Tagged Questions

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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2
votes
0answers
74 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 ...
1
vote
0answers
51 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 ...
14
votes
2answers
752 views

Is it possible to gray out a Google Maps map except for some area?

What i am looking for is a way to emphasize a certain area on a Google Maps map by graying out the rest of the world. I heard about some solution of using 2 polygons of which 1 is visible and the ...
1
vote
1answer
333 views

Calculate polygon area inside extent

We're using ArcMap 10.0 sp5, creating a tool in c# using the ArcObjects sdk. Is there a built in function or simple set of steps that calculates the area of each feature of a polygon layer within a ...
0
votes
0answers
26 views

polygon/raster intersection artifacts

I'm intesecting a polygon with a raster using PostGIS > 2.0. The outer boundary of the polygon is formed by the convex hull of polygons (building outlines plus safety margin) and the inner rings are ...
8
votes
1answer
94 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 ...
1
vote
2answers
98 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 ...
5
votes
2answers
104 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 ...
5
votes
3answers
89 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
13 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
366 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
74 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
55 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 ...
1
vote
0answers
30 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
28 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
32 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
674 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
39 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
47 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
62 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
142 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
76 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
29 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
63 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
50 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
34 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
56 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
209 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
62 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
169 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
61 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
68 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
80 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 ...
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
380 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
49 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
1answer
78 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
66 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
70 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
53 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
128 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 ...

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