How can I analyze stl files and then redraw them in matlab? I need to write some code

Hello

I need help and guidance.

This is the goal. I need to write code in matlab to analyze some stl pictures and then redraw it in matlab. I could also use solidworks too, but I don't have a lot of experience in solidworks. Anything helps Thanks

Answer 1

[KSSV]

YOu can read .stl files using this function: https://in.mathworks.com/matlabcentral/fileexchange/22409-stl-file-reader?focused=5193625&tab=function

[JoshT_student]

Thank you, but I need more than that. I need some idea how to write code. I now have my data points from the curve fitting app. I just don't know how to use code to make the SEM image again. I attached my data points.

Answer 2

[DGM]

For context:

https://www.mathworks.com/matlabcentral/answers/405855-how-do-i-redraw-a-picture-given-to-me-using-its-data-points-that-i-ve-found-using-the-curve-fitting

I have no idea where this was going, but here's an implausible interpretation of "STL from pseudobinary image":

unzip stuff.zip % for the forum

% an antialiased RGB image
inpict = imread('SEM.png');

% get rid of extraneous channels
inpict = im2gray(inpict);

% binarize it and get the blob boundaries
mk = imbinarize(inpict);
[Vc,~,nblobs] = bwboundaries(mk);

% show boundary curves atop the mask
imshow(mk); hold on
for k = 1:nblobs
    plot(Vc{k}(:,2),Vc{k}(:,1),'linewidth',2)
end

% flip a bunch of stuff
for k = 1:nblobs
    % the source is an image, so we probably want to invert Y
    Vc{k}(:,1) = size(inpict,1) - Vc{k}(:,1) + 1;
    
    % flipping Y means we need to flip the boundary direction
    % also need to remove duplicate vertex on closure
    % B is [y x]; we need that flipped too
    Vc{k} = Vc{k}(end-1:-1:1,[2 1]);
end

% consolidate the vertex list
V = cell2mat(Vc);

% construct the edge lists in the same direction
% the vertex lists in Vc don't need to be the same length
sz = cellfun(@(x) size(x,1),Vc); % length of each vertex list
szc = [0; cumsum(sz)];
E = zeros(0,2);
for k = 1:numel(Vc)
    v = 1+szc(k):szc(k+1);
    thisE = [v; circshift(v,-1)].';
    E = [E; thisE];
end

% TRIANGULATION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% do a constrained triangulation to generate the triangles
T = delaunayTriangulation(V(:,1:2),E);

Warning: Duplicate data points have been detected and removed.
The Triangulation indices and constraints are defined with respect to the unique set of points in delaunayTriangulation.

F = T.ConnectivityList(isInterior(T),:);
V = T.Points;

% or better yet, use mesh2D (FEX #25555)
%[V,~,F,~] = refine2(V,E);

% clean up leftover points
[F V] = pruneunusedverts(F,V);

% display it using patch()
figure
patch('faces',F,'vertices',V, ...
    'facecolor','w','edgecolor','k');
axis equal; grid on
xlabel('X'); ylabel('Y')

% EXTRUSION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% extrude the part into 3D
[F V] = extrude(F,V,50); % pick a thickness

% write to file
stlwrite(triangulation(F,V),'testfile.stl')

% display it using patch()
figure
patch('faces',F,'vertices',V, ...
    'facecolor','w','edgecolor','none');
view(3); camlight; view(10,33)
axis equal; grid on
xlabel('X'); ylabel('Y'); zlabel('Z')

●

For other interpretations, see also:

Generate a lofted relief from a 2D depthmap image

https://www.mathworks.com/matlabcentral/answers/1926360-plotting-3d-surface-using-depth-map-and-grey-scale-image#comment_3031456

Similar lofting or dithering for a lithophane

https://www.mathworks.com/matlabcentral/answers/2104036-generate-3d-model-from-a-2d-image

Yeah, but how would i do the lofting in 2012???

https://www.mathworks.com/matlabcentral/answers/54069-how-can-i-turn-a-grayscale-image-into-a-stl-3d-file

Extruding a logical image

https://www.mathworks.com/matlabcentral/answers/254154-how-can-i-produce-a-stl-file-from-a-2d-image