Questions tagged [point]

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

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49
votes
7answers
112k views

Getting list of coordinates for points in layer using QGIS?

I've got a layer in QGIS that is comprised of points. Its attribute table doesn't have (show) the corresponding x and y coordinates for each point. Is there a way for me to extract a list of ...
24
votes
11answers
69k views

Extracting raster values at points using Open Source GIS?

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.
8
votes
3answers
5k views

Normalizing point cloud data

How I can get Digital Height Model (only object heights, DSM - DTM = DHM)? Many applications can do this, but they convert it to GRID or TIN format. I was wondering if it was possible to keep the ...
35
votes
6answers
22k views

Joining 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 ...
23
votes
7answers
43k views

Creating points in specified distance along line using QGIS?

I want to use QGIS creating points along the line, but in specified distance. I found two GRASS tools in SEXTANTE Toolbox: v.to.points v.segment I tried v.to.points, setting the maximum distance ...
14
votes
4answers
19k views

Nearest distance between point and line layers in QGIS

I have two layers, a line and a point layer. I need to make a line layer which connects all the points to the nearest line feature. How can I do that? Is there a plugin available for QGIS? This is a ...
17
votes
1answer
11k 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 ...
16
votes
6answers
17k views

How to randomly subset X% of selected points?

What methods are available in ArcGIS 10.2 to randomly subset a selection of points. For example, in the attached screenshot I am interested in keeping 20% of the selected points and deleting the rest....
26
votes
9answers
18k 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 Excel's ...
30
votes
7answers
10k views

Calculating intersection of two Circles

I'm trying to figure out how to mathematically derive the common points of two intersecting circles on earth's surface given a center Lat/Lon and a radius for each point. For example, given: Lat/Lon ...
17
votes
4answers
24k views

Converting Polygon into single or all Points using QGIS?

I want to convert polygons into points using QGIS. I know how it's done in ArcGIS Desktop.
12
votes
3answers
10k 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 ...
34
votes
10answers
10k views

Creating regular point grid inside polygon in PostGIS

How to create, inside a polygon, a regular grid of point spaced x,y in PostGIS? Like the example:
65
votes
12answers
154k views

Creating point features with exact coordinates in QGIS?

How do I create point features with exact (manually entered) coordinates in QGIS? I get precise GPS coordinates from a survey team which I need to add to a point layer. What I want: -Add point, type ...
10
votes
3answers
3k views

Converting point layer to raster grid that shows frequency of points per cell uisng QGIS

I have a point layer that shows the distribution of a species. Is it possible in QGIS to convert this point layer to a raster grid in which the value of each cell corresponds with the amount of ...
34
votes
3answers
72k views

Draw lines from points in QGIS

I have a point layer and need to draw a line passing through or in the vicinity of the points (up to 0.5m ditance between the point and the line). The nodes of the line will recieve the attributes of ...
17
votes
4answers
4k views

Seeking algorithm to place maximum number of points within constrained area at 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
4answers
16k views

Get all the points of a polyline

I have some polyline feature objects in python. Now I want to get all the points of polylines. For example, if a polyline has start point [0,0] end point [5,5]. Result: [1,1];[2,2];[3,3];[4,4];[5,5]...
10
votes
1answer
19k views

Creating DEM from Point Data using QGIS?

My boss gave me a small 3D-point-shapefile and asked me to make an DEM from it, which I should put together with an older DEM of the same site, which was made with Surfer. I created a raster-layer ...
8
votes
6answers
31k views

Representing several points with same coordinates on map using ArcGIS Desktop? [duplicate]

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 ...
7
votes
3answers
7k views

Adding “noise” to overlapping X,Y coordinates so no longer in 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 ...
41
votes
7answers
18k views

Comparing 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 ...
14
votes
2answers
6k 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 ...
23
votes
5answers
39k views

Finding distance of point along polyline using ArcGIS Desktop?

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 ...
4
votes
3answers
8k views

How do I plot points as graduated/proportional circles in R?

I'm back again with more R mapping questions! This one is concerning symbolizing points by a certain attribute with graduated/proportional circles. DATA: My full code can be found here if you're ...
9
votes
3answers
15k views

Retrieving start and end point coordinates with ArcPy? [closed]

How do I retrieve start and end point coordinates with ArcPy for a polyline feature class? I expect to pass a segment identifier to a subroutine and have it pass back start and end coordinates. The ...
9
votes
2answers
1k 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 ...
16
votes
2answers
4k views

Detecting if point is on left or right side of line in PostGIS?

I have a linestring table and a point table in postgis. I know the closest line to any given point. What I need to know is on which "side" of that line is the point. I guess I have to do that by ...
8
votes
3answers
5k views

Drawing lines from two points in CSV using QGIS?

I have a CSV file where one line looks like this: Duration, user, lat-start, long-start, lat-end, long-end 298, Casual,38.9101,-77.0444,38.91554,-77.03818 Each row in the CSV has two points and I ...
6
votes
4answers
3k views

Generating start and end points for LineStrings

I want to create start and endpoints in QGIS for a Linestring shapefile. I tried using the "QChainage Plugin" but was not useful. Can someone suggest a tool?
11
votes
2answers
6k views

Is it possible to create a point within a Polygon (not a centroid)?

Is it possible (without writing Python code - sorry I'm not a developer) to create a point layer from a polygon layer but ensure the point is within the polygon? The ftools centroid tool is cool but ...
5
votes
5answers
847 views

Creating all possible line segments between all points using QGIS

I want to connect all points in a point feature with every possible line segment using QGIS. For example, how a pentagon has five points with ten line segments connecting them all to form a pentagram ...
14
votes
1answer
3k views

How can I transform polylines into points every n metres in PostGIS?

Question in pretty much the same as this, but I need to use PostGIS. I have a number of polylines, and want to trasform them into points every n metres along these lines. edit: Thanks a lot to ...
9
votes
2answers
205 views

Convert vertices of polygon features to points using Virtual Layer in QGIS

I have a polygon layer and want to use a Virtual Layer that creates points from the vertices of the polygon layer. The question is how to write a query that does this? I am aware of the tool "...
7
votes
2answers
7k views

How to calculate distance from POINT to LINESTRING in R using `sf` library and get all POINT features from LINESTRING where distances were calculated?

I'm trying to calculate distances from a set of POINT features (1, 2, 3, 4, 5, 6 & 7) to a LINESTRING feature using sf library in R. I could calculate all the distances using the function ...
2
votes
2answers
4k views

Distance between points along polyline ArcGIS for Desktop?

I'm using ArcGIS 10.3 (Desktop), and I'm trying to measure the distance between points following a path determined by a set of polylines. Hand measurement is not a viable option-- there are ~7500 ...
11
votes
3answers
8k views

Removing small “salt & pepper” polygons from layer in QGIS?

I have a map made up of multiple polygons, with a few hundred thousand points very small polygons on within it. I need the larger polygons, but not the points small polygons. How do I select and ...
7
votes
1answer
9k views

Converting points to raster in ArcGIS?

How do I create such map from point data? I am using ArcGIS 9.3 and 10
1
vote
4answers
3k views

splitting a lines layer using points

I'm looking to accomplish a similar task to this thread: Splitting line at point positions using QGIS? Using QGIS and the Processing and GRASS toolboxes available, I'm looking to split a vector layer ...
5
votes
1answer
697 views

Prevent the Feature Attributes dialog box in QGIS

Any time I am inserting new point feature in QGIS, the Feature Attribute dialog box is popping up. Is there a way to prevent it? (I am willing to insert many points at once and this pop up box slows ...
5
votes
3answers
3k views

How to visually sort the order of Points with QGIS, GDAL, …?

The following Points layer is the basis of a rendering in a Android application. Android allows to draw a shape from the provided points. I cannot use LineStrings. However, the order of points ...
5
votes
2answers
14k views

What are units of 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 ...
14
votes
2answers
12k 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 ...
11
votes
1answer
22k views

Manually editing point coordinates in QGIS

Is there a tool for shapefiles or a QGIS Plugin available, which will enable me to edit the coords of a point manually ? ("tool" -f1 "Tsunami Gauge"-move x1.abcdef -to x2.ghijkl) ...
11
votes
5answers
26k views

Creating polygons around extent of similar points using ArcGIS Desktop?

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 ...
8
votes
1answer
3k views

How to create linestrings with a definite angle and length, that are fixed to a point

I want to create linestrings with a definite angle (e.g. 160°) and length (e.g. 2m) that are fixed to a number of points of another linestring. So, I want to use the ST_DumpPoints function to find the ...
8
votes
1answer
3k views

Split polyline by point using 'sf' package in R

I'm learning the sf package in R and would like to locate about 450 sites along the nearest reaches of a river network and to obtain the upstream and downstream distances along the reach where the ...
10
votes
5answers
15k views

How to extract POINT from a [LINE|MULTILINE]STRING

I'd like to create a vectorLayer in QGIS to display all the points that form a LINESTRING or a MULTILINESTRING stored in a PostGIS DB. I think that I need to transform all points of LINESTRING (or ...
0
votes
2answers
4k views

PGROuting 2 : Getting nearest node to a given point (with lat - long given)

I have a point whose latitude and longitude (only) are known, and a table of nodes with their geom. I want to find the closest node in the table to the given point. I think I can achieve this with ...
10
votes
2answers
4k views

Finding centre point of a raster in ArcGIS?

If I have, say, a rectangular and georeferenced raster file loaded in an ArcMap 10 document (.tiff w/ associated tfw), how do I easily find its centre point and store that point in a points vector ...

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