Questions tagged [point]

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

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11
votes
2answers
2k views

Creating random points along polyline in QGIS?

I am trying to create random points along a polyline shapefile in QGIS. Basically, like the 'random points' tool in 'research tools' but for polylines instead of polygons. I have tried converting ...
6
votes
4answers
7k 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 ...
11
votes
4answers
6k 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 ...
10
votes
2answers
3k 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)
9
votes
2answers
2k views

Show only one label for multiple points with same value in QGIS

I have a point shapefile which has for a few occasions multiple points with the same ID. Doesn't look nice with the normal label-display. Is it possible in QGIS to only display one label then? I ...
7
votes
1answer
384 views

Connecting centroids of lines sharing same intersection in QGIS?

I have this street network of the center of Turin (IT), composed by lines representing streets, and black points representing intersections. I have computed the centroids of each line and displayed ...
7
votes
1answer
788 views

How to group 10k points into closest pairs?

I was first faced with a problem of grouping 1000 pairs into unique pairs to minimise the total distance - since this was a small number I solved it using linear optimisation: Part 1 - Basic/Naive ...
7
votes
2answers
4k views

How to extract value from a raster based on lat and lon?

I have several netcdf files that I can read using the netCDF4 library in python. The data is gridded in 4320 rows and 2160 columns. I also have a list of lat/lon (in decimal degrees) and I am trying ...
6
votes
2answers
4k views

gDistance to determine closest point to polygon: does changing projection change results qualitatively?

I'm using gDistance from the rgeos package for R to find the nearest point to a polygon. The projection of both points and the polygon is +proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,...
6
votes
2answers
779 views

Increasing marker size based on number of points at same location in QGIS

I have a dataset that contains many points (representing specimens) with GPS locations taken at the same point. When I map these points as a vector layer, only the uppermost point shows - so, at one ...
4
votes
1answer
16k 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 ...
13
votes
3answers
4k views

PostGIS raster value of a lat/lon point

I have a tiff raster in my PostGIS 2.0 database. I want to get the value of the raster at a specified lat/lon point. I have: postgresql-9.1 postgis-2.0-svn with raster support a raster imported ...
11
votes
1answer
431 views

Point sampling along a pole-wrapping coastline with PostGIS

I am working on a task that requires me to get sample points every 1000 km along coastlines, and have run into a problem with Antarctica. From what I can tell, it seems to be an issue with the use of ...
10
votes
2answers
15k views

How to remove duplicate point features?

I have created many .gpx datas with my Garmin device, but due to the amount of data, I have imported the mapping data from my device several times (also because I didn't want it to be lost)... As a ...
6
votes
9answers
13k 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 ...
5
votes
1answer
278 views

Creating a point corresponding to the maximum elevation of a DEM [duplicate]

I am wondering how can I create a point corresponding to the maximum elevation value of a DEM. I mean, from the DEM I can easily get the maximum elevation. For the sake of a viewshed analysis, I would ...
5
votes
2answers
628 views

Saving centroid with attribute fields in PyQGIS?

I'm new in PyQGIS and wrote a script to read a polygon and get the centroid: from qgis.PyQt.QtGui import * from qgis.PyQt.QtCore import * # insert the location of the shp layer = iface....
5
votes
3answers
504 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 ...
4
votes
2answers
5k views

Compute Angle of line in conventional bearing using ArcGIS API for JavaScript?

I am trying to compute angle between two lines (line segment) using ESRI (ArcGIS, JS) in conventional bearing (Eg: N29'E) I am using Add Toolbar to draw a line segment where point A is a fixed point (...
3
votes
1answer
6k 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 ...
3
votes
3answers
2k views

Draw line between points from multiple datasets

I have 2 point datasets and want a tool or script to draw a line between all points in one dataset to all the points in the 2nd dataset. Is it possible? I have tried ESRI "Point Distance" and "...
2
votes
2answers
2k views

Calculate distance to points along line in ArcMap?

I have two shapefiles: a series of points and a polyline created from the points with the tool Points to Line. Both shapefiles have the same projected coordinate system with a linear unit in metres. ...
2
votes
2answers
4k views

How to create a graphic point by xy value?

I have implemented this code to create point event layer by xy text file, however I'm wondering how to create a point graphic by xy value? This script draws point graphic by mouse down. When I steer ...
10
votes
6answers
19k views

ERROR 000212: Cannot create XY event source Failed to execute (MakeXYEventLayer)?

I have a csv file that is 133mb in size and has over 1.3 million lines of data. Each line of data has its own lat/long and I was wondering what would be the best way to display those points based off ...
10
votes
2answers
4k views

What is a multipoint shapefile?

What is the difference between a multipoint shapefile and a point shapefile. in the creation of a shapefile In ArcGIS it has the choice of point shapefile and multipoint shapefile. But I do not know ...
9
votes
4answers
9k 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 ...
8
votes
1answer
8k views

How connect points with lines in QGIS?

I need to connect points with lines in QGIS. I am in this fresh out so I'm not sure how to do it and I need a little bit help with this. I read several posts and I tried to do something about it but ...
7
votes
1answer
1k views

How to connect particular sets of points with (poly)lines?

I have a timestamped point-table representing GPS-tracked places of different cars. To distinguish the cars there is a car-id for every point. So, a simplified version is looking like that: Now, I ...
7
votes
1answer
2k views

Is there a way to interactively rotate labels in QGIS using any of the edit tools? [duplicate]

I seem to have put too much detailed information in my previous question, confusing the masses. My apologies. Let me try again from a different angle. I want to rotate labels interactively/visually,...
6
votes
2answers
4k views

How to interpolate a lat/long point between two others at a given distance

I'm trying to solve the problem of interpolating a point at a given distance (in meters) between two other lat/long points. (e.g. P1 (50,10), P2(50.01, 9.990), I want to interploate P3 at a distance "...
6
votes
1answer
3k views

Creating polygon from exterior points using PostGIS?

How to convert points data to polygon, so as to form polygon from exterior point as shown above
5
votes
2answers
19k views

How to calculate new point coordinates from distance and angle using ArcGIS SDK for iOS?

I want to calculate the coordinates of a new point. What I have: The source point coordinates, the distance (meters) and the angle For example: I want to create a point within 100 meters and 45 ...
5
votes
4answers
2k 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, AC...,...
4
votes
2answers
2k views

Drawing lines between all possible combinations of points using ArcGIS Desktop?

I have a shapefile with several points (A, B, C, D, E,...) and I want to draw a line between all possible combinations of points (A-B, A-C, A-D, B-C, B-D,...). As I know that it is quite simple in ...
4
votes
2answers
1k views

How to randomly move points?

I have a feature class with a large amount of points. My purpose is to randomly move these points to see what happens as a result. Are there specific tools or Python programming methods to accomplish ...
4
votes
2answers
867 views

Selecting set number of points within polygon grid cells using QGIS?

I have a polygon grid with 1 square kilometer area cells, and over it a set of points, like so: What i need to do is select and extract only a single random point per grid cell. I could do that ...
4
votes
1answer
195 views

Changing the coordinate value of a Pointz object with python

How can I change the X,Y or Z value of a Pointz feature with python in QGIS? I am trying to change the Z values of Pointz with a python plugin. I am first trying to pass the selected feature to a ...
4
votes
6answers
46k 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 ...
4
votes
1answer
6k 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 ...
4
votes
1answer
2k views

Update xy fields when I move points?

I have a point shapefile in edit mode, containing x and y coordinates. When I move the point to another location, the x and y coordinates do not update to the corrected location. I realize the x and y ...
4
votes
1answer
4k 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 ...
4
votes
5answers
4k views

Finding center point of MULTILINESTRING using PostGIS?

How to find the center point of MULTILINESTRING, which lies on the multiline? I am using SQL in PostGIS
3
votes
1answer
2k views

How to generate random points with minimum distances between points in multiple polygons

I am looking to create random points for a random stratified survey. There are three different categories being surveyed; for each, I have a single shapefile, each containing a number of polygons. I ...
3
votes
2answers
2k views

How to do a Point to Polygon analysis with multiple variables in QGIS?

I have a database of almost 10k crimes, which are divided in to 10 categories and plotted on a map I also have a database of 12k addresses, which are also plotted on the map. I aim to perform a ...
3
votes
1answer
3k views

Getting raster values for large number of point features?

I have several projects with tree point features (SpecialStatusSpeciesPoint) that contain up to 2,000,000 records. I am trying to record tree height (Hgt) and base elevation (BaseElev) values, based ...
3
votes
1answer
641 views

How to create a line with start and end points which are in another layer in QGIS?

In my map, there are lots of points in layer A. I want to make a line layer B and I want to make start & end points of lines snapping to points in layer A manually. Can I use points of layer A as ...
3
votes
1answer
102 views

Quartiling a vector buffer in QGIS 3.6

I am evaluating Hurricane data that has a radius which 64kt wind speeds were observed for a specific event. The properties of a Hurricane dictate that the wind speeds change in each part of said ...
3
votes
0answers
694 views

GeoSever PointStacker Renders incorrect position [closed]

I've been trying the GeoServer Rendering Transformations - Point Stacker. According to this docs there's an optional cellSize parameter for setting the "Size of the cells in which to aggregate points, ...
3
votes
1answer
993 views

GeoDjango - save two Point fields, one for geography and one for geometry

Most of the explanations I've read for geography and geometry seem to suggest that one must only use either geometry or geography, and that the only way to use both is to cast/convert between one and ...
2
votes
1answer
266 views

Comparing point pattern and raster data?

I have a simulated data set showing distribution of a certain habitat type as a point pattern. Then I have a empirical data set but there the format is raster. The two datasets are covering the ...