to divide a polygon into n number of sub-regions

I'm attempting to create n sub-regions from a polygon based on a cluster analysis of a bunch of overlapping raster layers (physical layers, eg: depth, currents, waves). Briefly, I can create a ...
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0answers
193 views

How to rotate polygon to find best fit in Mapnik? [closed]

I have a quite simple problem but somehow I just fail to solve it. There is a polygon and a range xsize and ysize. The x and y size determines the mapnik generated image. The polygon should now be ...
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0answers
343 views

How to write a script to square polygon corners?

I'm looking for a script that will square the corners of polygons that are near 90 degrees but not exactly. Near could be dealt with via a variable, for example within 5 degrees of 90 (85 - 95 ...
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5answers
2k views

Simplify shapefile parcel layer

I have a very large shapefile with over a million parcels within it. The problem I am having is that the polygons representing each parcel are very jagged. What I am looking for is a simple and fast ...
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3answers
3k views

How to export polygon coordinates to CSV (not WKT)?

I am new to QGIS, and I am now trying to export polygon coordinates from a shape file to a csv file, but so far all my attempts have failed. I have found numerous questions and answers about this, but ...
4
votes
3answers
949 views

How to subtract polygons from polygon?

I have two polygon layers, one is green that represents all non-public right-of-way land. I have another polygon that is just a circle with a specified radius. I would like my output to be a polygon ...
4
votes
2answers
2k views

How to Select “Inverse” of intersection of two polygon layers?

I'm wondering if there's a way to intersect two polygon layers, take the intersection, and remove that from one of the polygon layers, making a new layer out of whatever is left over? Basically, the ...
4
votes
3answers
877 views

Order of polygon vertices in general GIS: clockwise or counterclockwise

Two days ago I asked a question about the internal storing order for the vertices of a polygon in ESRI shapefiles. That question was answered (Are polygons stored clockwise or counterclockwise in a ...
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votes
5answers
26k views

How to connect points with a polyline in ArcMap 10?

I have a layer containing a few hundred points representing a survey track. The points are laid out in chronological order in the corresponding attribute table. How can I have ArcMap 10 automatically ...
4
votes
1answer
4k 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
3answers
171 views

How to shrink polygon on two sides?

I have a polygon which I know is a rectangle, although it may be at any orientation: I want to shrink this polygon by a third of the width from two sides, so that I just get the strip in the middle ...
4
votes
1answer
123 views

What is the best format to encode polygons such as lakes?

I am looking for a standard format to encode polygons, such as lakes, in one file that is easy to create and common so that others can use it in different GIS systems. Every file will contain data on ...
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 ...
4
votes
5answers
1k views

Python loop Polygon to raster not working

I want to convert a large number of different shp polygons to raster in ArcGIS 10.1, using an existing field column "class" for the new raster classes. I am not very fluent in python but I thought ...
4
votes
1answer
1k views

How to find markers in selected dragbox openlayers 3?

Here is a part of code, draw = new ol.interaction.DragBox({ /* dragbox interaction is active only if alt key is pressed */ condition: ol.events.condition.altKeyOnly, ...
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votes
3answers
1k views

Python OGR: convert a point geometry into polygon

I'm writing a routine for creating the convex hull envelop around shapefiles of islands. I could read the data, extract polygons vertices into a geometry and then compute the convex hull. Now I need ...
4
votes
2answers
3k views

Is there an easier way to edit polygons in ArcMap?

I am updating woodlot polygons in ArcMap 10. Instead of editing individual verticies, is there a way to edit that is more like drawing part of a new shape (say if the woodlot has expanded only on one ...
4
votes
1answer
6k views

Create point in intersections of two layers

I have two layers. One of them is 'Road_line' and another one is 'forest_shape'. I want to create a point layer that has points in intersection of that layers. I couldn't find any tools for it.
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3answers
7k 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
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2answers
140 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 ...
4
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3answers
4k views

Openlayers remove previously drawn polygon on starting to draw next one

Objective: At any point of time there SHOULD only be zero/one polygon(s) on a vector layer with a polygon control. I need the previous polygon to be removed as soon as user starts drawing the first ...
4
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4answers
3k views

Remove Polygon Islands

I'm really stumped with the problem. I have a polygon layer with no intersects or holes and I need to remove some 'islands', as defined by attributes of a certain size within the layer. It's a hard ...