A geometric element defined by a pair of x,y coordinates.

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1answer
244 views

generate random world point geometries

I have a world map. I need random point geometry. So, how can I randomly generate point coordinates? Any programming language. Also, I am using SRID 4326. Any programming language.
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2answers
498 views

Joining Points and Polygons

I am new at using arcGIS 9.3.1 and am having trouble joining data. I have a shapefile of census tract polygons and a separate file of points that are crimes in Chicago in 2010. The crime points were ...
1
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1answer
215 views

random sampling from spatial points in R

Can anyone help me out on the best package to sample from a spatial point dataset? My dataset consists of a list of positions inside a region, and for each point I also have the name/number of the ...
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2answers
113 views

simplify point geometry

I have a great amount of points and I need to show them on map. I am using OpenLayers. Is it possible to simplify point geometry in order to speed up the process of rendering?
3
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1answer
1k views

Problems converting polygon to point [closed]

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
1answer
327 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 ...
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0answers
364 views

How to calculate average value within a polygon(in Qgis with Python)?

Now I have a point and polygon shapefile and I want to calculate the points' average value within each polygons How to do it with python? I tried to find out but google gives me a lot of raster ...
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0answers
101 views

Join .csv file and .shp of georeferenced points

I have georeferenced a map and saved a selection of some points on the map. These points are cities of departure and arrival and I want to join the .shp with a and excel .csv with the information of ...
3
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1answer
300 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 ...
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2answers
451 views

How can I disperse points within polygons using ArcGIS?

I have huge number of points. These points are within polygons. I want to disperse the points in the polygons randomly. I tried to use the disperse point extension in Arcview, but it was not useful ...
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0answers
181 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
345 views

Find projection of a point to a line

I have a segment defined by 2 LatLon points(A and B) and a third LatLon point (C). I need an alghorithm, formulae, or some code to find the projection point of C on the segment AB (call this point D) ...
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0answers
53 views

How to obtain and compare neighboring point attributes? (ArcInfo)

This question is kind of hard to explain in a short phrase, so this is what I'm talking about. I have access to an ArcInfo 10 license. I have a layer of point features that all have a "Team" ...
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2answers
123 views

Manually add a new point to PostGIS table [duplicate]

I did accidently delete a table row - or well, in fact a whole subway station. My attempt to solve the problem was this PostGIS function: ST_GeomFromText('POINT(coordinates)') But then PostgreSQL ...
2
votes
1answer
332 views

Correct coordinate systems, but trustworthy distance between points?

I have limited GIS experience with projections and I have some questions about trying to accurately display point data from two different sources in ArcGIS 10.1 in order to do a proximity analysis. ...
3
votes
1answer
1k views

How does Flow Mapper Plugin work?

I downloaded the Flowmapper plugin for Qgis and I can't seem to find any information on how it is supposed to work... Also the text seems to cut-off and not fully showing for the input fields so I'm ...
9
votes
1answer
255 views

Measuring distances between simultaneous points

I am working with GPS data and so I have UTM's with DATE/Time information. I have 2 groups of species (moose and wolves). I want to join the information from moose to wolves that match in time. So, ...
5
votes
3answers
244 views

GIS file format for space and time data?

I need some advice with GIS file format choice. Here is my problem: I have about 100 stations. At each station water temperature is measured daily for 1 year I want to load this data to QGIS and be ...
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2answers
768 views

Layers with same coordinates not lining up [QGIS]

I have a project where I have a few layers (State of Texas, cities, roads, etc.). They are all resaved and projected to NAD83 / UTM zone 14N EPSG: 26914. The project CRS is also NAD83 / UTM zone 14N ...
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2answers
235 views

Road network Analysis

I have a Road layer and Point features of some Bus stops from the same area.I want find the Road distance between the Bus stop.Please help me find it. I have QGIS,ArcGIS,and FME. Thanks, RKM
2
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1answer
4k views

Making POINT from longitude/latitude coordinates in existing table using PostGIS?

I would like to make a POINT using the longitude and latitude columns of an existing table. Here's a link to the documentation of ST_MakePoint. Here's my table: CREATE TABLE sysinst.bio ( oid ...
3
votes
2answers
128 views

Point file to raster

I have a point file of trees in my study area, which includes the attributes of each tree. Each tree also has a crown radius associated with it. I need to summarize the attributes of these points ...
7
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4answers
527 views

How to calculate the “depth” of a linestring using postgis

I have linestring features, which look like bent linestrings, hemicycles or convex or concave linestrings. In the moment I can select the distance between the startpoint and endpoint of each feature. ...
1
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1answer
122 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 ...
0
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0answers
178 views

Splitting a TAB file by attribute?

I have TAB file with LOADS of points. Each point as a unique ID and group assigned to it (ranging from 1-154). I'm wondering if there is an easy way to split this up into a TAB file for each group, ...
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2answers
1k views

Calculating angle between two points (according to reference point)?

I need to calculate the angles between two points on ArcGIS. I have ArcInfo License, too. I have 5 points on a diagram. One of them is my reference point. The other four creates angles between each ...
3
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2answers
558 views

Calculating the distance between points and multiple lines

I have a point shapefile of about 100 points and a polyline shapefile of about 200 lines and I am interested in finding the distance between every point and each individual polyline. My polyline ...
4
votes
3answers
595 views

How to join number of point features into attribute of nearest line segment

I have point shapefile with lot of attributes, that represent road accidents and line shapefile with highways. What i want is to join attribute into line shapefile with value, that represent number of ...
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0answers
64 views

Prediction a point position

I don't know if you could help me in this: I have 7 points (x coordinate is known and variable) (y coordinate is known and fixed) each point represents a position of the same object in a specific ...
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1answer
736 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
1k views

Calculate min distance between points in PostGIS

I have point layer in PostGIS database. Help please with query which add for each points in layer distance in attribute table between this point and another nearest point. Thanks! Update Calculate ...
5
votes
1answer
425 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 ...
2
votes
1answer
294 views

Postgis 1.4 - Obtain closest point of point over polylines layer (without st_ClosestPoint)

I´ve got a polylines layer (pipes) and a points layer (valves) and In Postgis 1.4 I would like to obtain the closest points but exactly on the closest polyline. In other words, i need to locate each ...
6
votes
2answers
1k views

QGIS or Postgis - How to split polylines with a point layer?

In QGIS, I would like to split the polylines in a layer loaded in the workspace with the points in another loaded layer. If a point intersects a polyline, this polyline should be transformed into two ...
1
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2answers
452 views

QGIS create layer with the points of the beginnings and ends of a polylines layer (without duplicate points)

In QGIS, i would like to create a new layer containing the beginning and end points of a polylines layer, but without the duplicate points that would result of adjacent polylines.
6
votes
3answers
653 views

Classifying point coordinates to countries or continents?

I have about 50 000 points (latitude and longitude), and I would like to find out in which country each of the points is located. It does not need to be super precise, though. (Or actually I only ...
7
votes
4answers
1k views

How to create different diameter circles round points?

I want to map a tree survey. I am thinking that I will plot positional points of the trees and then add other data like tree type etc. to the attribute table later. Is there a way I can have an ...
5
votes
1answer
239 views

QGis 1.8 fails to rotate point geometries with rule-based style

I have to do some visualizations in QGIS (1.8.0) and up to now I've been very happy with the new Dialog "Layer Properties -> Style", using the rotation-field to rotate Point-Geometries visualized by a ...
5
votes
1answer
154 views

How many GIS projects deal with just basic “putting markers on a map”?

Is there an academic paper or conference contribution, where someone estimated how many GIS projects actually deal with only a very basic usage of GIS data? Something equivalent to the infamous "80% ...
10
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2answers
2k views

Aggregating points to grid using R

I have a question with regard to spatial aggregation in R. What I am trying to do is aggregate a point dataset to a grid. I am unsure however how to do this as I have little experience with this sort ...
2
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0answers
42 views

Spatial indexing of a point pattern in R [duplicate]

I have a point pattern and a tessellation (grid) in R. Is there a way to spatially index each of my points? In other words, my tessellation grid has n quadrats, I would like to know for each of my ...
0
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3answers
355 views

Calculate 'Rectangle' Coordinates Given 2 Points and width [closed]

I want to create a rectangular polygon using two points as guides. So let's say a journey starts in Egypt and ends in London, my polygon should have 4 points: 10 miles further from London than Egypt ...
2
votes
1answer
1k views

Is it possible to place a point at a coordinate in QGIS?

Is it possible to place a point at a coordinate in qgis? I have a map, using irish grid reference and wish to place a point at an exact 6 digit coordinate. Is it possible to do it. Previous to this ...
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0answers
355 views

Creating points along lines? [duplicate]

Possible Duplicate: How to create a point along a line given distance How to create equidistant points in QGIS? I have some road survey data and each line has an individual value and ...
0
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0answers
56 views

How to format spreadsheet to input point data for later import to PostgreSQL

I want to create a spreadsheet to hold data from our cemetery. I will use the spreadsheet to get the data into a PostgreSQL database. What I dont know yet is the format that the point (positional) ...
11
votes
2answers
543 views

Moving points onto lines (~neighborhood)

I do have two vector layer, of which one is a point layer based on "events" by remote sensing and the second one is a line layer from local research. In my case these are earthquakes and tectonic ...
3
votes
1answer
208 views

How to determine error radius of given points

I am running QGIS 1.8.0 on a 64-bit Windows 7 platform. Given multiple points with different (but close) coordinates, how do I automatically create a new point that programmatically takes into ...
5
votes
2answers
168 views

How can I join a spreadsheet to a point layer?

I have a layer with point data for the grave positions in our cemetery. We are gathering data from each headstone. If I enter the data to a spreadsheet can I later associate the spreadsheet with the ...
7
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2answers
183 views

Algorithms for optimally locating points

I am trying to compare locations of where several thousand facilities have been actually built to where they would be optimally located to minimize travel times of the population (represented by ...
3
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0answers
257 views

How to Batch Change X, Y Coordinate Number in ArcGIS?

I have a huge number of points (100000 points). Some of these have the same x,y coordinates. For example, 50 points are same in x,y then 100 points are same in another x,y coordinates and so on. ...