Questions tagged [nearest-neighbor]
A technique for resampling raster data in which the value of each cell in an output raster is calculated using the value of the nearest cell in an input raster.
159
questions
2
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38 views
Nearest neighbour analysis from existing Excel sheet
I learnt the Nearest Neighbor Analysis from QGIS Tutorials and Tips. The result of this analysis, see image below
I know that after running the distance to nearest hub analysis, it produces hub lines ...
0
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0answers
13 views
Calculating number of points within certain radius for multi-type point patterns using R [closed]
I have two sets of points, A, and B, and they are defined in the same region.
For each point of A, I want to calculate how many points of type A and B are within the circle, respectively(radius = r)
...
1
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1answer
24 views
ST_ClosestPoint() moves all points to one line instead of closest line
I have a line network and I've created evenly-spaced points along those lines. The problem is that the points are not exactly on the line so subsequent overlay operations will not work as expected. I'...
7
votes
1answer
173 views
Rockfall analysis (Nearest neighbor downhill) in QGIS
I am working on a rockfall guide for QGIS and I'm currently stuck on one of the stages.
I currently at a point in the guide where I have two point layers one "rockfall release point"-layer and "...
1
vote
1answer
22 views
Nearest Neighbor Two Point Tables Return Line Geometry
I am looking to find the nearest neighbor between two point tables in PostGIS and return the ids of both along with the line geometry. I have been able to determine the distance for the nearest ...
1
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1answer
28 views
Spatial 1 to 1 join by proximity in sf and R?
I'm trying to join a Simple Feature of POINT geometry type to another Simple Feature of POLYGON geometry type using st_join and nngeo::st_nn as the person asking this other question also did. The ...
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20 views
Nearest Neighbour along a route instead of geographical displacement
Say that I have three layers as follows for a certain region:
Line Layer representing roads
Point Layer representing hotels
Point Layer representing train stations
Using QGIS is there a way in which ...
2
votes
1answer
63 views
ST_Distance does not give nearest node
I am trying to find the nearest point on the road network closest to a given point. I imported the road network into PostGIS from QGIS and am using the SQL window in QGIS DB Manager to query the road ...
1
vote
1answer
44 views
Distinct st_shortestline
I have 61 pts and numerous rds. I would like to find the shortest distance to the nearest road using st_shortestline. I need 61 unique line segments, one for each point to its nearest road. Instead I ...
3
votes
1answer
111 views
Calculating nearest neighbor within each polygon using QGIS?
I have 3 layers:
world map divided into countries;
layer of points representing cities;
layer of points representing conflict events (e.g. firefight).
My goal: For each city, calculate the nearest ...
3
votes
2answers
84 views
Calculating distance between multiple lines of points in QGIS?
I'm looking to calculate a distance from a sensor reading to that of the nearest sensor reading on a different sensor line, all held within the same points file. Ideally using QGIS.
The image below ...
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0answers
31 views
NearestNeighbor producing bad quality tiles
I have been using Bicubic interpolation to render some basemaps because this produced good results. This is what I get when using Bicubic:
However, when using Nearest Neighbor interpolation, a white ...
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33 views
Finding nearest 10 observations that occurred 2 years before original observation using ArcGIS Pro ModelBuilder?
I have a point sample of house sales (~42k points over 9 year period) with a date field(integer), and for each point I want to find the 10 nearest houses within a year of sale and also which were sold ...
1
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1answer
23 views
How to get Memory layer dispalyed in Vector Panel List using Pyqgis?
I have two point layer in my Project Centroid.shp and Nodes.shp.I have used Distance Matrix to find nearest Nodes point from Centroid Point. I have saved the output in FinalDistance.csv. The ...
1
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1answer
65 views
Error creating DEM with Nearest Neighbour tool in QGIS?
I have an issue when I am creating a DEM with the tool natural neighbour on QGIS.
When I extract my data directly on Qgis I have no issue creating a DEM. My points are coming from different sources ...
2
votes
1answer
33 views
Neighborhood Analysis with ArcGIS Spatial Analyst to Calculate Percentage
I have a raster file where the cells (1 meter) are classified as 1 (forest) and 0 (non-forest). I would like to create another raster (1 meter) where each cell is given the percentage of cells within ...
2
votes
2answers
329 views
Combining st_join with st_nn to include all points within, as well as within a given distance of a polygon
This is a follow up to my earlier question (Spatial join in R - Adding points to polygons with multiple corresponding points).
I have successfully joined a spatial points file to a polygon file in R ...
0
votes
1answer
90 views
Nearest Neighbor - return object ID in R
I have a csv file that contains the GPS coordinates of about 100 villages and their unique ID. I have an other csv file with the GPS coordinates of some potential destinations and their unique ID.
I ...
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0answers
43 views
PostGIS - Nearest Neighbour Join to sum values
I have a table of polygons T1 and a second table of points P1
Each point has a value
I want to sum the values of P1 for each T1, with P1 being the closest set of points to T1
At the moment the only ...
0
votes
1answer
147 views
Find the closest Point from a Point which contains the same attribute
I am trying to create python code to iterate through points on 1 layer and find the closest point on another layer (Road Chainages) based on attribute values. I need to limit the search to < 20m ...
0
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1answer
27 views
Seeking package/function in R that can help tag GPS coordinates of fauna sightings to nearest sampling point?
I have 1 dataset of animals sighted walking a survey, and I would like to tag them to the respective sampling points along a transect.
Any idea what function/package in R can do that? Maybe ...
2
votes
1answer
504 views
Nearest Neighbor Analysis Results
I'm fairly new and entirely self-taught in using QGIS 3.4. I'm looking at turtle nest sites and trying to run a nearest neighbor analysis to analyze their distribution and establish whether or not ...
0
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1answer
381 views
Spatial join attributes based on closest point in PostGIS
I have two point tables from which I want to extract a value from one table to the other, based on the nearest distance of those two points.
t1 t2
id | value id
1 | 100 1
...
2
votes
1answer
47 views
How to find the closest stop point PostGIS
I have Point geometries created from lat,lon
I loaded all the 10,000 stops in a certain city using gtfs
i would like to query my db to find the closest stop reference to my point.
the staypoint ...
3
votes
1answer
216 views
PostGIS -> LineString + PointZ = LineStringZ
DATA
I have 2 tables in PostGIS:
linestable with MultiLineString geom
surveypointtable with Point + elevation attribute
GOAL
The goal is to rebuild the lines as 3D replacing line's vertices with ...
-1
votes
1answer
154 views
SRTM/DEM 1m resolution (batymetri) to point [closed]
I have bathymetry data (1 huge data) =
SRTM/DEM/FGDBRaster (0,9818m resolution pixel, floating, 32 bit, 45 GB size)
and an alternative data (split into small pieces data) =
same data but with 1m ...
1
vote
1answer
270 views
A line between point to nearest neighbour point using QGIS
I have a layer of points in QGIS which represent electric poles
How do I create a polyline layer that would have lines running between the poles so it can represent the the electric cables that ...
2
votes
1answer
322 views
Efficient way to find nearest feature between huge postgres tables
I have two tables (g1 and g2), both with around two million features. I need to know for each feature in g1, which is the closest feature from g2, with a condition. Since they are both so huge, I also ...
1
vote
2answers
228 views
Excluding point from Nearest neighbor search once it's been matched using R?
I have two lists of addresses, List 1 and List 2. I want to find the nearest neighbors of the list--but without assigning more than one point to any point. So say point 1A is the nearest neighbor of ...
4
votes
2answers
168 views
Query takes very long time
I'm a newbie to POSTGIS and I wonder if someone could help me out.
I have loaded all postal codes with their geographical coordinates (geography) and created an index on this coordinate.
When I run ...
3
votes
1answer
149 views
Get closest road-segment to segmentized LineString points
So I have a table that stores a bunch of traffic counts for various road segments across the country. I'm regularly getting real-time location data from vehicles that are moving around a given region ...
0
votes
1answer
108 views
Query to return closest LineString given a Point [duplicate]
I have a road lines data in a table with field
roads(id SERIAL ,the_line geometry(LineString,4326))
suppose an accident occurs in a middle or at any location in that waterline i want to stop the ...
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vote
0answers
161 views
Interpolation in QGIS shows wrong output result [closed]
I have done interpolation (IDW and Nearest Neighbour) in QGIS. But interestingly the output shows the wrong result. The area where I have a huge number of points results in a lower Z value (it is ...
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vote
0answers
132 views
Nearest Neighbour Analysis Or NN join
I have two Layer in my Project
1) Voronoi Layer which is constructed on point Layer
2) Building Layers which is represented as Polygon.
The goal is to find the nearest node for every polygon (...
1
vote
1answer
72 views
No module named 'mmqgis'
I have two layers in my Project
1)Points Layers
2) Polygon Layer
I need to apply nearest neighbour Analysis between point and Polygon, but i am unable to get .
I tried the below code.I am using ...
1
vote
1answer
101 views
Constructing Voronoi Polgon and Applying Nearest neigbour in it
I am learning QGIS 3.XX and currently working on Voronoi Polygons.
I have three layers
Point layer
Building Layer
Population CSV file.
These points layer are basically water tanks and building ...
2
votes
0answers
220 views
Geo-hash finding nearest neighbour with massively variable distance to actual nearest neighbour
I have a series of points in lat-long space, ranging from having their nearest neighbour very close to 1000s of km away. Say I do a geo-hash of these to a high precision, my search of nearest ...
0
votes
1answer
176 views
Optimizing a nearest neighbor search in PostGIS for a large dataset
The below code is working well for smaller datasets, however I want to use this with a 30 GB table. Every time I run it using the larger table I run out of SSD space, the table gets to 127 GB in size!
...
2
votes
2answers
505 views
Nearest Neighbor
We've got a table of approximately 300,000 points and would like to find the nearest neighbor (within 10km) to each point in the same table. The most efficient query we've found so far is below, but ...
2
votes
0answers
204 views
Find the nearest neighbour for points in one layer to points in another, then measure the distance
USING QGIS 2.18.19 with python console (planning to upgrade to the newest QGIS after this piece of programming)
I am struggling with finding the correct pyQGIS coding for this.
I have a shapefile ...
1
vote
1answer
149 views
For each row of GPS coordinates, get value from nearest road to coordinates and copy to said row using PostGIS? [closed]
I have two tables in my database; one contains a set of GPS coordinates of a car which have been converted to geom, and another containing Open Street Map road data, including the speed limit for most ...
1
vote
1answer
292 views
Nearest point on line from a point in PostGIS and its attribute value
Consider the following image;
I have points (shown in blue circles) stored in my database with their geometry and an attribute value. Additionally, I have another table with User Points (yellow ...
1
vote
1answer
54 views
Get barrier edge id
I have a table of POINTs that represent barriers. I would like to be able to find the closest edge id on the edge graph so that I can have the routing algorithm ignore that edge (thus route around it)....
2
votes
1answer
153 views
QGIS 3.0.2 NNJoin doesn't complete. Crashes when close status bar
I have run a large spatial point to polygon join of 2 million points to 657 polygons. I used NNJoin so that the closest polygon will be assigned to a point if the point does not lie within one.
The ...
3
votes
2answers
156 views
Nearest Neighbor search in PostGIS using cases
I am using the following PostGIS nearest neighbor query to determine how close a point is to an area (polygon) that has been flooded and it's working well:
SELECT
ST_AsText(ST_SetSRID(...
3
votes
2answers
831 views
How to UPDATE with LATERAL Nearest-Neighbour query?
Say I have table gps like:
CREATE TABLE gps(
gps_id serial primary key,
measured_timestamp timestamp,
geom Geometry(Point,4326),
stop_id int --Null
);
And I have a table of stops like:
...
3
votes
1answer
426 views
Merging overlapping polygons with original polygons in QGIS
I have a large vector shapefile dataset containing polygons, many of which overlap.
I want to assign each overlapping section to one of the original overlapping polygons. E.g. if polygon A overlaps ...
1
vote
2answers
165 views
ST_ClosestPoint usage in QGIS 3.0
I try to use ST_ClosestPoint function to find the closest point to find the MultiLineString layer. My line layer (Reach) has 42 attributes and point layer (Stations) has 7 attributes. My code is:
"...
2
votes
3answers
609 views
Projecting GPS point to point in closest pgrouting road (map matching)?
I'm quite new to PostGIS and pgRouting.
I'm interested in doing a simple map matching. Precisely, finding the closest point in a given OSM road network.
I’ve successfully imported the OSM network ...
1
vote
1answer
114 views
Intersection with closest point using PostGIS?
I'm trying to update the field of a point table with a value from a linestring one :
update object_elevation
set contour_elevation = c.contour
from contours c
where st_intersects(st_ClosestPoint(c....
