Failed to load a mesh from gptoolbox. I am missing something, what is it?

Question

ehsan 2024-8-13

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2144879-failed-to-load-a-mesh-from-gptoolbox-i-am-missing-something-what-is-it

编辑： Walter Roberson 2024-8-13

% 1. Load a Mesh
[V, F] = readOFF('D:\Conferences and Workshops\SG Summer\MFC - S\codes\gptoolbox-master\gptoolbox-master\mesh.off');
% 2. Display the Mesh
figure;
trisurf(F, V(:,1), V(:,2), V(:,3), 'FaceColor', 'cyan', 'EdgeColor', 'none');
axis equal;
lighting gouraud;
camlight;
title('Original Mesh');
xlabel('X');
ylabel('Y');
zlabel('Z');
% Define the number of iterations and timestep for smoothing
num_iterations = 100;
time_step = 0.01;
% 3. Mean Curvature Flow (MCF) - Explicit Method
V_explicit = V; % Copy the vertices for the explicit method
for iter = 1:num_iterations
    % Compute the Laplace-Beltrami operator and mean curvature normal
    L = cotmatrix(V_explicit, F);
    HN = -L * V_explicit;
    
    % Update vertex positions
    V_explicit = V_explicit + time_step * HN;
end
% Display the smoothed mesh - Explicit Method
figure;
trisurf(F, V_explicit(:,1), V_explicit(:,2), V_explicit(:,3), 'FaceColor', 'cyan', 'EdgeColor', 'none');
axis equal;
lighting gouraud;
camlight;
title('MCF - Explicit Method');
xlabel('X');
ylabel('Y');
zlabel('Z');
% 3. Mean Curvature Flow (MCF) - Semi-Implicit Method
V_implicit = V; % Copy the vertices for the implicit method
for iter = 1:num_iterations
    % Compute the Laplace-Beltrami operator
    L = cotmatrix(V_implicit, F);
    
    % Solve (I - time_step * L) * V_new = V_old
    V_implicit = (speye(size(V_implicit, 1)) - time_step * L) \ V_implicit;
end
% Display the smoothed mesh - Semi-Implicit Method
figure;
trisurf(F, V_implicit(:,1), V_implicit(:,2), V_implicit(:,3), 'FaceColor', 'cyan', 'EdgeColor', 'none');
axis equal;
lighting gouraud;
camlight;
title('MCF - Semi-Implicit Method');
xlabel('X');
ylabel('Y');
zlabel('Z');

here is the link to loadmesh function: https://github.com/geometry-processing/gptoolbox/blob/master/mesh/load_mesh.m

and the readOFF: https://github.com/geometry-processing/gptoolbox/blob/master/mesh/readOFF.m

I get this error:

shittyday (%sorry this is the name of the script)
Error using fscanf
Invalid file identifier. Use fopen to generate a valid file identifier.
Error in readOFF (line 27)
  OFFheader = upper(fscanf( fp, '%s\n', 1 ));
Error in shittyday (line 2)
[V, F] = readOFF('D:\Conferences and Workshops\SG Summer\MFC - S\codes\gptoolbox-master\gptoolbox-master\mesh.off');
 

12 个评论
显示 10更早的评论隐藏 10更早的评论

ehsan 2024-8-13

在 MATLAB Online 中打开

Hello @Vinay It is here on this git: https://github.com/geometry-processing/gptoolbox/blob/master/mesh/readOFF.m

I will put it there too:

function [V,F,UV,C,N] = readOFF( filename )
  % READOFF reads an OFF file with vertex/face information
  %
  % [V,F,UV,C,N] = readOFF( filename )
  %
  % Input:
  %  filename  path to .off file
  % Outputs:
  %  V  #V by 3 list of vertices
  %  F  #F by 3 list of triangle indices
  %  UV  #V by 2 list of texture coordinates
  %  C  #V by 3 list of colors
  %  N  #V by 3 list of normals
  %
  % See also: load_mesh, readOBJfast, readOBJ
% (C) 2007 Denis Kovacs, NYU
%-------------------------------------------------------------------------
  V = [];
  F = [];
  UV = [];
  C = [];
  N = [];
  
  fp = fopen( filename, 'r' );
  OFFheader = upper(fscanf( fp, '%s\n', 1 ));
  if OFFheader(end-2:end) ~= 'OFF'
    warning('no OFF file!') 
    fclose(fp);
    return;
  end
  OFFdim = 3;
  OFF_N = 0; OFF_C=0; OFF_ST=0;
  
  if find(OFFheader=='N') OFFdim = OFFdim+3; OFF_N=1; end
  if find(OFFheader=='C') OFFdim = OFFdim+3; OFF_C=1; end
  if find(OFFheader=='S') OFFdim = OFFdim+2; OFF_ST=1; end
  % eat any comments before
  line = eat_comments(fp,'#');
  
  d = sscanf( line, '%d', 3);
  nV = d(1); nF = d(2); nE = d(3);
  
  %disp(sprintf('  - Reading %d vertices', nV));
  
  switch OFFdim
      case  3; OFFV = textscan( fp, '%f %f %f', nV);
      case  5; OFFV = textscan( fp, '%f %f %f %f %f', nV);
      case  6; OFFV = textscan( fp, '%f %f %f %f %f %f', nV);
      case  7; OFFV = textscan( fp, '%f %f %f %f %f %f %f', nV);
      case  8; OFFV = textscan( fp, '%f %f %f %f %f %f %f %f', nV);
      case  9; OFFV = textscan( fp, '%f %f %f %f %f %f %f %f %f', nV);
      case 10; OFFV = textscan( fp, '%f %f %f %f %f %f %f %f %f %f', nV);
      case 11; OFFV = textscan( fp, '%f %f %f %f %f %f %f %f %f %f %f', nV);
      otherwise; fclose(fp); error('Unsupported number of vertex entries');
  end
  
  try
     OFFV = cell2mat(OFFV); 
  end
  
  OFFdim = 1;
  V = OFFV(:,OFFdim:(OFFdim+2)); OFFdim = OFFdim + 3;
  if (OFF_N) N = OFFV(:,OFFdim:(OFFdim+2)); OFFdim = OFFdim + 3; end
  if (OFF_C) C = OFFV(:,OFFdim:(OFFdim+2)); OFFdim = OFFdim + 3; end
  if (OFF_ST) UV = OFFV(:,OFFdim:(OFFdim+1)); OFFdim = OFFdim + 2; end
  
  if (nF ~= 0)
    %disp(sprintf('  - Reading %d faces', nF));
    temp = textscan( fp, '%d %d %d %d %d %d %d %d %d %d %d', nF );
    sz = temp{1}(1);
    if all(sz == cell2mat(temp(1)))
      F = double (cell2mat( temp(2:sz+1 ))) +1;
    else
      warning('Trivially triangulating high degree facets');
      F = zeros(sum(temp{1}-2),3);
      fi = 1;
      for f = 1:size(temp{1},1)
        for j = 3:temp{1}(f);
          F(fi,:) = [temp{2}(f) temp{j}(f) temp{j+1}(f)]+1;
          fi = fi+1;
        end
      end
    end
  else
    F = [];
  end
  fclose(fp);
  
  %disp('  - done.');
end

am I loading the data correctly?

ehsan 2024-8-13

在 MATLAB Online 中打开

Aha! - I think the path is correct .. Here is the load_mesh.m

function [V,F] = load_mesh(filename,varargin)
  % read in vertices and faces from a .off or .obj file
  % 
  % [V,F] = load_mesh(filename)
  % [V,F] = load_mesh(filename,'ParameterName',ParameterValue, ...)
  %
  % Input:
  %   filename  file holding mesh
  %   Optional:
  %     'Quiet' followed by whether to be quiet {false}
  % Output:
  %   V (vertex list) 
  %   F (face list) fields
  %
  % Copyright 2011, Alec Jacobson (jacobson@inf.ethz.ch)
  %
  % See also: readOBJ, readOBJfast, readOFF
  %
  % parse any optional input
  v = 1;
  quiet = false;
  while(v <= numel(varargin))
    switch varargin{v}
    case 'Quiet'
      v = v+1;
      assert(v<=nargin);
      quiet = varargin{v};
      quiet = quiet * 1;
    otherwise
      error(['Unsupported parameter: ' varargin{v}]);
    end
    v = v + 1;
  end
  % if mex libigl reader exists use that (up to 25x faster for .obj)
  if exist('read_triangle_mesh','file')==3
    try
      [V,F] = read_triangle_mesh(GetFullPath(filename));
      if ~isempty(V) && ~isempty(F)
        return;
      end
      % else keep trying below
    catch e
      warning(e.message);
      % else keep trying below
    end
  end
  
  [~,~,ext] = fileparts(filename);
  ext = lower(ext);
  switch ext
  case '.3ds'
    [V,F] = read3DS(filename);
  case '.obj'
    try
      [V,F] = readOBJfast(filename);
    catch exception
      if ~quiet
        fprintf('Fast reader failed, retrying with more robust, slower reader\n');
      end
      [V,F] = readOBJ(filename);
    end
  case '.off'
    [V,F] = readOFF(filename);
  case '.ply'
    [V,F] = readPLY(filename);
  case '.stl'
    [V,F] = readSTL(filename);
  case '.wrl'
    [V,F] = readWRL(filename);
  case '.xml'
    [V,F] = read_mesh_from_xml(filename);
  otherwise
    error('Unknown mesh format: %s',ext);
  end
end

ehsan 2024-8-13

@VinayYour demo worked and gave this output

ehsan 2024-8-13

编辑：Walter Roberson 2024-8-13

@Vinay oh, I think there is not any filename.off in the gptoolbox package I downloaded. The package is on this git: https://github.com/geometry-processing/gptoolbox/tree/master

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