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.
0
votes
0answers
42 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 ...
0
votes
0answers
20 views
query for adjacent polygons in GRASS?
i need to create a table of each district in india's adjacent districts.
i found this query but couldnt get it to work for me: SELECT p1.PK_UID, p1.Name FROM Polys p1, Polys p2 WHERE p2.PK_UID=1 AND ...
1
vote
0answers
60 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
1answer
54 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 ...
2
votes
1answer
77 views
In OpenLayers, is there any way to convert polygons to tiles?
I have a OpenLayer map which by enabling a feature by user, a very huge table of polygons (lots of small areas, with information and metadata for each) will appear on the map, which rendering this big ...
0
votes
1answer
144 views
How to draw straight lines inside google map polygon [closed]
I have created a google map using google map javascript API V3. I am drawing number of zipcode polygons. The polygons are of different colors depending upon some condition. Now I want to draw straight ...
4
votes
3answers
213 views
Convert multiple lines into single line
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 ...
0
votes
1answer
93 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 ...
4
votes
3answers
2k views
How do I convert a polygon into a point?
I want to convert polygons into points. I know how it's done in ArcGis and I think this may sound trivial but it's a serious issue :/.
I'll appreciate any hints :)
6
votes
1answer
182 views
QGIS define hexagon area around mapped points
I am using QGIS to map a number of radio antennas (for mobile network).
Once I have the layer of the sites (done), I would like to assign to each site a coverage area (envelope). I could achieve that ...
4
votes
1answer
109 views
MongoDB: Search for polygons which have a certain location
Good day :).
I am trying to implement a search feature on MongoDB using Mongoose.js , the short version of which is this:
I tag locations on a map as polygons. and give them names. Then when an user ...
0
votes
1answer
48 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
43 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
0answers
30 views
How to determine if a line is within a polygon or if it exceeds the polygon boundaries?
So I have a polygon layer and a line layer and a point layer...
Each line goes to the centroid of 1 polygon, some of those lines come from within the same polygon, some come from outside of that ...
0
votes
0answers
30 views
Slicing / Cutting a Polygon / Polygon List based on another geometry
I currently use GeoDjango (GEOS, GDAL, PROJ4), I have rather medium set of polygon data (buildings).
To streamline them to a client efficiently (client has a limited viewport) I only want to send the ...
1
vote
0answers
39 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
224 views
What geometric attributes do polygons possess, and how can these be used to filter features?
Given a polygon featureclass containing many polygons of different sizes and shapes, which geometric attributes (area, perimeter, etc) could be used to filter the polygons? It's probably best to ask ...
2
votes
1answer
135 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 ...
2
votes
1answer
63 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 ...
7
votes
3answers
160 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 ...
0
votes
0answers
38 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 ...
0
votes
2answers
70 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
0answers
105 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
80 views
How to convert a shapefile polygon to raster in C#
Does anybody know a way to convert a polygon (vector) in a shapefile to raster data WITHOUT using ArcGIS Explorer Desktop? Is there a way to do this 'progmatically' in C# (WPF with ArcGIS runtime ...
3
votes
0answers
126 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 ...
0
votes
0answers
11 views
Assigning an area to a geoprocessed polygon [duplicate]
using QGIS
I've geoprocessed a layer using the difference function but the newly created layer still holds the area attributes of the layer I used as the input layer...
ie on my output layer, a tiny ...
2
votes
1answer
58 views
Remove intersect of one polygon from another in R
I am trying to remove the intersect from Poly2 onto Poly1. Below are the coords of the 2 polygons.
> coords1
[,1] [,2]
[1,] 992.0161 7462.531
[2,] 950.1962 7413.532
[3,] 902.3632 ...
7
votes
5answers
5k views
Get boundary of raster image as polygon in ArcGIS 10
I have a rectangular raster image in ArcGIS. My question is: how can I produce a polygon which is just the extent of the raster image? That is, I want to have a polygon layer with a single ...
2
votes
1answer
115 views
R: How can I create a polygon from several polygons and a line?
I have some spatial objects that I want to combine, namely three polygons and a line. The ultimate goal is to create a polygon that I can overlay on an area of a map of administrative divisions of the ...
3
votes
1answer
91 views
Polygon to Raster is taking longer in script than in arcmap
I have a large dataset that I am working with. Basically I have a table with 900,000 records that I join to a geodatabase feature layer, then convert that to a raster.
This process takes a total of ...
6
votes
1answer
46 views
Is there a way to select only a certain polygon for editing?
I have a spatialite data base with 4300 polygons contained within. I wish to be able to edit the polygons but once i have highlighted the Polygon from the attributes table i find it hard to edit the ...
1
vote
0answers
39 views
Avoid rounding of coordinates in pyQgis
If I get the coordinates of a polygon in qgis by
x = geom.asPolygon()
It rounds off the coordinate from i.e.
-27,200,334.86
to
-2.72003e+07
How can I avoid that?
1
vote
0answers
55 views
Is segment of polyline contained in polygon
I am pretty new to arcpy and am slowly learning all its functions. I have a scenario where I am traversing a polyline. I get a start point and an end point on the polyline and form a segment with ...
4
votes
3answers
637 views
OpenStreetMap Neighborhood Boundaries
Is it possible to download neighborhood boundaries from OpenStreetMap? I see on maps that they often indicate neighborhood names; is there a way to retrieve their coordinates and boundary polygon ...
9
votes
4answers
4k views
using shapely: translating between Polygons and MultiPolygons
[EDIT: the solution to this was simply to use OGR to read shapefiles. See geographika's example.]
In an ESRI shapefile, there is no distinction between Polygons and MultiPolygons. Furthermore, there ...
3
votes
1answer
85 views
How to make survey lines within a polygon?
I am trying to figure out how to make survey lines within a polygon.
So first I make a polygon. Now I need to fill this polygon with lines, where I can choose the spacing between the lines, and the ...
11
votes
2answers
296 views
Creating Thiessen (Voronoi) polygons using lines (rather than points) as the input features?
I have a set of line features inside a particular polygonal boundary. For each line, I'd like to generate a polygon inside which every possible point is closer to the given line than to any other line ...
5
votes
2answers
256 views
How to combine data from overlapping polygons?
Here's what I'm working with:
Shape file of the current 32 Congressional districts for all states
Shape file of the tract boundaries for Texas
A DBF format table of Hispanic counts and proportions ...
5
votes
2answers
106 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 ...
1
vote
3answers
201 views
How to auto fill or delete sliver polygons without losing precision?
I am developing some boundaries in which precision holds the key value.
Using ArcGIS 9.3 I am converting lines to polygons using the "feature to polygon" tool. The lines are accurate but I find ...
7
votes
2answers
901 views
How to check Topology in QGIS?
I have two Shapefiles with Polygons ( City and Forerst)
Is there a Plugin who is able check the topology (QGIS)? Like "Knots do not overlap" or something like that? I dont want that they overlap.
...
6
votes
3answers
646 views
Can Polygons be generalized to MultiPolygons in GeoDjango?
I set up a model with models.PolygonField in geodjango, using postgres as database. I try to import shp into postgres. The problem is, shp (compiled with QGIS) mixes polygon and multipolygon, hence it ...
4
votes
5answers
277 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 ...
1
vote
1answer
144 views
arcpy points in polygon check
I have a list of points and a list of polygons both in a separate shape files. I am trying to write a ArcPy script to loop through the points, and then the polygons respectively and tell me when a ...
3
votes
4answers
366 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 ...
0
votes
0answers
101 views
creating graphic polygon from extent in Arcgis JS API [closed]
I'm tryin to draw rectangle based on extent object. Could someone look trought my code and Tell me what am I doing wrong?
var polygon = {
"geometry" : {
"rings" : [[[extent.xmin, ...
2
votes
2answers
142 views
How to create a multipart polygon?
I have two polygons that consist of two separate polygons/lines in QGIS). How can I make this into a multipart polygon, which consists of 1 line in QGIS?
6
votes
3answers
568 views
How best to fix a non-noded intersection problem in PostGIS?
I'm using a PL/R function and PostGIS to generate voronoi polygons around a set of points. The function that I am using is defined here. When I use this function on a particular dataset I get the ...
9
votes
1answer
130 views
Compare spatial cluster/agglomeration patterns for polygon data
I have agricultural data in form of polygons which I would like to test for spatial clusterings/spatial agglomerations.
All in all I have about 40 variables which I can aggregate and standardize in ...
9
votes
3answers
2k views
How to merge two Polygons in OpenLayers?
I have two polygons.
polygon1 = new OpenLayers.Feature.Vector(new OpenLayers.Geometry.Polygon([linearRing1]))
polygon2 = new OpenLayers.Feature.Vector(new OpenLayers.Geometry.Polygon([linearRing2]))
...
