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.
5
votes
2answers
87 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 ...
4
votes
3answers
67 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
(
{
...
0
votes
1answer
78 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 ...
0
votes
0answers
12 views
How to obtain a region polygon from Google Places Autocomplete
I am trying to use google places autocomplete to search for a place, get its polygon region from mapques/nominatim and render the result in google maps.
Here is where I am having difficulties:
...
5
votes
3answers
355 views
How do I use polygons to apply a unique value to all raster cells within those polygons?
In ArcGIS 9.3, I have a raster file that I would like to "mask" with polygons, giving a single value to all the raster cells that overlap the polygons. How can I do this? Here's a screen shot, where ...
5
votes
1answer
71 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. ...
4
votes
1answer
51 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 ...
0
votes
0answers
22 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 ...
2
votes
0answers
26 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 ...
-1
votes
0answers
30 views
polygonal join in ArcMap 10 (no need for attributes)
I have two large polygonal layers I am trying to join together. There are many polygons that are not overlapping and keeping the attributes between the two is not a priority. Any suggestions for ...
3
votes
1answer
659 views
Polygon to Raster Tool Problem
I am trying to create a raster data set from county level polygon data for the US. I have successfully created one raster from a dataset, but when attempting another, it does not work. I am ...
1
vote
1answer
38 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 ...
0
votes
1answer
45 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 ...
0
votes
1answer
61 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 ...
2
votes
1answer
140 views
Create a 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
...
1
vote
2answers
69 views
How to add a polygon from GeoJson 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);
}
...
0
votes
2answers
28 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 ...
3
votes
2answers
61 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 ...
2
votes
3answers
48 views
How to divide a polygon with another polygon
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 divide the polygon?
The polygons are stored in two different layers.
3
votes
1answer
70 views
digitizing (tolerence) error in line data
I have designed a large number of boundaries. For accuracy, I took lines in patches from different data sets and merged them into one. Now I want to turn them into polygons from lines. I every second ...
1
vote
1answer
32 views
How to get polygons from PostGIS table to PHP array best?
Currently I fetch polygons from a database table using ST_AsText(). The results are in text format, like the following.
POLYGON((84 104,212 48,321 122,243 179,275 238,131 240,84 104))
I am not ...
0
votes
2answers
54 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 ...
7
votes
1answer
208 views
How to rectify polygon-shapes in Quantum-GIS? [duplicate]
I have some polygon-shapes in qgis-1.7.0 and want to ensure that every polygon is a rectangle. See image below.
Is there any way I can do this in quantum-gis (or any other f/oss)? Or how can I ...
0
votes
2answers
55 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 ...
2
votes
2answers
59 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
4answers
164 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
56 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 ...
4
votes
0answers
84 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 ...
1
vote
3answers
66 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 ...
5
votes
0answers
77 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 ...
7
votes
4answers
8k views
Extract coordinates of polygon vertices in ArcMap 10?
I've got about a dozen polygons in a feature class loaded in ArcMap 10, all in geographic WGS 1984.
How do I easily obtain the coordinates associated with each vertex of each polygon in that feature ...
1
vote
0answers
47 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
0answers
49 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
0answers
31 views
QGIS GPS live tracking adding polygon vertices
Maybe I'm missing something or maybe it is a bug? I'm trying to add polygons using the GPS information console. The only button available to record data is "add polygon", but if you click on it, you ...
3
votes
1answer
373 views
How do you convert raster to polygon while avoiding small polygons
I intend to convert a raster to several polygons, but I want to ignore too small polygons, and just keep larger polygon. How can I do that?
Thanks in advance!
3
votes
1answer
37 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 ...
2
votes
1answer
47 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
46 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 ...
2
votes
0answers
70 views
Problems converting polygon to point
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 ...
2
votes
1answer
74 views
ArcGIS - merge polygons and get combined area
I cannot for the love of god figure out how to 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 ...
2
votes
0answers
65 views
Cannot reselect polygon after modify
I've got various vector layers on a OL map.
On one layer I have a few draw controls. If I draw a polygon I can select it (the whole pop-up thing works). This also works for all the other features.
...
1
vote
1answer
89 views
Why is ArcMap 10.0 editor deleting some added vertices and simplifying polygon?
I am using ArcMap 10.0. I am trying to edit (and add) vertices in a polygon.
I start editing, (using "Edit Vertices" tool), and add many vertices in the polygon.
Then when I am done, I save the ...
2
votes
3answers
69 views
How to minimize the number of points 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
52 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 ...
2
votes
3answers
127 views
Best program for crowd-sourced polygons on Gmaps
Looking for a way to crowd-source polygon creation on GMaps (in a wiki environment) that doesn't involved ESRI's expensive server software.
Requirements:
- a bunch of different wiki pages can be ...
1
vote
0answers
69 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
49 views
Fill polygon with colour depending on the value in MS SQL Server table
I'm using QGIS 1.8. Windows 7. I have a table in MS SQL Server 2008 R2 database with two fields: id and density(int). There are several polygons in QGIS. How can I set color of polygion depending on ...
3
votes
0answers
74 views
Why doesn't Polygonizer copy the line ids to my polygonized shapefile?
I am trying to convert a line shapefile into a polygon shapefile using Polygonizer plugin, and when my new polygons are created all the cells in my id field are "Null", although I have clicked "copy ...
0
votes
0answers
41 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 ...
