Problem using minboundquad function to create a minimum bounding quadrilateral for a given pointset

2021 5 18
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更新时间：2021 5 26
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I had modified one line in the minboundquad.m function to remove the collinear edges in the pointset.
from
edges = convhull(x,y);
to
edges = convhull(x,y,'Simplify',true);
The main code is
load points2.txt
x = points2(:,1);
y = points2(:,2);
[qx,qy] = minboundquad(x,y)
Result I got is below.
This is the output
There is some error I could not find out. Can someone help me solve this?

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Gowtham HariHara
Gowtham HariHara 2021-5-26

0 个投票

Modifying the line in minboundquad.m from
if ( A_i < quadarea)
to
if (( A_i < quadarea)&& all(abs([qxi qyi]) < 1e15))
resolves the issue.
Thanks to @Michael Sapper for this suggestion(found in comment section of this toolbox)

更多回答（1 个）

0 个投票

Hi,
I did not seem to find any error while reproducing and I got the below result after changing minboundquad.m
from
edges = convhull(x,y);
to
edges = convhull(x,y,'Simplify',true);
I got the Warning: Matrix is close to singular or badly scaled. Results may be inaccurate.
Can You explain what your error was?

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Gowtham HariHara
Gowtham HariHara 2021-5-26
编辑：Gowtham HariHara 2021-5-26
@Shiva Kalyan Diwakaruni Thank you for your time.
There is no quadrilateral formed. Outcome of this function should be four vertices of a quadrilateral.
Gowtham HariHara
Gowtham HariHara 2021-5-26
@Shiva Kalyan Diwakaruni Do you want to see the expected outcome of this function ?
This function worked for one of the less complex pointset. If you would like to see the result for a working pointset, I can show a screenshot.

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