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.

learn more… | top users | synonyms

2
votes
2answers
189 views

Finding a point inside a polygon based on maximum value of a specific field

I have a Polygon Shapefile that represents US counties and a Point Shapefile that represents hospitals. The hospital attributes table includes fields like "Number of Beds", "Number of Patients" and ...
3
votes
2answers
3k views

How to subtract Geometry Point Polygons in OpenLayers?

I have two json arrays, one for background polygon and one for other polygon. And from them, I got two polygon layers. backgroundLayer = new OpenLayers.Layer.Vector("Background Layer", {styleMap: ...
1
vote
0answers
160 views

QGIS 2.4.0 doesn't support multiple types of geometry in GML file

I'm testing GML 3.2.1 data according to INSPIRE Data specification (version 3.0). Data for theme Cadastral Parcels shall have both polygon geometry and definition point. When I download data from my ...
15
votes
1answer
6k views

Instantiating spatial polygon without using a shape file in R

So, the usual way we read a shapefile in R is via the maptools package, like this: sfdata <- readShapeSpatial("/path/to/my/shapefile.shp", proj4string=CRS("+proj=longlat")) However, I have a use ...
1
vote
2answers
707 views

Count the number of points in a (multi)polygon in shapely?

I'm using Python, Shapely and Fiona to process some shapefiles. Is there an easy way to count the number of points in a polygon/multipolygon in Shapely and Fiona?
1
vote
1answer
514 views

Convert raster to polygon based on cell value ranges using ArcGIS for Desktop?

I have a floating point-valued raster which I need to convert to polygon as follows Put the cells with VALUE < 0.5 into (a small/the smallest number of) polygons Cells in the range [0.5, 1] into ...
0
votes
1answer
320 views

Add Marker on the polygons' centre using Openlayers?

I have written a code to draw polygon from the WKT format.Now I need to add the marker at its centre. In the following code I have passed the centre and shape in WKT format(extracted from database). ...
4
votes
3answers
409 views

How to count the sides or edges of a polygon?

I wondered if it is possible to determine the number of sides / edges (not vertices) that a polygon has. Imagine the following case. There is a shapefile with 10 polygons. Is there any way to ...
2
votes
2answers
313 views

Separate a polygon in different polygons depending of the distance to another polygon

I have a reference polygon "R", and others polygons (in grey). I want to separate each grey polygon in multiple polygons, depending on the distance to R with different Buffers : - The red line is R ...
3
votes
1answer
653 views

problem with polygon smoothing in R

With R I am looking to smooth my Polygon: inter2.csv code: inter1 <- read.table("c:/inter2.csv", header=TRUE) # add a category (required for later rasterizing/polygonizing) inter1 <- ...
4
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 ...
2
votes
2answers
764 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 ...
4
votes
1answer
303 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 ...
2
votes
1answer
205 views

How to construct a line from points in pyshp?

I am reading a shapefile for a pipeline and what I've noticed is that if I just draw a line from one point to the next (in the order I read them), there will be points where the line terminates, and ...
11
votes
6answers
6k views

How to find the boundary co-ordinates from a given set of co-ordinates

Given a set of coordinates, How do we find the boundary coordinates. <== Figure 1 Given the coordinates in the above set, How can I get the coordinates on the red boundary. Boundary is the polygon ...
2
votes
1answer
90 views

SQL Server equivelent to Arcmap Intersect for polygons?

I have three different sets of GEOMETRY Polygon datasets in SQL Server that completely overlap. I need to create a new dataset that has a polygon for each unique area of the three layers. So ...
4
votes
3answers
317 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 ...
2
votes
1answer
1k views

Why does clipping a line layer using a polygon result in an empty shapefile?

I am using QGIS 2.2.0 and want to clip a line layer (roads) so that only those inside a polygon are shown. When I do this using Vector->Geoprocessing Tools->Clip I only get an empty shapefile as an ...
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 ...
3
votes
1answer
1k views

create polygons and fishnets of specific size and orientation and buffers

I want to study 6 areas in the field and in order to do so I want to divide each one of them into smaller areas/parts. What I would like to do is find an average square or rectangle area surface ...
2
votes
1answer
105 views

Create a custom Identify dialog

How can I check if a point belongs to a polygon? I want to create a custom identify tool with edit option. I am using C# and ArcMap 10. My idea is to click on the polygon (building/park/etc) in ...
2
votes
0answers
219 views

Merge vector layers to fill gaps in QGIS

I have a zip code map which I added per zip code data too (a regional director for each zipcode), and then dissolved the map based on the director attribute. As you may or may not know, zip codes are ...
1
vote
1answer
107 views

Looking for information on methods or algorithms used to calculate centroid from polygons across software

Looking for information on methods or algorithms used to calculate point centroids from polygons across software. ArcGIS uses a "gravity model" but can someone point me to the math or a paper on the ...
1
vote
3answers
121 views

polygons to polygon conversion with attribute name [duplicate]

1) I have a polygon shapefile with 1000 multi-part polygons in it. Each Row of the table is a multipart polygon. 2) I need 1000 shapefiles with 1 multi-part polygon in each. 3) Each output shapefile ...
1
vote
5answers
5k views

How to determine if a polygon is self-intersecting using either ArcPad 8.0 or ArcMap 9.3.1?

I am try to automate a sync replica mxd a nightly basis. The issue I am running into is that in some the of the AXFs (that I get from the users and check-in) have polygons that are self-intersecting ...
2
votes
1answer
119 views

Get feature data from lat long input QGIS

In QGIS, I have a polygon dataset with feature data. I would like to extract data from this dataset using a latitude and longitude. To be more clear, I have a list of 1000 coordinates. I would like ...
2
votes
2answers
186 views

Dissolve tool misses out two polygons

I'm trying to dissolve polygons based on a code number in the attribute table. It all works well, with an exception of two polygons that fail to dissolve - they literally drop out from the output. It ...
0
votes
1answer
887 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 ...
7
votes
2answers
18k views

How to calculate polygon areas and perimeters using QGIS?

Using QGIS, if I load a polygon layer and make a new column, how do I fill that column with the: area of each polygon and another column with length of the perimeter of each polygon?
3
votes
2answers
573 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 ...
4
votes
1answer
576 views

Clipping Line shapefiles within extent of Polygon shape?

My question is an extension of Vertical lines in a polygon shapefile. Kindly refer to that question first. What you shall see there is a method of generating vertical lines with respect to the ...
3
votes
1answer
27 views

Bringing attributes of multiple polygons into other polygons?

I need to absorb multible attributes included in block areas into a number of ploygons. In other words, I need to bring block level data into a number of overlaying polygons. The polygons will absord ...
2
votes
1answer
88 views

Joining QGIS extent table with shapefile

I used QGIS to find the extents of a list of features from a census boundaries shapefile. I used Vector - Research tools - Polygon From Layer Extent, which creates a new shapefile with a table of ...
1
vote
0answers
358 views

Create Polygon with inner polygons from KML or Shapefiles?

I am creating a windows forms application and I want to create a polygon from a KML or Shapefile as a layer on top of a Google Satellite map. Today I am using GMap.NET that got an polygon object but ...
1
vote
2answers
350 views

Vertical lines in a polygon shapefile

I am working with a GIS problem using a single input of a polygon shapefile. Consider an irregular polygon. I want to draw vertical lines across the extent of the polygon at equal spacing. How I ...
0
votes
0answers
708 views

How to convert multipolygons to a single polygon

I have converted a set of gps points to polygon and then using .makevalid() I saved them in sql server.But It converted them to multypolygons.Is there any way to fix this problem and convert them to ...
0
votes
1answer
1k views

Zip code highlighted in google map

When we search for a zip code in Google Maps we get the area highlighted in the map with a dotted border. How is this calculated? How do they know how to draw the polygon? I'm looking at implementing ...
2
votes
2answers
840 views

Iterating polygons on a SpatialPolygonsDataFrame in R with readWKT

I have fetched some data (39 objects) from my PostGIS database and converted this data into a matrix: rs <- dbSendQuery(con, "SELECT ST_AsText(polygon_accumulation) AS ShapeWKT from ...
6
votes
1answer
318 views

Select by location of doughnut hole polygon

I have vectorized the Corine Land class raster and want to select certain classes that are "inside" other classes. How can I select the polygons circled in blue? All the select by location options ...
1
vote
1answer
123 views

Converting rasters to polygons through cell centers

With arcgis, it is possible to convert a raster image to a polygon representing the boundary of the raster using the Raster To Polygon tool. The output polygon will follow the cell edges of the ...
1
vote
0answers
346 views

Convert polygon data into extreme lon/lat coordinates using QGIS

I'm very new to QGIS. I have a shape file of census blocks and want to use the data to plot points within each boundary using Google Maps api. I figure the best way to do this is to find the extreme ...
1
vote
1answer
915 views

StArea() in sqlserver is in which unit?

I have a problem with saving STArea in sqlserver. Here is a query where I get the area of a polygon: select Geometry::STGeomFromText('POLYGON ((51.3386535086000000 31.7951253522000000, ...
9
votes
4answers
13k views

Getting polygons of all countries and ISO-3166-2 subdivisons

In order to do reverse geocoding lookups to find a country (as ISO-3166-1) and the subdivision (as ISO-3166-2) for given coordinates I am looking for a way to get all polygons of all countries and ...
3
votes
1answer
1k views

Converting set of points to polygon using C#?

I want to convert a set of gps ponints to polygon.I used a simple loop to convert it to a WKT and than used makevalid() in sql server and save it in a gemetry column in databasae.Is this way right?or ...
4
votes
2answers
1k 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 ...
2
votes
0answers
175 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 ...
9
votes
2answers
453 views

Creating an “average” polygon

I found this thread in the old ESRI forums with the same type of problem I am facing today. The solution to the problem is explained in little detail and since I am not an expert, I was wondering if ...
1
vote
1answer
96 views

Intersection of triangle and polygon

I have a triangle and an arbitrary polygon lying on the same plane in 3D space. I need to find the fastest way to determine if these two intersect, one is inside the other, or completely separated. At ...
15
votes
3answers
16k views

How to smooth/generalize a polygon in qgis

Is it possible to smooth or generalize a polygon in qgis? Ìs there a plugin available like the generalizer-plugin for lines? I could convert my polygons to lines, smooth them and convert them back to ...
2
votes
1answer
341 views

hiding some “feature”s in GeoJSON file on map

I have geojson file including boundaries of most countries in world. When I clicked on a "feature" (aka country, or polygon) I want to hide it while keep showing the others. because I am planing to ...