Questions tagged [point]

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

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5
votes
2answers
13k views

What are the units of the Distance Matrix tool results 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
2answers
8k views

Selecting features of vector layers based on another vector layer using QGIS?

I am using QGIS 2.12.2. I am using three vector layers (point, polyline and polygon shapefiles) of the region of interest. Any advice in making the selections from one dataset based on the other ...
1
vote
2answers
2k views

Get nearest line to point with v.distance in QGIS

I want to retrieve the nearest line to a point with the GRASS function v.distance(). But I think I do not fully understand how to use this function. What I have are two layers (in the same CRS -> EPSG:...
0
votes
2answers
202 views

Group points and compute area

In a point vector layer, how to compute area for 4 defined ranges of values of one attribute? On the example below, I want the total area for each of the 4 colours.
22
votes
2answers
10k 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: ...
23
votes
2answers
7k 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 ...
11
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2answers
2k views

Creating line (closest vertex to line) using ArcGIS Desktop?

I'm using ArcInfo 10 SP3. I am working in reorganising our utility data. Two years ago, we have started collecting Private Service water line. We still have a lot of them to extract from old ...
8
votes
1answer
5k views

Distance to nearest point for every point same SpatialPointsDataFrame in R

I have a SpatialPointsDataFrame that I'm working with in R. I want to add a new vector to the dataframe that contains, for every point, the distance to the nearest other point in the ...
3
votes
2answers
1k views

Total great circle distance along a path of points

I am looking for an SQL query that sums the distances between a series of points using PostGIS. The situation is as follows: I have 2 tables: tracks and points. Points belong to a track and thus ...
7
votes
2answers
711 views

Representing uneven tree canopy spread around point in QGIS?

I am trying to make an attribute to show the uneven spread of the crown of a tree using the four cardinal points. I can use a buffer to show one feature, in this case a root protection area. But I ...
8
votes
2answers
5k 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 ...
6
votes
3answers
2k views

Calculate distance between point and linestring and how to represent that on QGIS?

I have loaded my data with osm2pgrouting and I have my network with ways (Linestring) and nodes (Point). The problem is : I have a database of doctors addresses (point) and I should calculate the ...
3
votes
1answer
5k 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 ...
4
votes
2answers
3k views

Spatial Join in R

I'm fairly new to using R for spatial work so bear with me. I have found questions similar to this but nothing that answers this question specifically enough for me to implement it. I have point data ...
3
votes
2answers
10k views

Layers with same coordinates not lining up

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 ...
3
votes
3answers
723 views

How to delete duplicate LiDAR points?

How can I delete duplicate LiDAR points? I incorrectly read the same las twice and saved as a one file resulting in duplicate XY points. How should I delete these duplicate points?
10
votes
1answer
6k views

How does FlowMapper 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 ...
8
votes
2answers
1k views

Shortest path from points in one layer to points in another layer via roads in QGIS

I'm looking for a way to calculate the shortest path from addresses to subway stations via a network of roads. I have the Road Graph plugin, however, the addresses and subway stations are point ...
7
votes
3answers
2k views

Creating raster or vector raster from DEM point file?

i have a point shape of 75.000 elevation points in a regular 5 m grid. We now want to create a polygon grid with the elevation points as "centroids". Unfortunately, all attempts to do so fail: I ...
5
votes
2answers
7k views

Update point coordinates in QGIS after manually moving locations in edit mode

I have imported point coordinates from a database, but I need to manually adjust a lot of the locations. Is there a way for QGIS to automatically update the point locations in the attribute table ...
4
votes
4answers
811 views

QGIS Atlas generation for multiple map extents?

I'm trying to create 5 maps in composer showing the same layer features but different extents of a map (attached an image to give everyone an example). I've opted to use atlas to save me manually ...
4
votes
1answer
2k views

how to split a line by a point which is on the line but not in the linestring itself?

i need some help with the following: i have a linestring - geom i have $lat,$lon (using some php syntax) i have an osm table with the roads geom, i am trying to get closest point, and then split the ...
3
votes
1answer
830 views

How to get lines and nodes around the confluence point in a network system (line shapefile)?

I got a network line shapefile and the figure below was part of it. I want to do task around confluence point, so I took photo around confluence point as figure below. I want to get line segments (...
3
votes
1answer
3k views

Standalone Python script to split a polyline with a point layer

I have a polyline layer and a layer of points that are on top of the polylines. I do not have the ArcGis advanced license so I can't use the Split Line at Point tool. Can someone help me with a ...
3
votes
5answers
2k views

Find nearest point along polyline using 'sf' package in R

This is a follow-up question related to my earlier post about using the sf package to split polylines using nearby points. I have 450 points with XY coordinates and a large river network (~214,000 ...
3
votes
2answers
1k views

Convert raster to a CSV values and lat long based on raster value in QGIS

I am looking to convert a raster into a csv file (or tab delimited) based on values in the raster (Value > 0). The csv would have three values, latitude of center of cell, longitude of center of cell,...
2
votes
2answers
224 views

How to measure mean distance in search radius by PyQGIS?

I have a point layer with 250 features. I want to find mean distance for each point feature base on 500 search radius. In QGIS by "Distance Matrix" I can measure mean distance for each feature based ...
1
vote
2answers
1k views

Join Point to the Nearest Polygon

I'm using QGis 2.18.3 on Windows 10. I'm trying to join a point layer with a polygon layer. However, since it is a city grid map, points that do not fall within the polygons do not get joined. My ...
7
votes
2answers
4k views

Automating drawing of polygons (square) around number of points in QGIS?

In QGIS, how can I automate drawing a 100km x 100km square around a number of points, with the point being dead in the center? I'd need to loop through all the points and create a polygon, but not ...
5
votes
2answers
4k views

Getting polygon shapefile node coordinates and point order

I am trying to get the coordinates of each node of a polygon in QGIS. What I basically did is use the following tools: Vector -> Geometry tools -> Extract nodes Vector -> Geometry tools -> Export ...
5
votes
3answers
260 views

Finding redundancy between two layers

Let's say I have two point layers that contain locations of wells on a property. layer A has 50 points. layer B has 35 points. Some of layer B's points already exist on layer A, and some of them do ...
5
votes
3answers
9k views

Creating point to center of polyline?

I'm trying to create a points in the middle of polylines. The data is now in the form of shapefile. Is there an easy way to do this?
4
votes
1answer
359 views

Select points approx. 2000 metres from another point along a river?

I have a series of points representing a river network (See Image Above). Each point contains attributes on Latitude, Longitude, Z value and Length calculated using flow accumulation. The river ...
3
votes
3answers
1k views

Performing join on simultaneous spatial and attribute criteria in ArcGIS for Desktop?

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
2answers
4k views

How to count point shp inside polygon shp using Python?

This is my first time here, so I'll try to be as specific as I can. What I'm trying to do is found out which polygon contains the most points and write the result in a text file. Here is my script : ...
3
votes
2answers
3k views

Creating series of points along multiple polylines at once in ArcMap?

I have a series of polylines that represent linear vegetation (shelterbelts, etc). I need to convert these to a series of points equally spaced in order to add them to a different shapefile that ...
3
votes
3answers
404 views

Dynamically update points with xy coordinates in table

I have an Oracle database table with columns for 'X' and 'Y' coordinates. Now I want to display these points in ArcMap. I can use the 'Display XY data' tool for that. My table in the database with XY ...
3
votes
3answers
2k views

How to convert points to lines?

I want to convert these points to lines, however they are not sorted sequentially along a line (by ID or FID), i.e. the converted lines zig-zag across the obvious trail of points. How can I join ...
3
votes
1answer
2k views

WKT: What is the reasoning behind the concept of a POINT EMPTY?

In data formats like WKT and WKB, we have ways of representing "empty" geometries. That all pretty much makes sense: a "LINESTRING EMPTY" is a LINESTRING type with 0 vertices. Same with a MULTIPOINT, ...
2
votes
1answer
177 views

Create points symbology with more than one parameter

In QGIS i would like to create symbology for points layer where the symbology will take into account more than one parameter (currently two). i.e.: My points layer has street names and house numbers ...
2
votes
2answers
597 views

Using points2one?

I downloaded the points2one plugin and tried many times to connect points to a line, but it never works. Is there something that I set wrong? I tried the answer,but it has been running 10 mins, and ...
2
votes
2answers
2k views

Find nearest line segment to each point in R

I've seen similar questions, but not with R. I have a sf object with approx 500000 thousand points. I also have an sf object of lines. Each line has a unique segment number called 'segnum'. For each ...
2
votes
1answer
205 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 ...
1
vote
1answer
190 views

Snapping points to crossroads using ArcGIS Desktop?

I have some points (370 points) in a layer . These points must snap to crossroad layer . I could'nt find any tools in arcmap to snap points to crossroad layer. Is there any way to snap these points ...
1
vote
1answer
584 views

Using ArcPy to convert .txt to shapefile with coordinate system?

I tried to define my coordinate system on creating the shapefile but when I zoom to layer I don't see my features and ArcGIS crashes. I know it's not in the coordinate system I defined for it but it ...
1
vote
1answer
173 views

ST_DWithin query throwing 42601 error?

I am trying to get from a particular point more informations about the surroundings (which are also points). So I wrote this: SELECT * FROM osm_point WHERE ST_DWithin(way,(ST_SetSRID(...
0
votes
1answer
2k views

Merge two points of two different polygons to get one polygon at the end

I would like to join points from two different features. I already searched for plugins, but so far but didn't find one working plugin or solution for my task. So here is a picture of 2 polygons/...
14
votes
1answer
8k views

Converting Twitter tweets into points?

I've been doing some research on using R to datamine twitter, but I haven't really found an answer or a decent tutorial for my question. I'm interested in pulling tweets from twitter with a certain ...
11
votes
2answers
1k 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 ...
9
votes
1answer
6k views

Creating line from points using PostGIS?

I have a PostGIS table with position data of numerous vehicles and want to create lines from these points. Data can be selected by vehicle id and ordered by timestamp but how to create lines from ...