Find holes and gaps in .stl files
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Eduardo
am 2 Feb. 2012
Kommentiert: mahmoud elmesery
am 24 Mai 2021
Hi,
I need to find gaps and holes in a stl file. I don´t know if there´s a function developed that can help me. I started to work with MATLAB recently and i´m finding some dificulties. I found 2 ways of doing this, each triangle should have 3 adjacent triangles or each edge must have 2 triangles in common. Hope someone could give a hand. Thank´s.
Eduardo G.
3 Kommentare
agdfg sdgfdg
am 10 Dez. 2013
[unqEdges, ~, edgeNos] = unique(edges,'rows'); | Error: Expression or statement is incorrect--possibly unbalanced (, {, or [. this the error i observed.
And i request you to suggest some other algorithms or codes for STL File Correction.
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Sven
am 3 Feb. 2012
Hi Eduardo,
Firstly you need to read the .stl file in as faces and vertices. I'll presume you've already got that done (as Anton points out, stlread is available here http://www.mathworks.com/matlabcentral/fileexchange/22409-stl-file-reader).
Next, as you wrote: each edge must have 2 triangles in common... I think this is a good start. Here's some code that will make a test faces/vertices mesh, then determine such a thing:
% MAKE a face/vertices structure
tmpvol = zeros(20,20,20); % Empty voxel volume
tmpvol(8:12,8:12,5:15) = 1; % Turn some voxels on
fv = isosurface(tmpvol, 0.99);
% REMOVE a face
fv.faces(30,:) = []; % Remove a face!
% TEST for gaps or holes
edges = sort(cat(1, fv.faces(:,1:2), fv.faces(:,2:3), fv.faces(:,[3 1])),2);
[unqEdges, ~, edgeNos] = unique(edges,'rows');
if size(edges,1) == size(unqEdges,1)*2
% Every edge is used twice... consistent with a closed manifold mesh
disp('No problem!')
else
badEdgesMask = hist(edgeNos, 1:max(edgeNos))~=2;
badEdgeNos = edgeNos(badEdgesMask);
badNodeNos = edges(badEdgeNos,:);
badFaceNos = find(sum(ismember(fv.faces, badNodeNos),2)>=2);
end
Does this answer the question for you?
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Eduardo
am 26 Feb. 2012
2 Kommentare
Sven
am 29 Feb. 2012
If you mean that the variable badEdgesMask only contains ones and zeros, then you need to realise that it's using logical indexing... if you're sure there's a problem, make a small example (such as the one I made) and show how it's not working.
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