A geometric element defined by a pair of x,y coordinates.
11
votes
5answers
9k views
Get list of coordinates for points in a layer?
I've got a layer in QGIS that is comprised of points. Its attribute table doesn't have the corresponding x y coordinates for each point. Is there a way for me to extract a list of coordinates for ...
13
votes
4answers
787 views
algorithm to place maximum number of points within constrained area at a minimum spacing
I have a polygon layer that describes a constraint; I wish to add points within this area. I want to add as many points as possible, but they must have a minimum spacing between them. Is it possible ...
11
votes
8answers
4k views
How can I convert an excel file with x, y columns to a shapefile?
How can I convert an excel file with x, y columns to a point shapefile?
There are some somewhat optional requirements in addition to the correct creation of a shapefile:
Column types (as per ...
19
votes
6answers
2k views
How to compare two spatial point patterns?
If I have two point pattern distributions within the same geographic region, how would I go about visually and quantitatively comparing those two distributions?
Also assume I have many points within ...
10
votes
3answers
2k views
How to join attributes from nearest point in QGIS?
I have two layers with points, call them A and B, each with different attributes.
For each point in A I want to join all the attributes from the nearest point in B.
Ideally this would also include ...
3
votes
1answer
925 views
Calculating distance to points in QGIS
Is there a way of calculating the distance to the nearest points in QGIS? In ArcGIS there is a function called Euclidean Distance, which can take an input vector or raster, and generate a raster of ...
3
votes
2answers
2k views
How to use Distance Matrix tool in QGIS?
I have a point data set. Now there are cluster of points based on a field. So I take out one such cluster which has points with same field.I want to find distance between all the points in cluster and ...
4
votes
6answers
5k views
Points to Polygon
I've millions of points collected for lithology layer. They have used a coding for different types of rocks. I need to create a polygon around the extent of similar points. What is the easiest way to ...
6
votes
1answer
192 views
How to draw shapes with highest possible decimal accuracy
I am trying to read input of lat and long to draw the shape based on condition.The input is standard array of lat and long with 15 decimal accuracy. I am realizing - I am loosing some decimal accuracy ...
5
votes
3answers
226 views
Is there a tool to add “noise” to overlapping X, Y coordinates so they are no longer in the EXACT same place?
I have a series of points representing animal observations. Many of them overlap, having the exact same coordinates, and this is causing me trouble when I want to run some analytical tools which ...
4
votes
4answers
472 views
How to represent several points with same coordinates on map?
I'm working on Arcgis 10.
I have a point shapefile representing events with several points having coinciding coordinates (They have the same coordinates). For representing them in a dynamic way, I ...
3
votes
3answers
196 views
How to perform a join on simultaneous spatial and attribute criteria in ArcGIS?
I have two point layers and want to perform a spatial join on nearest distance.
Normally it is easy with ArcMap. But now I have a restricting condition on the spatial join. The restriction only ...
3
votes
1answer
1k views
QGIS calculate distance of point along a line
I have a polyline (movement path) and points recorded along the line. I would like to calculate for each point the distance along the line in Quantum GIS. I hope for a result which will add a new ...
14
votes
2answers
2k views
How can I find a point inside a polygon in PostGIS?
How can I find a point that is guaranteed to be within a given polygon in PostGIS?
I am aware of the ST_Centroid function. However, the centroid is not always within a polygon, see below:
...
10
votes
2answers
199 views
How to identify and simplify point clusters with regard to time in PostGIS?
I just started to work with spatial databases and I want to write a SQL(PostGIS) query for automatic generalizing of raw GPS-tracks (with fixed tracking frequency). The first thing I am wokring on is ...
8
votes
1answer
329 views
How much sense does it make to average (lat,lon) samples in order to increase 2D accuracy of a GPS location?
Several GPS applications, like this one, or this one, acquire multiple (lat,lon) samples of a given location, assuming that the GPS unit is not moving, and then take an average of the samples in order ...
7
votes
4answers
8k views
How to find the distance of a point along a polyline?
We need to find the distance of a series of point along a given polyline.
We have a polyline dataset repsenting rivers in a catchment, broken up into river reaches (FID 1 through 35 for example).
We ...
5
votes
2answers
1k views
Creating evenly distributed points within an irregular boundary
I need to create an evenly distributed series of points within a series of oddly shapped polygons (formerly squares, but now squares with donut holes).
The way I have solved this problem so far is to ...
9
votes
3answers
2k views
What is quickest way to select polygon by point in ArcGIS 10 using ArcPy?
I keep thinking that I must be missing something, but there does not seem to be a tool in ArcGIS 10 to select features (in particular polygons) from a layer at a point (X,Y) location via ArcPy. The ...
7
votes
2answers
257 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 ...
6
votes
2answers
173 views
How to add vertices to existing linestrings?
If I have
Linestring(1 2, 1 5, 1 9)
and a
Point(1 3)
Is there any function that can merge linestring and point preserving the order
so output would be:
Linestring(1 2, 1 3, 1 5, 1 9)
6
votes
4answers
582 views
How to filter wrong GPS points?
I have a database of GPS points. There aren't any tracks, only points. I need to calculate some value for every 100 meters, but sometimes GPS gave a wrong coordinates that lies far from real GPS ...
5
votes
9answers
6k views
ArcGIS: Create a line layer from a point layer and csv data file
UPDATED DECEMBER 20
I have a Regular point layer and a csv file that has the same ids as the point layer. The csv file is organized as
ID From To Weight
-- ---- -- ------
01 ...
4
votes
1answer
2k views
Arcgis 10: Point layer, polygon line layer, draw points to the nearest polygon point or other nearest line?
I have been using arcGIS for a while now but I often get frustrated with it :(
I have version 10.0 arcGIS and I'm have two layers
1) Point data (building locations)
2) a polygon shape file (outline ...
3
votes
1answer
729 views
convert list of points to line or polygon
I have a list of Points in a PostGIS table. The rows can be grouped by a date
something like:
myTable
id INT
date DATE
lat NUMBER
lng NUMBER
geom GEOMETRY(POINT)
now I need a table where all ...
6
votes
7answers
2k views
Extract raster values at points
How can I extract values from a raster by points. I prefer not in Arcgis. I prefer in Qgis or Mapwindow or other open source gis.
5
votes
3answers
2k views
Is there a way to label points in a regular interval in ArcGIS 10? [SOLVED]
Estou trabalhando com linhas em estradas representadas por uma grande grande quantidade de pontos em sequencia.
Uma vez que colocar o nome de todos os pontos tornaria a identificação impossível, ...
4
votes
4answers
103 views
How do I fill in serial letters (AA, AB,AC…,BA,BB,BC…ZZ) to a shape?
(I am using ArcGIS software, ArcMap...)
MY PROBLEM
I have a shape file containing points. The shape file contains 3 columns named FID, Shape* and Label. In the column I want to fill in AA, AB, ...
4
votes
2answers
391 views
Does anyone know a function to determine if a Point lies on a polyline?
ArcEngine 10 .Net 4 c#
Hi I'm currently allowing user to select a point on a polyline and creating a point on the line. I am using snapping tool.
I just want to make sure that when the user clicks ...
4
votes
5answers
13k views
How to connect points with a polyline in ArcMap 10?
I have a layer containing a few hundred points representing a survey track. The points are laid out in chronological order in the corresponding attribute table.
How can I have ArcMap 10 automatically ...
2
votes
1answer
1k views
How to add points to a point vector layer - QGIS
I have a point layer with multiple data points in QGIS, but I want to add some extra data points to it and adjust some info that we missed because the ground was wet and we needed to go around it. I ...
1
vote
1answer
27 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.
1
vote
2answers
224 views
OpenLayers: how to save added point in server side
I'm new in OpenLayers.
I have simple application, which use a picture as map,
on this picture users can add, move, or delte point, and then save.
I have implemented adding, moving, deleting ...
1
vote
2answers
1k views
Hyperlink relative paths to files in points layer in QGIS?
I would like to add hyperlinks to each point in a points layer in QGIS 1.7.0 running on Mac OS X 10.6.7, but I have several requirements:
(1) Each hyperlink has to be a relative path to the linked ...
0
votes
2answers
47 views
Creating a 3D line feature based on 3D point features
In ArcGIS, is it possible to create a 3D line feature by drawing a line that connects 3D point features?
0
votes
2answers
59 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 ...
-1
votes
1answer
55 views
QGIS and Python - create line with multiple points in postgis
How can I create a line, with Python functions, with many points that are records in Postgis?
Thank you
