Stack Overflow
Stack Overflow

Questions tagged [quadrilaterals]

14 questions
2
votes
1 answer

matplotlib unstructered quadrilaterals instead of triangles

I've two netcdf files containing both unstructured grids. The first grid has 3 vertices per face and the second has 4 vertices per face. For the grid containing 3 vertices per face I can use matplotlib.tri for visualization (like…
Mattijn
  • 12,975
  • 15
  • 45
  • 68
1
vote
1 answer

Transform quadrilateral into rectangle/square (in C#)

I have a quadrilateral with corners P1, P2, P3 and P4, all of which I know. I also have the output coordinates I want to warp these to (Q1, Q2, Q3 and Q4), which are a square of size 1. How can I make a function that "warps" an input point P to an…
aouni
  • 11
  • 2
1
vote
1 answer

Corner points of a quadrilateral from a set of grid points

I am given a set of grid points (defined by their x and y coordinates) that make up an arbitrary quadrilateral. I want to be able to find which of these points are the corner points. I have been looking at minimum bounding problems, however in my…
Jehan Dastoor
  • 647
  • 1
  • 8
  • 15
1
vote
1 answer

Find Centroid of Quadrilateral

Help me please with how to find Centroid of Quadrilateral? I have this constructor: public Quadrilateral(Point a, Point b, Point c, Point d) { if (a == null || b == null || c == null || d == null) { throw new…
Xa3uK
  • 21
  • 3
1
vote
2 answers

How to check if 4 points form a convex quadrilatera

I'm quite new to coding in general. I have found some answers for this question but the answers seem advanced for me. I'm trying to write my own Finite Element Project. For this I would like to write a method that checks if random 4 nodes given as…
plebianguy
  • 11
  • 1
1
vote
1 answer

How can I get a more regular surface quadmesh using gmsh?

I want to be able to generate a quadrilateral surface mesh that is highly regular (each face has, as far as possible, the same area) and aligned with the surface boundary. The following test .geo file simplifies the type of intended use case: lc =…
fink-nottle
  • 221
  • 2
  • 6
1
vote
1 answer

Given 4 vertices representing a quadrilateral, how can I divide it into N parts?

I am attempting to, given two dimensions (width and height) which represent a quadrilateral, partition that quad in to N parts where each part is as proportionally similar to the other as possible. For example, imagine a sheet of paper. It consists…
pookie
  • 3,796
  • 6
  • 49
  • 105
0
votes
0 answers

How calculate Transformation matrix for quadrilateral into a rectangle?

in the project I am taking a video of a rectangular page, four points are marked on that page, whose coordinates are known both in terms of pixels in the video (that is, their coordinates in the image) and their actual coordinates. I came across the…
zanyar
  • 1
  • 3
0
votes
0 answers

Find quadrilateral bounding box for detected object

I have been working on a Door detector in an uncontrolled environment. I used mask rcnn with to get the mask and bounding boxes. Though the class accuracy is very good, the mask is not very accurate. Also the expected result is a bounding…
DD02
  • 11
  • 4
0
votes
1 answer

Bilinear interpolation on quadrilateral

I am interpolating data from the vertices of a quadrilateral to any random point inside the quadrilateral. I implement this by first doing a coordinate transformation which reshapes the quadrilateral to a unit square and then using bilinear…
boltz
  • 63
  • 1
  • 7
0
votes
1 answer

How to determine if Quadrilateral is convex or not by given points

Is there any way to determine whether quadrilateral is convex or not? (meaning each of its angles are less than 180 degree) by using points. For example A(0,0) B(2,0) C(2,2) D(-1,3). How can we determine that all of the angles in ABCD quadrilateral…
givexa
  • 109
  • 2
  • 10
0
votes
2 answers

Java swing how to draw an image as a quadrilateral by using 4 points

I want to draw an image as a quadrilateral by using the points of the 4 corners as parameters. Does Java have anything already built in for that? I've seen a similar post but the solution given did not seem to do what I want. The function call would…
Frédéric Bélanger
  • 51
  • 5
0
votes
1 answer

Catmull Clarke doesn't preserve planar normals

In the toy example I show, one of the surface normals is clearly incorrectly pointing inwards. I can create a new cube with the normals outward facing as expected, but after processing with Catmull Clarke, there is no guarantee that all normals…
user1971339
  • 27
  • 6
0
votes
0 answers

To know if a quadrilateral intersects another one

I'm looking for an algorithm that allows me to know if a quadrilateral intersects another one. I'm not interested in the intersection itself, I just want to know if it exists. I have found solutions like the one proposed here:…
Jhon Snow
  • 67
  • 1
  • 6