A common GIS operation. Used to determine whether a point lies within a polygon's bounds.

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7
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3answers
3k views

Overlay a spatial polygon with a grid and check in which grid element specific coordinates are located

How can one use R to split a shape file in 200 meter squares/sub-polygons, plot this grid (incl. ID numbers for each square) over the original map below, and evaluate in which square specific ...
2
votes
1answer
60 views

Identify geographic location to points

I am quite new in QGIS and I really need your help. I have a map of Kenya divided into 68 districts and I have coordinates of 30.000 schools. The points have one variable besides the latitude and ...
3
votes
1answer
68 views

Qgis creating point within complex shapes (with holes) [duplicate]

I'm looking for a tool to create a point in every polygon, that will be placed in the polygon. these are complex shapes with holes. the point must not put in those holes! the "plugin RealCentroid" ...
4
votes
1answer
2k views

Shapely unable to tell if polygon contains point

For an application I want to determine under which constituency a given coordinate falls. After looking at the various options, I decided upon shapely and fiona as the easiest way to implement this. ...
0
votes
1answer
32 views

Determine when a route enters and leaves a polygon

I have all of the segments of a route from White Horse, YK to Miami, FL. Now I want to determine how many miles I travel in each State / Province. I have Polygons for each State and have been able ...
2
votes
2answers
426 views

How to find the row that has a shape file containing a lat long point in my PostGIS geometry column

I am fairly new to PostGis and I'm trying to return a row in my table that has the shape file containing a lat long point I pass in via st_contains. Below is a query I wrote myself that brings back 0 ...
1
vote
1answer
90 views

Use field calculator in QGIS so get number of points in polygone and store it in attribute table

I have to layers, one point one polygon (with 6 areas) stored as shapefiles. Now I want to count the number of points in each area and write it into the attribute table of the polygons. A column ...
1
vote
1answer
2k views

How to find points inside each polygon in Mysql?

I have points table (with latitude and longitude columns) and polygons table with geometry stored in Mysql. I want to get points inside one polygon, for example in polygon which has column ...
2
votes
3answers
113 views

How to write FIDs of points within each polygon to polygon field?

I have two feature classes one with points one with polygons (in ArcGis 10.2). Now, I want to write into a String Field of the polygon layer a list of all the Point-FIDs that are within each polygon ...
1
vote
3answers
630 views

How to create random point in according polygon for each dataset entry in a list (with R)

I have an area divided into polygons, and a dataset of observations which has a common field with the polygon layer. I now would like to generate a random point for each dataset entry within the ...
1
vote
2answers
875 views

Python - GDAL : Polygon to point shape file

I want to read all the points in a polygon shape-file and use their coordinates to make a new point shape file. then find the min and max of the X coordinates. So here is the code I wrote for the ...
2
votes
1answer
233 views

Fast zipcode detection from latitude/longitude

I need a way to get the zipcode of a lat/long pair fast (<10 ms), and at a high rate (thousands of qps) I've loaded a shapefile from the US Census Bureau into a mysql database with spatial ...
0
votes
2answers
581 views

Intersection between points and polygons in QGis

I have the following problem. I have a shapefile of points and a shapefile of polygons. I want to know WHAT points (not how many) fall inside EACH of the polygons of my multipolygon shp. I thought ...
1
vote
0answers
155 views

Divide polygon based on points for even distribution

If I have a point layer, how can I create a polygon that includes all of the points and divide that polygon into n sections in which each section contains an equal number of points? Preferably in ...
2
votes
0answers
57 views

What is the MS SQL Spatial syntax for counting points within polygons? [duplicate]

All, What I'm trying to do is this: Count points within polygons There are thousands of points and maybe 2 dozen polygons Get a list back of the 2 dozen polygons by name and the count of points ...
0
votes
1answer
2k views

How to extract polygon location data (County) to a point shapefile (only has DMS)

I have imported an excel spreadsheet to my map and the points have fallen into certain locations. How do I add the location of the polygon that the point has landed in, to the attributes table of the ...
1
vote
0answers
166 views

Can I get a list of points in a polygon using Quadtrees?

I'm storing vertices in a PR (or PM if needed) quadtree and would like to be able to: Find out if a given polygon contains at least one point Optionally: Get a list of all the points within a ...
1
vote
1answer
99 views

Finding point in polygon

I want to calculate a point in a polygon, if the centriod falls inside the polygon it is what I want, but if it doesn't I would like it to be a visual center point. Essentially I want to do the ...
1
vote
1answer
171 views

Add buffer only on one specific side of polygons

I have a shapefile with multipart geometry (multipolygons), namely communities (blue on the picture below). There are also lakes (white), but for these I don't have a geometry, they're just "empty". ...
0
votes
0answers
318 views

Point in polygon analysis fails with “TypeError: arguments did not match any overloaded call”

I am using QGIS 1.8 on Windows 7 I want to perform a point in polygon analysis using the Vector > Analysis Tools menu. My point layer is the result of a SpatiaLite query which returns 10'000 points. ...
2
votes
2answers
1k views

Checking if Lng and Lat fall inside polygons from ESRI Shape file

I have two input files. First: CSV file with a list of points each defined with Lng, Lat, Name Second: ESRI Shape file defining a number of polygons I would like to determine for each point I have ...
3
votes
2answers
127 views

How to query for a specific point, within a specific polygon?

I have a shapefile points layer, with each point representing either Marginal, suboptimal, or optimal conditions. I want to find only the marginal points within a specific polygon from my catchments ...
2
votes
0answers
153 views

ray casting on earth's surface

Is it safe to use ray casting algorithm to check if a coordinate is inside a polygon specified as coordinates? Purpose of my question is because the longitudes are not parallel in a Cartesian sense, ...
2
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0answers
185 views

How can I improve my Ray casting algorithm?

I have been using the following function below which have been working well to decide if a point in the polygon but once I have many points which is building the polygon say over few thousand it seems ...
2
votes
0answers
144 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" ...
3
votes
2answers
2k views

Count Points in Polygon with Postgis

I've got a simple problem: I want to count the number of points within a set of polygons. I have a SQL already but it only gives back the gid of the polygone that actually contains points. My ...
5
votes
2answers
2k views

Total of attribute field of point layer per polygon layer

I have a polygon shapefile of many lakes, I also have a point shapefile of locations on those lakes where fish were caught. The point shapefile contains the attributes: Fisherman_iD, Fish_Caught, ...
4
votes
1answer
654 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
2answers
590 views

Function for Selecting Points in a Polygon

I've been banging on this for a few hours, but since I'm relatively new to PostgreSQL and PostGIS, I can't find the solution. I'm trying to create a stored procedure (function) which will return all ...
0
votes
1answer
58 views

Display county for random points

I have a county level shape file for South Carolina. I generated random points using Vector->Research Tools-> Random Points. The Attribute tables for the random points layer has only the ID included. ...
2
votes
1answer
354 views

Tearing in ggmap (R) after using spTransform and random point generation using splancs

I am using R and the package ggmap to try and generate some random points within the city limits of Chapel Hill, NC. I have downloaded the shapefile for the town of Chapel Hill from the Orange County ...
6
votes
1answer
484 views

How to determine optimal windmill placement to maximize production?

How can I add automatically the maximum number of points (dots) with 6m diameter and 100m distance each point from other into an area. The dots will present the windmill base (6m) and I want the ...
4
votes
1answer
2k views

STIntersects - Update field to give me count of points in polygon

I have a points layer (dbo.ptLayer) Around 1M points Spatial Geometry Type (dbo.ptLayer.geom) No spatial index just yet, but will create one once data gathering complete. I have a polygon layer ...
1
vote
0answers
248 views

How to update polygon field with point count for multiple rows? (Temporal point-in-polygon)

I have a shapefile with several regions. It contains basic info like ID, Code, Name1, Name2, etc. It is overlaid with a shapefile of points (nearly 200k). Each point represents an event with a type ...
6
votes
3answers
6k views

Check if lat/long point is within a set of polygons using google maps

I know how to do the above using Esri (Query task on shapefile), but can this also be done using Google Maps? Do I have to query each polygon or is there one method to query a set of polygons?
7
votes
2answers
325 views

Update database row with points that fall within polygons

All, I have a PostGIS/Postgresql DB that has two tables in it. One with point geometries and the other that represents country boundaries as polygons. I would like to add the country name that each ...
5
votes
1answer
187 views

Which polygons surround this point? A practical case of political geography

I'm starting a project from scratch but am budget constrained. In plain language I've got no money. What I want is to provide an address and return what governments have jurisdiction there. The ...
0
votes
1answer
170 views

How to add a label of a point to a polygon

i have several polygons with in each polygon a point with a label (number). I want to add the label in the polygon to the attribute-table of the polygon it belongs to.
6
votes
2answers
5k views

Create a polygon layer from point data

I'm currently using QGIS 1.8.0 I would like to create a polygon layer from a point dataset, where the size of the polygons relates to the resolution of the grid reference. The ultimate aim would be ...
2
votes
2answers
2k views

Is it possible to extract Coordinates of Polygon Centroid in QGIS?

I have created polygon centroids using one of the "Geometry Tools" but I would like to extract the actual coordinates into Excel for further work. Is this possible?
4
votes
1answer
2k views

How do I add polygons to an existing attribute table where the data is stored as points? ArcGis 10

I have a shape file of golf courses saved as points, I would like to digitise the boundaries and add the polygons to the existing attribute table. I have opened editor and clicked on the point data ...
3
votes
2answers
213 views

Points in polygon by months

I have two tables: points(gid,id,datum,x,y,geom) and hexa_grid(gid,geom). I must create new table hexa_grid_pip (gid,2008_01,2008_02 ... 2011_12, geom) In column 2008_01 ... 2011_12 must be number ...
1
vote
2answers
322 views

How to implement a spatial query on polygon data for a specific point?

I have vector data fed into a database which returns a report at province level upon querying. This is implemented in a web tool. I want to add an extra functionality at point level, where I can ...
5
votes
3answers
1k views

How to identify feature vertices that are part of a donut hole in ArcGIS 10?

I´m exporting the coordinates of polygon vertices to a CSV-File using the "Feature Vertices to Points" and then the "Export feature attributes to ASCII" tools. Some of these polygons have holes ...
2
votes
1answer
763 views

How to find most frequent values?

Entry layers: polygons - no attributes (columns/values), points - needed attributes (columns/values) How to get this result?: polygon layer with attribute (column/value) of most often (most frequent ...
1
vote
3answers
4k views

How to check if a point is near or inside polygon?

I am trying to find a simple library which can do point in polygon. Earlier i did hit Java Spatial Index library ...could not figure out. Tried openmap..looked simple didn't work. I am totally new ...
4
votes
3answers
8k views

Solving the Point in Polygon Problem Using Google Maps and Fusion Tables

The Point-In-Polygon problem is fairly well documented on this forum. My question is if there is a way to use Google's free tools, i.e. Google Maps, Fusion Tables, and possibly Google Refine, to solve ...
2
votes
2answers
506 views

Map Coordinates to Neighborhoods from MySQL Table

I have a MySQL database with a set of coordinates and a shape file (Zillow Neighborhood Database for Chicago) containing the boundaries for each neighborhood which I have converted to a spatial ...
4
votes
1answer
720 views

Calculation of average point distances from one another within a polygon grid

I am working with processed LiDAR data of forested areas in ArcMap 10, with various area based statistics extracted for each 30x30m polygon grid-cell in a shapefile. There are approximately 20,000 of ...
2
votes
3answers
1k views

Accessing coordinates of polygon

I have designed a polygon in a web page and the coordinates are stored in the database of the type polygon. However when I check the database, I find GEOMETRY - 120B under polygon field. What does ...