Questions tagged [convex-hull]
Smallest bounding area for an object or group of objects with no concave angles.
103 questions
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Create boundary box without overlapping
Is there a way to create a tight boundary box around these shapes without creating a shape which will overlap other shapes which aren't the selected feature.
Creating a convex hull will create these ...
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QGIS buffer concave at the front and rounded at the back
I have point layer, where points are grouped into groups - every feature has point_id and group_id. I want to generate around group of point buffer (for example 1500 meters) where front of points ...
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Drawing convex hull that joins centroids of four nearest clusters with highest values
I have point layer in which I have calculated the DBSCAN clusters.
The field that stores the clusters is called 'class' and the values range from 1 to 9, plus NULL values.
As you can see in the ...
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Differentiating with unique id overlapping/intersecting or isolated convex_hulls in QGIS
From a layer of 2000 points, I have a field with the name 'NUCLEUS' with four categories (1, 2, 3, 4) that identifies each point with a category of density clusters. In red color you can see the ...
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Get convex hull of polygons if they are within a certain distance of each other otherwise leave their geometries alone
What the question says, I want to join geometries together (as a convex hull) if they are within a certain distance of each other, and leave them as separate geometries if they have no neighbors ...
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How to create a convex hull set polygons conditioned by a minimum number of points and a maximum distance
With the following expression I am trying to create a set of convex hulls from a layer with a point geometry that complies two variable conditions: a minimum number of points can be declared and a ...
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Convex hull geometry issue
I have a lot of polygons which have a notch at the edge. I want to have the area of the notch for each polygon. In order to reach this goal I used the Convex hull tool and then clip the polygons (...
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How to change the Point Cluster circle symbol to a convex hull
I am using the expression presented by the user JGH to solve the question 'Point Clustering in QGIS, but values show a percentage and not count of points'
This shows my example:
As you can see I use ...
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Uneven polygon from points with sf package [R]
I have created a group of polygons from a data frame with that code :
P <- P %>% st_as_sf(coords = c("lon", "lat"),
crs = 31370) %>% dplyr::...
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Filtering points appearing in list of convex hull polygons
I have two DataFrames df & df1:
df: containing latitude, longitude, and binary cluster (0 or 1)
latitude Longitude cluster
30.400091 -100.722830 0
30.500091 -100.762830 0
30.600091 ...
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QGIS minimum bounding geometry expression
I would like to receive the polygon of a convex hull of a group of points in a layer, grouped by its name. Exactly the same result as the "minimum bounding geometry" tool does.
This needs to ...
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QGIS: Minimum bounding geometry: Convex hull not including all features
I have been using the convex hull tool to create MCPs for various layers (containing location points). For some reason, this layer is not looking like the others and I can't figure out why. It's as if ...
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Converting convexhull polygon from GeoDataFrame to shapefile
I have a point GeoDataFrame with a "class" column. I wanted to make a convexhull for each class and then write it as a shapefile, but I got an error in converting it to a shapefile.
print(...
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Cluster & Average linestring based on similarity
I am looking for a way to find the "average" linestring of a set of linestrings using postgis 3. Ideally the collection of linestrings should be clustered based on their similarity (Perhaps ...
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Splitting concave polygons into convex polygons in QGIS
I want to optimize and decompose several concave polygon into convex ones but not too small or to complicated ones.Ideally cutting in places that would minimize the creation of convex polygons and in ...
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Computing concave hull from points using PostGIS and display in QGIS
I'd like to create a boundary of a set of point using ST_ConcaveHull function in PostGIS
My query works fine and I can see the polygon through the geometry viewer embedded in the pgadmin.
CREATE TABLE ...
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Crown area calculation with lidR::.stdmetrics differs from raster::area
I found out that tree crowns delineation using lidR::.stdmetrics calculates an area that is different from the area calculated by raster::area() or QGIS with the field calculator $area function.
The ...
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Creating the minimum convex hull that contains certain percentage of points in QGIS
I'm working with QGIS 3.16 Hannover. I've got a point layer (shapefile) with 3,000 features and I want to create the smallest convex hull that contains 90% of those points. Well, ideally, I would like ...
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Extracting convex_hull polygon from CSVwith scipy.spatial ConvexHull and output it to a shapefile
I'm looking for a Python solution for extract a convex_hull polygon from quite big CSV (nearly 150 millions points) and return back the polygon to a shapefile.
After reading the CSV with pandas (pd....
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Filling in gaps between polygons using PostGIS functions
I have a similar question to Filling gaps between polygons using QGIS
The solution talks about using it in QGIS but I want to use PostGIS functions on a table on the geometry column.
The solution ...
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Convex hull that follows irregular points distribution
Based on an irregular distribution of points (longitude,latitude), I obtained the convex hull below (I use saga_cmd with polygon convexity in 1). Would you have a way to create a convex hull that ...
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How to create a convex hull using QGIS Geometry Generator?
Background:
At 3.14.16, I'm trying to learn a little more about Geometry Generator, in this case convex hull. I created a simple test point layer with six points. I then used Geometry Generator with ...
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Issue with using minimum bounding geometry tool with points in QGIS
I am attempting to create a 100% MCP in QGIS using the minimum bounding geometry tool in QGIS. My data is sensitive and I therefore cannot share any of it (including a subset). I have used a dataset ...
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Geom and ST_AsText(geom) gives different intersection results for same geometries [duplicate]
I am working to get the count of points intersecting with a convex hull. When I use the query in 1 it gives a count different from the count in query 2. Only difference is that in query 1 I am using ...
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ST_ConvexHull excludes some points
I'm trying to create convex hull for about 25000 points stored in the table.
ST_ConvexHull run successfully, but resulting geometry does not covers some points.
What could be a reason?
And it is not ...
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Obtaining coordinates of convexhull polygons using DBSCAN and CONVEXHULL
I am using DBSCAN to cluster coordinates together and then using convexhull to draw 'polygons' around each cluster. I then want to extract the coordinates of the convex hull objects. However, the ...
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Computing convex hull of points using shapely
I have a points shapefile and I want to compute the convex hull of the points using shapely, and output the result as a shapefile using Fiona.
Does anyone know how I can do that?
This is what I have ...
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Convex Hull in GeoPandas
I have a shapefile with a number of points. Using GeoPandas, I am trying to create a convex hull around the set of points. However, my output layer returns the same points as were fed in.
My ...
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Creating convex hull by expression by aggregating points
I would like to recieve the centroid of a convex hull of a group of points in a layer, grouped by its name. This needs to be done by expressions, available in QGIS 3.4. E.g. I have this list of points:...
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Creating convex hull of set of points using QGIS
I have a shapefile layer with a set of points.
I would like to enclose them (or turn them) into the polygon (with the line in the middle).
I tried this:
Converting cluster of Points to Polygons ...
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Selecting random points from specific attribute in yield map using QGIS
I am using QGIS.
A farmer has sent me the shapefiles from his John Deere combine. They were three shapefiles that I have merged into one layer. The shapefile is from one field with a treated ...
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Convex Hull not outputting expected number of features
I have a .csv file with observations of various species and I want a polygon to illustrate the area where those species occur. I ran the Convex Hull, grouped by the species' names field, which ...
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Creating minimum bounding geometry using the convex hull method in R
I would like to create a small enveloppe around a set of polygons that encloses around them. I would like to avoid using the bounding box function (example below) because it would be too big. Rather, ...
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Calculating Convex Hull based on attributes in QGIS
I have a layer with lots of (spatially grouped) lines - lines belonging to a group share the same value in a field.
I would like to create convex hulls around each of these groups using QGIS 3.8.
I ...
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PostGIS- convert points to polygon based on multiple shared attributes
I have a PostgreSQL PostGIS point table (not multi-points). I want to convert the points to polygons (using convex-hull?) grouping the points by shared attributes from 2 columns.
In this example, '...
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Using convex hull for interpolation of individual plots or lump plots together in ArcMap?
This question is inspired by Using kriging to extrapolate values outside of sampling polygon in ArcMap?
I'm working on a project trying to understand the lasting effects of historic scientific ...
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Knowing/converting AREA, PERIMETER units in QGIS?
I use Convexhull tool in QGIS and there are result value :
AREA = 0.0017494390 PERIMETER = 0.1725495172
I thought the result was strange. So, I took a rough estimate of the points through the ...
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Minimum Bounding Geometry Convex Hull
I have 1000+ irregular shaped polygons where I would like to determine the orientation (azimuth) of their long axis. The polygons overlap in a few cases, if that matters. I am using the Minimum ...
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GRASS v.hull for many point sets
I have map "my_pointmap" with 3D points with ids=(1,2,3...N). I have also list of subsets of these point ids , S = [(1,2,3,4),(2,4,10,12), ...]. I would love to get GRASS GIS vector map with |S| 3D ...
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Creating Polygon from groups of points
I have a point feature class (Address Points) and I am interested in creating a polygon feature class around groups of 500 address points. Is there a way I can do this programmatically, as opposed to ...
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Converting trajectory to outer edges polygon
Using PostGIS, I'm trying to solve the following problem:
I have trajectory data (coordinates from API query), like on this image:
and want to convert it into polygon, having only outer edges:
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Defining convex-hull of (clouds of) points using R? [closed]
I have multiple (clouds of) points, and would like to take the outer envelope of these points. This will allow me to polygonize my points.
Using the convex-hull would help me, but in some cases, my ...
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Compute convex hull of points in a feature collection [closed]
I uploaded an asset (which was originally a shapefile of points) and imported it into my script as a feature collection, with each point being an independent isolated feature.
I would like to compute ...
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Creating Minimum Convex polygon around points in QGIS
I just downloaded QGIS 3.0.2 and trying to create a minimum convex polygon around points using the "Minimum bounding geometry" (convex hull).
The videos and help documents I see online ...
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Polygons hull QGIS [duplicate]
I'm currently working with old french cadastre on QGIS, I've vectorised it and now I want to tile it. I've georeferenced it, but it's not sufficient for a great result. To improve the result, I would ...
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How to create a convex hull in R based on the larger of two shapefiles' extents?
In R, I have two shapefiles: Shapefile A represents roads (polylines), Shapefile B some location (points). I want to plot the convex hull enclosing the study region, and it has to be set to the larger ...
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Convex hull area: what are the output units?
I have what I hope is a simple question. I'm doing convex hull calculations. What I have is area(convex_hull($geometry)).
I get a number and that's all well and fine. Since I need to get a ratio of ...
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DBScan with Convexhull
I am new to GIS, I am using PostGIS(2.3). I have two problems I am not clear with
Problem-1: I have list of locations(longitude, latitude, 4326), what is best/correct projection to use while ...
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How to create view from ST_ConvexHull
I have a simple SpatiaLite DB containing one table with point features. I would like to generate a Minimum Convex Hull around that features. I could do that easily with one of the Convex Hull tools ...
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LoCoH or TLocoH home range estimators in ARC?
Is there a way to create a Getz and Willmers Local Convex Hull in ArcMap? The "Minimum Bounding Geometry" tool is insufficient for my purposes, as it greatly overestimates the sizes of home ranges.
...
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