Problem 45230. Remove duplicated triangles

Created by Nicolas Douillet

Solve Later

{"relationships":[{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/document","targetMode":"","relationshipId":"rId1","target":"/matlab/document.xml"},{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/output","targetMode":"","relationshipId":"rId2","target":"/matlab/output.xml"}],"parts":[{"partUri":"/matlab/document.xml","relationship":[],"contentType":"application/vnd.mathworks.matlab.code.document+xml","content":"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<w:document xmlns:w=\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\"><w:body><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Input T is a triangulation (triplet list of indices -positive integers-, each index refering to a vertex number in a corresponding vertices list).</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>It sometimes happens a triangle may be duplicated several times. The goal of this problem is to remove all the duplicated triangles of T, and to keep only one.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>For instance if :</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[T_in = [1 2 3;...\n 4 5 6;...\n 1 2 3;...\n 7 8 9;...\n 6 4 5;...\n 10 11 12;...\n 2 1 3;...\n 8 7 9;...\n 10 11 12]]]></w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>then the output must be :</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[T_out = [1 2 3;...\n 4 5 6;...\n 7 8 9;...\n 10 11 12]]]></w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>since rows [1 2 3], [6 4 5], [2 1 3], [8 7 9], and [10 11 12] are just duplicata. Indeed triangle [i2 i1 i3] is the same as triangle [i1 i2 i3] for example.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Hypothesis :</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"ListParagraph\"/><w:numPr><w:numId w:val=\"1\"/></w:numPr></w:pPr><w:r><w:rPr><w:b/></w:rPr><w:t>T is always a N x 3 integer matrix with N &gt; 0 (non empty matrix)</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"ListParagraph\"/><w:numPr><w:numId w:val=\"1\"/></w:numPr></w:pPr><w:r><w:t>Each row / triangle of T always contains three distinct integers</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Good work Matlab bro ! :)</w:t></w:r></w:p></w:body></w:document>"},{"partUri":"/matlab/output.xml","contentType":"text/xml","content":"<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\" ?><embeddedOutputs><metaData><evaluationState>manual</evaluationState><layoutState>code</layoutState><outputStatus>ready</outputStatus></metaData><outputArray type=\"array\"/><regionArray type=\"array\"/></embeddedOutputs>"}]}

Input T is a triangulation (triplet list of indices -positive integers-, each index refering to a vertex number in a corresponding vertices list).It sometimes happens a triangle may be duplicated several times. The goal of this problem is to remove all the duplicated triangles of T, and to keep only one.For instance if :<pre class="language-matlab">T_in = [1 2 3;...
 4 5 6;...
 1 2 3;...
 7 8 9;...
 6 4 5;...
 10 11 12;...
 2 1 3;...
 8 7 9;...
 10 11 12]
</pre>then the output must be :<pre class="language-matlab">T_out = [1 2 3;...
 4 5 6;...
 7 8 9;...
 10 11 12]
</pre>since rows [1 2 3], [6 4 5], [2 1 3], [8 7 9], and [10 11 12] are just duplicata. Indeed triangle [i2 i1 i3] is the same as triangle [i1 i2 i3] for example.Hypothesis :<ul><li>T is always a N x 3 integer matrix with N &gt; 0 (non empty matrix)</li><li>Each row / triangle of T always contains three distinct integers</li></ul>Good work Matlab bro ! :)

Solve

Solution Stats

15 Solutions
10 Solvers

Last Solution submitted on Oct 14, 2020

Last 200 Solutions

Problem Comments

Problem Recent Solvers10

Problem Tags

3d duplicat edge find geometry index indices mathematics mesh mesh processing surface triangle triangulation trimesh triplet vertex vertices

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Problem 45230. Remove duplicated triangles

Solution Stats

Last 200 Solutions

Problem Comments

Problem Recent Solvers10

Suggested Problems

More from this Author9

Problem Tags

Community Treasure Hunt

Problem 45230. Remove duplicated triangles

Solution Stats

Last 200 Solutions

Problem Comments

Problem Recent Solvers10

Suggested Problems

More from this Author9

Problem Tags

Community Treasure Hunt

Players