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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81 views

Change SHP Projection to display on Google Map

I'm pretty new to GIS but not to programming, so sorry if this was already asked. I didn't find a solution not sure if I didn't quite understand everything about Projections and so on. I have a GIS ...
5
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4answers
1k views

Why doesn't the split tool return any records in the attribute table?

I've been trying to split a large land use shapefile using a set of study area polygons as the split feature, but when the function finally finishes running (the land use dataset is quite large), all ...
0
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2answers
47 views

Count objects in polygons

I have a .txt file containing the coordinate of the two polygons in the picture below as well as coordinates for each of the lines inside the polygons. Could anyone help to count each line inside ...
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1answer
205 views

Draw polygons from an array in OL3

I have an query that produces an array of coordinates like so: 95.61,38.60 95.22,37.98 95.60,37.66 94.97,37.65 (long/lat separated by "," and coordinates separated by a space). How can I use these ...
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0answers
38 views

How to convert points distribution toward surface information?

I'm working with QGIS 2.6 I have a points layer representing different bus and train stops. I applied a categorized symbology; each colour represents a class of value (field regarding time access ...
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1answer
187 views

autocad-map of real estates with own coordinate system and information to be converted to use it in QGIS

I have a question regarding CAD and QGIS, but unfortunately I don't have a clue of CAD. Here it goes: Real estates data has been mapped. There are several reference points surrounding the area. So ...
6
votes
2answers
234 views

Wrong $area from field calculator (QGIS)

The area of the polygons in a layer, calculated by the field calculator with "$area" is wrong (much too big) for some polygons. If I draw the concerned polygon again, the area is calculated correctly. ...
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2answers
95 views

Correlation analysis of two polygon shapefiles with nominal data

I am working on a research- trying to model vegetation types based on factors affecting their distribution. In that case I have observed a strong relation between vegetation and soil types, from just ...
6
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1answer
5k views

can I extract overlap of polygons within the same layer?

I am trying to extract the overlap of polygons that are within the same layer in 10. The layer came from a buffered street centerline and I'm trying to extract and delete the intersections from the ...
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1answer
26 views

How to convert a specific multipolygon to minimum polygons

I've got this kml file with one multipolygon inside. A link for the file are here multipolygon.zip My goal is to get a multipolygon with the minimum count of polygons with only outer border and ...
3
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1answer
42 views

Concentric Ellipses around polygons as a representation of density

I have someone who has given me a thumbnail of a map with some concentric ellipsoids placed in estimated high density locations for our business. One location has three, and two other location have ...
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0answers
49 views

QGIS, How to label a layer in different font sizes, shrink to fit in polygon or a multiple line label?

I am just trying to figure out how to label a polygon layer to fit its size in QGIS. or if its very long title should break in line and scale, i did some research but couldn't find anything helpful is ...
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0answers
30 views

QGIS Partitioning Regions

I have to polygon shapefile maps in QGIS that cover the same area. One with ~90 polygons (call them regions) and the other with about ~800 polygons (call them zones). I want to add a data column in ...
2
votes
4answers
903 views

QGIS Polygon precision

Is there a way to edit the precision of polygon points in QGIS so that each coordinate has the same number of decimal places? For example, the coordinate 23.18273917, -84.29172638491 would be ...
0
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0answers
31 views

QGIS - save vector poly layer into individual shp files? [duplicate]

Using QGIS v2.8.1, I have a directory of GeoTiff images. Using the raster ‘Tile Index’ plug-in (selecting “location” as the file index), I am able to create perfectly matched vector polys that I can ...
4
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4answers
555 views

ArcGis 10 - create polygons as % of original

Could someone help me with the following? I have a polygon shapefile and need to create new polygons, within the originals, as % of original area. I used buffer by field (Field= new area as %) but the ...
10
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3answers
5k views

How to merge two 'incompatible' polygon layers in ArcGIS?

I have two layers of polygons with administrative boundaries. Although they come from the same data provider, they seem to have small discrepancies and do not 'fit' each other. How could I merge ...
3
votes
3answers
506 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 ...
12
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4answers
1k views

Grouping corner-touching contiguous polygons using ArcGIS Desktop?

Using ArcGIS 10, I have a Feature Class which I converted from a Raster (GRID) (Raster To Polygon Tool). There are approx. 180,000 polygons. The attribute table contains a [grid_code] field which ...
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1answer
107 views

dissolve polygons of GeoJSON with gdal/ogr

I have a GeoJSON with only polygons in it. I have to dissolve (merge) the polygons with the same "DN"-value. I found out that you can do it with shapefiles like this: ogr2ogr outputfile.shp ...
9
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4answers
6k 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 ( { ...
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2answers
70 views

how to color polygons with random color in QGIS

I have a map with a large number of polygons that I want to colour individually for display purposes. There is not particular pattern required, only to present them as individual catchments in a ...
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1answer
29 views

Get Raster Values from a Polygon Overlay in ArcGIS

I have the same problem as Curlew in Get Raster Values from a Polygon Overlay in Opensource GIS Solutions and thecrashlandingdodo in Step-by-step: How do I extract Raster values from Polygon overlay ...
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1answer
37 views

Euclidean distance outside a Polygon (ArcMap)

I got some university coursework to analyse the best potential areas for a residential development project and I'm currently doing multi-criteria evaluation. One of the shapefiles in the dataset given ...
0
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1answer
48 views

Sampling one shapefile with polygons of another using R?

I have two shapefiles that partially overlap. One (the bigger one) consists of several polygons which represent fields I am interested in. The second, is a rectangular shape that overlaps about 30% of ...
0
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1answer
39 views

Copying attributes of one row to another row in polygon shapefile in ArcGIS?

I have a single polygon shape file in ArcMap with 25*25m grids, and I want to assign the attribute values of a single grid/polygon to another one close by i.e. copy attributes from a row to another ...
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0answers
179 views

API to find polygon for cities and administrative boundaries in India

I am new to GIS and learning basics by going through various forums. I am looking for a way to get polygon coordinates for any place (city, 2nd/3rd order administrative division) in India. I started ...
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votes
2answers
1k views

Openlayers Vector Layer Polygons not displaying properly with OSM

I have an Openlayers map displaying Acetate tiles in OSM, and I'm drawing polygon regions on a vector layer to represent the countries of the world. This works fine for the most part, however, there ...
0
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1answer
38 views

ggplot2 plots polygons with wrong topologies

I'm trying to plot polygons in R using ggplot2. In GRASS, QGIS and normal R the map renders fine, but ggplot2 seems to have some kind of topological difficultes I can't explain. With normal R it looks ...
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1answer
28 views

polygon neighbors

Could you please tell me how to check in ArcObjects same feature overlapping other feature like (Building OID 10 and Another building OID 11) i tried to like below code but i am not going to for other ...
3
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0answers
51 views

Adjacency matrix for polygons using Java

I am trying to create an adjacency matrix from a set of polygons. That is, I have a bunch of polygons and I want to identify which polygons have a common edge or "touch" each other. Once I find this ...
1
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1answer
91 views

CAD line drawing to GIS polygons pt II

I'm a (reasonably) proficient GIS user (mostly QGIS, but some Arc GIS) who has been thrown the conundrum of converting/importing CAD urban planning drawings (2D drawings produce in AutoCAD 2014) to ...
4
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1answer
135 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):= ...
0
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1answer
118 views

QGIS: How to add a second polygon that is exactly 5km larger in all directions?

Given is a map with an airport. Within a distance of 5km around the runway there is a so called no fly zone for drones (in Switzerland). I want to show this zone in a map. What I would like to do is ...
0
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1answer
68 views

How to merge polygons with ST_union

I have a similar problem, but I can't get the syntax correct. This refers to the following question: Merge polygons in CartoDB? I'm trying to merge multiple polygons into one (in this case, just ...
2
votes
2answers
179 views

A library to edit geometry in C#

For my windows application, I am looking for a method to edit vertexes and geometry of features that are stored in a SQL Server database. I just want a simple function for dividing polygons into 3 ...
0
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0answers
76 views

polygon shapefile R extract issues

I'm trying to do simple RF classification in R based on https://gis.stackexchange.com/a/39103/48810. The code I am using is as follows: require(sp) require(rgdal) require(raster) ...
3
votes
3answers
1k views

How to clip polygons with a fishnet layer?

I have a layer with multiple polygons (input) and a fishnet layer in polygon (clip layer). I want to clip the multiple polygons with the fishnet to be able to calculate how big portion of the input ...
1
vote
1answer
100 views

CAD line drawing to GIS polygons

I'm a (reasonably) proficient GIS user (mostly QGIS, but some Arc GIS) who has been thrown the conundrum of converting/importing CAD urban planning drawings (2D drawings produce in AutoCAD 2014) to ...
10
votes
6answers
2k views

Where can I get neighborhood boundaries?

Besides Zillow's creative-commons licensed neighborhood boundaries shapefiles, what sources of neighborhood boundaries are there? Not just in the US, but all over the world. Free/open source is ...
2
votes
1answer
114 views

Polygon centroid coordinates update error

After a week of unsuccessful fighting I'm forced to ask for your help. I have created a table 't_excavations' with fields 'id_excavation', 'geom' (MULTIPOLYGONE), 'longitude', 'latitude' CREATE ...
5
votes
1answer
2k views

How to take polygon centroid in Postgis

I have table with column name,Latitude and Longitude.I want to update this with polygon name and its centroid latitude longitude.I know there is a function in postgis st_centroid(geometry). But I want ...
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vote
1answer
55 views

Connecting polygon accidentally deleted - filling in the gap

New QGIS user, Brighton 2.6. I accidentally deleted an elongated (lots of "peninsulas" polygon that represents a stream-based habitat - two gaps on SW boundary and two on the northern boundary ...
0
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1answer
177 views

GeoServer SLD: fill a polygon with color sampled from gradient

I have a "geometry" and a "rating" column. I want to symbolize the geometries in an SLD (PolygonSymbolizer) but fill it with a color value that is interpolated between BLUE-PURPLE-RED based on the ...
1
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0answers
85 views

Create diagonals in polygon with QGIS or ArcGIS

How is it possible to create the diagonals in/of polygons and to calculate the length of this diagonals afterwards. It's for a lot of polygons so maybe a fast/automatic method would be nice. I ...
0
votes
1answer
3k views

Dividing polygon layer into multiple layers by values in attribute table column using ArcGIS for Desktop? [duplicate]

I have polygon layer with multiple types of area (forest, grass, and many more), and I´d like to divide this layer into many layers by the area type. I´ve tried Split function but I receive an error ...
0
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0answers
39 views

Overlay polygons on raster in different projections

I'm overlaying polygons on a raster to get the average value inside the polygon (using SAGA->Shapes-Grid->Add grid values to shapes in the QGIS Processing Toolbox), using a geographic and a ...
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2answers
73 views

Using GDAL to get vertices of a multipolygon

I am successfully using GDAL to get the vertices of a polygon from a ShapeFile using .NET code. This link showed me how to do that: ...
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0answers
40 views

Showing large number of polygons in SpatiaLite on Android map?

I have 2,300 complex multipolygon features in an offline SpatiaLite database. How can I show them on an Android map without slowing the map to a halt?
0
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1answer
57 views

Simplifying polygons in ArcGIS considering contains-one-point topology rule?

I want to simplify polygons using the "Simplify Polygon (Cartography)" tool in ArcGIS 10.2. Additionaly there is one point in each polygon and this condition should still be fulfilled after ...