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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4
votes
2answers
146 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
614 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 ...
13
votes
4answers
11k 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
419 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
531 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
759 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
vote
0answers
365 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
647 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
62 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 ...
4
votes
3answers
3k 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); } ...
2
votes
2answers
4k 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. ...
2
votes
1answer
1k views

How to fetch polygons from PostGIS into a PHP array?

Currently I fetch polygons from a database table using ST_AsText(). The results are in text format, like this: POLYGON((84 104,212 48,321 122,243 179,275 238,131 240,84 104)) I am not quite sure if ...
2
votes
2answers
4k views

Find and list all polygons that overlap with another polygon

I am working with two polygon layers which overlap but are unrelated (one is congressional district boundaries, the other is MPO area boundaries). I would like to generate a list of all the ...
5
votes
4answers
879 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 ...
0
votes
2answers
2k views

Cannot insert simple geometry data

I installed PostgreSQL 9.2.4 and PostGIS 2.0.3 on my Windows 8 machine. Then I created a table using phpPgAdmin and added a geometry column using the following statement. SELECT ...
0
votes
1answer
7k views

Merge attribute of points into a polygon : Arcmap 10

I have points layer which the attribute looks like this: FID Shape ID Lat Long 0 Point 2065 -5.51666 106.48333 1 Point 2319 21.93333 120.73366 I also have polygons layer : FID Shape ...
1
vote
3answers
4k views

Openlayers vector feature coordinates are not transforming,

I have a OpenLayers vector with a single feature [0]. It's coordinates are in the map projection (EPSG:3413) and I want them in WGS84 (EPSG:4326) decimal degrees. I have the following code which ...
17
votes
3answers
5k views

How to find the maximum-area-rectangle inside a convex polygon?

In this post we are looking for algorithms / ideas on how to find the maximum-area-rectangle inside a convex polygon. In the following figure, numbers are the areas of the fitted rectangles. As shown ...
1
vote
0answers
63 views

Are polygons created in Arcpy built in any order?

My script uses a search cursor to evaluate polyline coordinates and build polygons based on those coordinates. The script works well, but I am curious as to whether anyone knows the order (if there ...
3
votes
1answer
445 views

Masking/removing polygons from shapefile

I have a shapefile containing the road traffic noise of a city. The shapefile has 5 columns, where 'noise_in' (noise interval) ranging from 1-5 is included. I want to remove/mask the road noise from ...
0
votes
1answer
529 views

OpenLayers generate random polygon

I have a world map. I need randomly to generate polygons and render them on map. I have no problem with rendering, but can anybody suggest how to generate polygons with random geometry? (I need n ...
3
votes
1answer
192 views

How can I check if a multipolygon can be represented as a simple polygon?

I have a large (30m+ records) spatial data set I have imported into a PostGIS database. I did not expect to find multipolygons in the data set, but it does have a few of them. I'd like to take a ...
3
votes
1answer
402 views

How to determine the longest side of a polygon in QGIS?

Is there a possibility to determine the longest side of a polygon with QGIS? As I need to do that for hundreds of polygons I would prefer an automized method (like a plugin). So far my idea was: ...
1
vote
1answer
173 views

Polygon Nodes do not have separate coordinates [duplicate]

I'm attempting to measure the distance of a series of points from a smaller number of polygons. As a first step, I've changed the polygons into points along their border, via the Vector> Geometry ...
3
votes
1answer
3k views

Problems converting polygon to point [closed]

I'm trying to convert polygons to points with ArcGIS 10. My polygon layer has 2 attributes that I want to give to my point layer. I'm using the Feature to Point function from the Arctoolbox, but it ...
3
votes
1answer
6k views

How to combine (join?) two overlapping polygons to determine combined area they cover?

How do I combine (join?) two overlapping polygons to determine the combined area they cover in ArcGIS 10? I am sure the Geoprocessing tools can do it, but just how eludes me.
1
vote
1answer
619 views

Aggregate points with same values to polygons

I have a shapefile with 2M measurement points (each measurement point has a resolution of a 1/10). How can I aggregate points around each other if and create polygons out of it? They do not have to ...
2
votes
3answers
445 views

How to minimize the number of nodes in a polygon?

I'm building a web application that will be transferring polygons from server to client. Initially, the shapefile is coming from an external source that I have no control over. Often, I find polygons ...
2
votes
1answer
387 views

Evaluate minimum points required to define polygons based on an error threshold

I need to build a model or write an algorithm to do this, which I would like you to share your ideas with me. here is my cadastral problem: I have plenty of polygons and I need to make a report of ...
1
vote
0answers
639 views

Line to Polygon via Polygonizer in QGIS

My question is in the same vein as this one. I'm attempting to convert precipitation lines (Precipitación Media Anual) to a polygon for Mexico in QGIS using the Polygonizer plugin. After running the ...
0
votes
0answers
230 views

Offset a Polygon defined in Lat Lng points by a given distance of miles or km

I am trying apply a positive offset/buffer (enlarge a shape equally from the borders) to a polygon that is made up of a series of latitude/longitude coordinates by a distance that is defined in either ...
3
votes
1answer
541 views

Convert polygons to a number of randomly located points based on polygon size

ArcMap 10.1 on a PC. Working with a large shapefile with ~50,000 poygons with a wide range of size from 1,000+m. to <1m. I would like to convert these polygons into points so I can do some analysis ...
1
vote
0answers
407 views

How can I move two layers at once in QGIS?

I'm trying to move two digitized layers, one containing points, the other polygons to a different location at the same time. QGIS doens't seem to allow this. Even if I select both layers and features ...
3
votes
3answers
2k views

How to make mapable geo data from a solid jpg/png

I have a bunch of hardiness zones, as you can see here: http://mangoly.herokuapp.com/workroom/googlemaps/zones/ They are solid colored PNG images. I know the geo coordinates of the bottom left hand ...
1
vote
1answer
762 views

matching a border of one polygon to another [duplicate]

I have a polygon (A) that I drew the eastern border of in QGIS. I have another polygon(B) whose western border I want to nest against the eastern border of polygon a so they are touching but not ...
2
votes
0answers
184 views

Matching points in table to polygons

this is my first post to this forum. I hope to start participating actively. I have a table with several records (aprox 200.000), each with its own coordinates. And I need to identify the "Polygon" ...
0
votes
1answer
2k views

How to label each polygon in a layer?

QGIS 1.8.0 Mac OS 10.6.8: I want to label each polygon in a layer in a similar way to this image (done in WP Presentations) and am totally confused by the manual. Obviously I have to find a list of ...
1
vote
0answers
158 views

graduated pattern polygon fill

I'm sure this question is really really basic but I appeal to you because I hate the idea that I have spent 20 minutes trying to do such a simple thing... All I want to do is style a polygon layer by ...
6
votes
3answers
19k views

Converting multiple lines into single line using ArcGIS Desktop?

I've no idea if this is basic or what but I have this data that contains multiple lines (forming a polygon shape). I want to convert those lines (multiple - each with a start and end point) to a ...
4
votes
1answer
529 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 ...
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 ...
0
votes
1answer
109 views

Selecting a Polygon based on the location of a point

Currently I have a polygon layer made up of three shapes. All the shapes are listed in the attribute table. One of these three shapes intersects a point. I would like to select just the shape that has ...
7
votes
3answers
1k views

maximum circle inside an irregular polygon from a random point

I am trying to work out an algorithm for creating the maximum radius circle within an irregular polygon (a census tract) based on a given center of the circle. The motivation for this is to obscure ...
5
votes
3answers
477 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 ...
0
votes
2answers
104 views

Why is polygon used as range in GIS and maps?

I am enroute to create an app that finds nearest venues. I already have another SO question on this regard. I don't have any experience with such features, and some of the concepts are not being very ...
0
votes
1answer
5k views

How to create polygon with DBGeography Class in Csharp

I want to create a polygon with csharp 4.5 via DBGeometry class. I found example on csharp to create a point via System.Data.Spatial namespace. (Requires Reference System.Data.Entity) This code is ...
1
vote
1answer
136 views

Split polygons and extract points

I have a polygon file with 90 adjacent polygons. I also have a lat/long point file that overlaps the entire surface of the polygon file (170,000 points). My problem is that working with all of the ...
0
votes
1answer
425 views

Using the ArcGIS Runtime SDK for C# is there a method to Hit Test for a polygon on the graphics layer?

I am very new to using ArcGIS runtime SDK for C#. I have loaded a polygon from a shapefile. I wish to query if a lat/long point is inside or outside the polygon? How can I do this? Thanks in ...
6
votes
3answers
3k views

Creating square grid polygon shapefile with Python?

I have the following coordinates minx, maxx, miny ,maxy = 448262.080078, 450360.750122, 6262492.020081, 6262938.950073 I wish to create a square grid of size 1 m using python. import math ...
2
votes
1answer
266 views

Convex Quadrilateral Polygons subdivision in equal parts using Python / OGR

Consider an irregular polygon (P) which has four vertices. I would like to subdivide P into smaller polygons as shown here http://i.stack.imgur.com/4SKhB.jpg In the old days I was using ArcGIS 9.3 ...