I´m new to QGIS, lately I got 2 Shapefiles one showing the polygons for some areas that represent street blocks, and another shapefile with the points that represent the number of comercial stores in the area, so sometimes we have one and others we have 90, depending on which street the survey was done.
The problem is that the points layer shows only one point where there should be more than one, that is because all points corresponding to a certain street or block are asigned the centroid of that polygon as coordinates. Is there a way to distribute all points automatically inside the polygons so if there is only one the points stays in the centroid and if there are more the points shift position in order to show how many points are exactly? Added a screencap for references
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I have two layers, the first has hundreds of polygons all with a unique id.
The second one has thousands of points all with a unique id
Each point has a "area of influence" or a radius of 2 miles.
I need a "list" of all the polygons touching (no need to fully cover) each point's area of influence.
My goal is to have labels in the center of polygons.
Currently the polygons are being added via a vector tile source.
In order to have labels centered on polygons, it seems I must add a point source that has geometries representing the polygon centroids. (based on this answer)
When getting geometries via vector tiles, would it possible to dynamically create this point source, or must it be another vector source, one dedicated solely to centroid points?
The usual approach is to generate the labels separately, using geojson-polygon-labels.
Attempting to do it dynamically would be pretty tricky, although perhaps not impossible.
I am trying to see if there is a plugin or Node library that will be able to estimate a lat/long based on an array of distances from known locations. Attached image shows three circles which are radius from known location. I would like to take this information and estimate a location from the combination of information. Originally I was thinking of just showing the intersect of the circles, but that does not cover cases where the circles do not intersect.
I am designing a water supply distribution network. I have various pipes represented by Lines. Each start and end point of Line is a Junction (Node).
I have created Thiessen Polygons (Voronoi) using QGIS for each Junction (The Thiessen Polygon represents flow area for its corresponding Junction.)
I also have various Ward Boundaries (also represented as irregular Polygons), with each Ward having different Population.
My requirement : I want to calculate area of intersection between each Thiessen Polygon and each Ward and get a table, so that I can calculate the exact population within each Thiessen Polygon.
Example of Thiessen Polygons (The Dot within polygon represents corresponding Junction) :-
Example of Wards (also represented as Closed Polygons) :-
Final output desired :-
I have found the solution in ARCGIS -> Intersect Tool where it intersects Two Shapefiles (each having multiple polygons) and gives intersection results.
I think the same is not possible in QGIS as of now.
Is there a way in Turfjs to determine the co-ordinates at which a LineString intersects with the border of a polygon?
There's a number of ways to find out if a point is within a polygon and a number of ways to find out if a point is on a line and so on, but I can't seem to figure out a way to ask "at what point does this line intersect this polygon's border".
I could enumerate the points in the polygon using a line intersection algorithm to find that point but I was wondering if there's a more "turf" way of doing this.
For context, I've loaded a GPX track and want to estimate the location/time at which the track enters/exits a defined area.
Because a GPX track only records locations at specific intervals it usually the case that pN recorded at time tN is outside the area and pN+1 recorded at time tN+1 is inside the area.
If I can get the point at which line (pN, pN+1) intersects the polygon's border I can estimate the exact time the track crosses into the polygon.
Ultimately, turfjs does not seem to have an API for doing this.
I was able to get the answer I wanted by enumerating the points in the polygon from the GeoJSON object to construct a sequence of line segments and then I used maxogden/geojson-js-utils linesIntersect function to test for intersection points.
I don't see a Turf function that does exactly that, but there is intersect, which finds the area of intersection between two polygons.
You could:
Construct a polygon by joining the line to itself reversed (so ABC becomes ABCBA)
Find the intersection of ABCBA and P, the original polygon using Intersect.
The intersection should be a zero-area polygon that is the part of ABCBA inside P. Somehow compute the length of it (strangely there's no perimeter function).
Subtract that length from the original length of ABC.
Not exactly elegant, true. :)
EDIT
Tried this. Turns out Turf-intersect doesn't return intersections if one of the polygons is zero-area.