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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0
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1answer
41 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 ...
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vote
3answers
44 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
61 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
43 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
43 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 ...
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0answers
26 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
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0answers
18 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
31 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
43 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
40 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
58 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
66 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 ...
0
votes
1answer
63 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
61 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
45 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 ...
0
votes
0answers
40 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 ...
1
vote
0answers
63 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
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0answers
30 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 ...
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0answers
16 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 ...
3
votes
1answer
45 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
57 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 ...
2
votes
1answer
35 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 ...
0
votes
1answer
101 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 ...
0
votes
1answer
42 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
35 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
84 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 ...
0
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0answers
28 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
27 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
35 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 ...
4
votes
3answers
199 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 ...
2
votes
1answer
52 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 ...
1
vote
4answers
132 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
0answers
37 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
140 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 ...
4
votes
0answers
72 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
63 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
68 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 ...
0
votes
1answer
51 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 ...
1
vote
1answer
63 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 ...
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 ...
1
vote
1answer
70 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 ...
2
votes
1answer
112 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 ...
2
votes
1answer
116 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
93 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
76 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
43 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
37 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?
4
votes
1answer
94 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 ...
1
vote
0answers
47 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 ...
3
votes
1answer
79 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 ...

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