Questions tagged [delaunay]

A prefix to help define a type of mathematical transformation, such as Delaunay Triangulation, or Delaunay Tesselation

Filter by
Sorted by
Tagged with
0 votes
0 answers
15 views

Projection causes interpolation error?

I'm trying to do an interpolation with matplotlibs tri function, but the results show as empty for some reason. Specifically, I am trying to interpolate rainfall across an island given 41 weather ...
user avatar
  • 153
-1 votes
1 answer
258 views

Python implementation to generate Delaunay triangulation based spatial weight matrix [closed]

I'm looking for Python implementation for Delaunay triangulation based spatial weights. There are a lot of spatial weights techniques available in a Python geospatial library PySAL but Delaunay ...
user avatar
  • 249
2 votes
2 answers
160 views

Using GRASS v.delaunay with QGIS results with gaps in triangulation

When I use the GRASS v.delaunay algortithm in QGIS 3.18 on my dataset the output has gaps in it. But when I use the QGIS delaunay algorithm there are no problems and all is triangulated. The input ...
user avatar
  • 83
2 votes
3 answers
225 views

Making polygon layers always have area fields in QGIS

I am making Delaunay triangles of several (over 40) combinations of points and it is very tedious to output new shapefiles for each combination without even having the area of the triangles by default,...
user avatar
3 votes
1 answer
84 views

Delaunay triangulation returning empty geometry in PyQGIS

I would like to compute the Delaunay Triangulation for polylines. But sometimes it works and sometimes it does not, I tried with hand drawn lines. lines=QgsProject.instance().mapLayersByName("...
user avatar
2 votes
0 answers
648 views

QGIS export to 3d mesh format

I'm testing qgis triangulation. So far I managed to extract a single polyogon, simplify it, and convert to points. The problem is that the triangulation produces something unexpected. This is the ...
user avatar
2 votes
1 answer
325 views

Creating a 3D TIN or similar 3D Delaunay triangulation in R

Background: I have topographical datasets with height information as a starting point. The endgame is to create a dataset of triangulations which I can use to import into Parasolid to be used further ...
user avatar
0 votes
1 answer
319 views

Calculating delaunay triangulation with two diagonal lines using ArcGIS Desktop?

How do I obtain a line output similar to a delaunay triangulation but with two diagonal lines, from a point layer containing a regular-spaced point grid using ArcGIS Desktop? The current result is ...
user avatar
  • 2,218
1 vote
1 answer
73 views

Arcs from a Delaunay Triagulation

I am trying to generate a Cost Distance table using Spatialite. I have several points in the table random_points for which I would like to compute the Delaunay triangulation and use the segments it ...
user avatar
  • 53
2 votes
0 answers
105 views

Incomplete Delaunay triangulation unsing pyqgis3

I'm writing a small Qgis3 python plugin to convert polygon shapefiles to input files for a scientific model. I therefore need to split up the polygon geometries to more simple geometries with up to 4 ...
user avatar
  • 29
0 votes
1 answer
242 views

Match SpatialPoints to Delaunay Triangles in R

I have 2 SpatialPointsDataFrame files. I compute the Delaunay Triangles from the first shapefile (shp1) as in the code below. Then I wish to assign each point from my second shapefile (shp2) to one of ...
user avatar
3 votes
0 answers
85 views

Apollonius Graphs (Delaunay Graphs of Disks) in sfcgal or PostGIS?

I was wondering if there is support for Delaunay Graphs of Disks (a.k.a. Apollonius Graphs) in PostGIS/sfcgal? A CGAL function seems to exist for this. But I can't seem to find it in the PostGIS ...
user avatar
  • 10.3k
2 votes
0 answers
50 views

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 ...
user avatar
9 votes
4 answers
928 views

Minimum wall-thickness of a non convex polygon with holes

What is the most efficient way to find the minimal wall-thickness (value and location) of a complex, non convex polygon area including holes? See example of a polygon in blue, with the minimum wall-...
user avatar
4 votes
2 answers
1k views

St_delaunaytriangles polygon with holes

I'm using PostGIS to decompose a polygon with a few holes into triangles via st_delaunaytriangles. Unfortunately, it does not return the right result with holes, because the triangles being outputted ...
user avatar
6 votes
5 answers
3k views

Calculating Voronoi Diagrams for polygons

There are a variety of good algorithms for generating the Voronoi polygons or their complement, the Delaunay Triangulation for a set of points. My question is simply, is there an algorithm for ...
user avatar
  • 331
3 votes
2 answers
235 views

Query Z at intersecting point locations from a MultiPolygonZ?

I create a MultiPolygonZ geometry with ST_DelaunayTriangles(). select st_setsrid( ST_CollectionExtract( ST_DelaunayTriangles( ST_GeomFromText('MULTIPOINT ...
user avatar
1 vote
1 answer
668 views

Constrained Delaunay Triangulations in PostGIS?

It is possible to make Constrained Delaunay triangulations in PostGIS (PostgreSQL)? I have a Polygon and I need to make internal triangulation like this: I tried to use ST_DelaunayTriangles but is ...
user avatar
  • 61
1 vote
0 answers
766 views

How to Create Voronoi Polygon Diagram within surrounding polygon?

I want to create a Voronoi Diagram within an outer polygon. I want to retrieve a result very similar to this solution, which uses ST_DelaunayTriangles() to create Triangles. Actually, it would ...
user avatar
  • 51
3 votes
0 answers
60 views

Calculating a new attribute for a polygon based on its corners

i have a pointlayer with a real number as attribute named amount. I want to calculate and visualize the difference of amount between neighbourhood points. So first I made a delaunay triangulation ...
user avatar
4 votes
1 answer
434 views

How do I create line vectors with a new ID from points in QGIS?

I have a list of stations from which I would like to create a network of lines (the one created with the Delaunay triangulation would be fine) identified by a particular ID (for example, "AB" for the ...
user avatar
5 votes
3 answers
2k views

How to set up a threshold for Delaunay triangulation?

I've been working Delaunay triangulation on a set of random points inside a group of mostly linear areas (in fact, buffers around rivers). The problem is that while the triangulation works correctly ...
user avatar
  • 389
1 vote
0 answers
147 views

Delaunay Triangulation on labeled data

I have a table with locations and labeled data and I need to apply Delaunay Triangulation on specific labeled rows. For example, I have some locations labeled as schools, hostels, gardens, ... and I ...
user avatar
  • 53
1 vote
1 answer
481 views

Extracting coordinates of a triangulation from DEM data

I'm working on the succinct representation of planar graphs and now I'm trying to obtain some datasets to test my results. I saw that Delaunay triangulations of elevation data can be a good source of ...
user avatar
1 vote
1 answer
110 views

How to identify Sliver triangles in a TIN surface and count them? [closed]

Is it possible to count slivers in a TIN? I generated a Delaunay triangulation surface model and i want to know how many slivers the TIN has.
user avatar
  • 11
1 vote
0 answers
184 views

Contours from delaunay triangles

I have generated a delaunay polygon file that represents terrain data. Is there a way I can produce contours from the polygon file? I know I can convert the polygon to an Esri TIN, and then produce ...
user avatar
  • 9,213