%2019.10.21 suyunzzz
%将ply格式的点云数据，先转换为txt文件，
% 然后以mat格式读入并显示，然后将点云网格化。
%Q：为什么不直接从ply格式读取呢？
% A：因为matlab自带的点云工具箱貌似没有直接对ply或者pcd文件进行重构的。
% % % 所以得需要将ply文件转换为mat格式。
filename = './bunny/bunny/reconstruction/bun_zipper_res2.ply';
ptcloud = pcread(filename);
% pcshow(ptcloud);
Data(:,1)= double(ptcloud.Location(1:5:end,1)); %提取所有点的三维坐标
Data(:,2)= double(ptcloud.Location(1:5:end,2));
Data(:,3)= double(ptcloud.Location(1:5:end,3));
namesplit=strsplit(filename,'.ply'); %分割ply文件的名称，分成文件名与ply后缀名
frontname=namesplit{1}; %提取文件名，舍弃后缀名
% eval（'fid=fopen(''1_buny.txt'',''wt'');');
eval（['fid=fopen(''',frontname,'.txt'',''wt'');']);
[b1,b2]=size(Data);
for i=1:b1 %将二维数组Data写入txt格式文件中
for j=1:b2-1
fprintf(fid,'%.4f\t ',Data(i,j)); %所有坐标数据保留小数点后四位
end
fprintf(fid,'%.4f\n',Data(i,b2));
end
clear Data;
fclose(fid);
filename_read =[frontname,'.txt'];%将字符串拼接起来
fprintf('\n');
fprintf(filename_read);
fprintf('\n');
load(filename_read); %读入txt文件为mat文件
%将X1_buny赋值给一个p
p = bun_zipper_res2;
%显示点云
figure(1);
hold on
axis equal
title('点云','fontsize',14)
plot3(p(:,1),p(:,2),p(:,3),'r.')
view(-37.5,30)
[t]=MyCrust(p);
%% plot of the oyput triangulation
figure(2)
hold on
title('三角化输出','fontsize',14)
axis equal
% trisurf(t,p(:,1),p(:,2),p(:,3),'facecolor','g','edgecolor','r')%plot della superficie trattata
trimesh(t,p(:,1),p(:,2),p(:,3),'edgecolor','r')%plot della superficie trattata
view(-37.5,30)
MyCrust.m
%% MyCrust
%
%Simple surface recostruction program based on Crust algorithm
%Given a set of 3D points returns a triangulated tight surface.
%
%The more points there are the best the surface will be fitted,
%although you will have to wait more. For very large models an
%help memory errors may occurs.
%It is important even the point distribution, generally uniformly
% distributed points with denser zones in high curvature features
% give the best results.
%
%
% ͨ�����ڸ����������о��н��ܼ�����ľ��ȷֲ�����ṩ��ѽ����
% Remember crust algorithom needs a cloud representing a volume
% so open surface may give inaccurate results.
%
%
% If any problems occurs in execution, or if you found a bug,
% have a suggestion or question just contact me at:
%
% giaccariluigi@msn.com
%
%
%
%
%Here is a simple example:
%
%load Dino.mat%load input points from mat file
%
%[t]=MyCrust(p);
%
% figure(1)
% hold on
% title('Output Triangulation','fontsize',14)
% axis equal
% trisurf(t,p(:,1),p(:,2),p(:,3),'facecolor','c','edgecolor','b')
%
%Input:
% p is a Nx3 array containing the 3D set of points
%Output:
% t are points id contained in triangles Nx3 array too.
%
% See also qhull, voronoin, convhulln, delaunay, delaunay3, tetramesh.
%
%Author:Giaccari Luigi
%Last Update: 1/12/2008
%Creation: 10/10/2008
function [t]=MyCrust(p)
%% Main
starttime=clock;
%add points to the given ones, this is usefull
%to create outside tetraedrom
tic
p=AddShield(p);
fprintf('Addedded Shield: %4.4f s\n',toc)
tic
tetr=delaunayn(p);%creating tedraedron ����������
tetr=int32(tetr);%use integer to save memory
fprintf('Delaunay Triangulation Time: %4.4f s\n',toc)
%connectivity data
%find triangles to tetraedrom and tetraedrom to triangles connectivity data
tic
[t2tetr,tetr2t]=Connectivity(tetr);
fprintf('Connectivity Time: %4.4f s\n',toc)
tic
[cc,r]=CC();%Circumcenters of tetraedroms
fprintf('Circumcenters Time: %4.4f s\n',toc)
clear n
tic
t=Walking();%Flagging tetraedroms as inside or outside%�������忴���ǵ�����ⲿ��
fprintf('Walking Time: %4.4f s\n',toc)
time=etime(clock,starttime);
fprintf('Total Time: %4.4f s\n',time)
%% Circumcenters(Nested)
function [cc,r]=CC()
%finds circumcenters fro a set of tetraedrom
%points of tetraedrom
p1=(p(tetr(:,1),:));
p2=(p(tetr(:,2),:));
p3=(p(tetr(:,3),:));
p4=(p(tetr(:,4),:));
%vectors of tetraedrom edges
v21=p(tetr(:,1),:)-p(tetr(:,2),:);
v31=p(tetr(:,3),:)-p(tetr(:,1),:);
v41=p(tetr(:,4),:)-p(tetr(:,1),:);
%preallocation
cc=zeros(size(tetr,1),3);
%Solve the system using cramer method
d1=sum(v41.*(p1+p4)*.5,2);
d2=sum(v21.*(p1+p2)*.5,2);
d3=sum(v31.*(p1+p3)*.5,2);
det23=(v21(:,2).*v31(:,3))-(v21(:,3).*v31(:,2));
det13=(v21(:,3).*v31(:,1))-(v21(:,1).*v31(:,3));
det12=(v21(:,1).*v31(:,2))-(v21(:,2).*v31(:,1));
Det=v41(:,1).*det23+v41(:,2).*det13+v41(:,3).*det12;
detx=d1.*det23+...
v41(:,2).*(-(d2.*v31(:,3))+(v21(:,3).*d3))+...
v41(:,3).*((d2.*v31(:,2))-(v21(:,2).*d3));
dety=v41(:,1).*((d2.*v31(:,3))-(v21(:,3).*d3))+...
d1.*det13+...
v41(:,3).*((d3.*v21(:,1))-(v31(:,1).*d2));
detz=v41(:,1).*((v21(:,2).*d3)-(d2.*v31(:,2)))...
+v41(:,2).*(d2.*v31(:,1)-v21(:,1).*d3)...
+d1.*(det12);
%Circumcenters
cc(:,1)=detx./Det;
cc(:,2)=dety./Det;
cc(:,3)=detz./Det;
%Circumradius
r=((sum((p2-cc).^2,2))).^.5;%quadrato del raggio
end
%% Connectivity(Nested)
function [t2tetr,tetr2t]=Connectivity(tetr)
numt = size(tetr,1);
vect = 1:numt;
t = [tetr(:,[1,2,3]); tetr(:,[2,3,4]); tetr(:,[1,3,4]);tetr(:,[1,2,4])];%triangles not unique
[t,j,j] = unique(sort(t,2),'rows');%triangles
t2tetr = [j(vect), j(vect+numt), j(vect+2*numt),j(vect+3*numt)];%each tetraedrom has 3 triangles
% triang-to-tetr connectivity
nume = size(t,1);
tetr2t = zeros(nume,2,'int32');
count= ones(nume,1,'int8');
for k = 1:numt
for j=1:4
ce = t2tetr(k,j);
tetr2t(ce,count(ce)) = k;
count(ce)=count(ce)+1;
end
end
end % connectivity()
%% Walking(Nested)
function t=Walking()
np=size(p,1)-540;%540 = number of shield points put at the end of array
numtetr=size(tetr,1);
nt=size(tetr2t,1);
deleted=true(numtetr,1);%deleted tetraedroms
checked=false(numtetr,1);%checked tetraedros
onfront=false(nt,1);%tetraedroms that need to be checked
countchecked=0;
%First flag as outsde tetraedroms with Shield points
for i=1:numtetr
for j=1:4
if tetr(i,j)>np;
deleted(i)=true;
checked(i)=true;
onfront(t2tetr(i,:))=true;
countchecked=countchecked+1;
break
end
end
end
%tollerances to mark as in or out
toll=zeros(nt,1)+.95;
level=0;
alpha=zeros(nt,1);%intersection factor
%it is computed from radius of the tetraedroms circumscribed sphere
% and the distance between their center
for i=1:nt
if tetr2t(i,2)>0 %jump boundary tetraedrom
distcc=sum((cc(tetr2t(i,1),:)-cc(tetr2t(i,2),:)).^2,2);%distance from circumcenters
%intersection factor
alpha(i)=(-distcc+r(tetr2t(i,1))^2+r(tetr2t(i,2))^2)/(2*r(tetr2t(i,1))*r(tetr2t(i,2)));
end
end
clear cc
% Now we scan all tetraedroms. When one is scanned put on front is
% neighobur. This means that now even the neighobour can be
% checked. At the begining only tetraedroms with shield points are
% on front, because we are sure the are out.
% Tetraedrom with high intersction factor will be marked as equal
% else different.
% When I say high i mean under a set tollerance that becames lower as the algorithm
% progresses. This Aims to avoid errors propagation when a tetraedrom is wrong marked.
%
while countchecked<numtetr && level<50
level=level+1;%level of scan reached
for id=1:nt%loop trough triangles
if onfront(id)
tetr1=tetr2t(id,1);tetr2=tetr2t(id,2);%tetraedroms linked to triangle under analysis
if tetr2==0 %do not check boundary triangles
onfront(id)=false;
continue
elseif (checked(tetr1) && checked(tetr2)) %tetraedroms are already checked
onfront(id)=false;
continue
end
if alpha(id)>=toll(id) %flag as equal
if checked(tetr1)%find the checked one between the two
deleted(tetr2)=deleted(tetr1) ;%flag as equal
checked(tetr2)=true;%check
countchecked=countchecked+1;
onfront(t2tetr(tetr2,:))=true;%put on front all tetreadrom triangles
else
deleted(tetr1)=deleted(tetr2) ;%flag as equal
checked(tetr1)=true;%check
countchecked=countchecked+1;
onfront(t2tetr(tetr1,:))=true;%put on front all tetreadrom triangles
end
onfront(id)=false;%remove from front
elseif alpha(id)<-toll(id)%flag as different
if checked(tetr1)%find the checked one between the two
deleted(tetr2)=~(deleted(tetr1)) ;%flag as different
checked(tetr2)=true;%check
countchecked=countchecked+1;
onfront(t2tetr(tetr2,:))=true;%put on front all tetreadrom triangles
else
deleted(tetr1)=~(deleted(tetr2)) ;%flag as different
checked(tetr1)=true;%check
countchecked=countchecked+1;
onfront(t2tetr(tetr1,:))=true;%put on front all tetreadrom triangles
end
onfront(id)=false;%remove from front
else
toll(id)=toll(id)-.05;%tolleraces were too high next time will be lower
end
end
end
if level==31 %brute continuation(this may appens when the triangulation is corrupt)
warning('Brute continuation necessary')
onfront(t2tetr(~(checked),:))=true;%force onfront collocation
end
end
%delete tetraedroms marked as outside
tetr(deleted,:)=[];
%take boundary triangles from tetraedroms
%this is the raw surface and needs improvements to be used in CAD
%systems. Maybe in my next revision I will add surface post treatments.
%Anyway for grafical purpose this should be good.
%extract boundary triangles
t=BoundTriangles(tetr);
%Output Data
numchecked=countchecked/numtetr;
if level==50
warning([num2str(level),' th level was reached\n'])
else
fprintf('%4.4f th level was reached\n',level)
end
fprintf('%4.4f %% of Tetraedrom were checked\n',numchecked*100)
end
end
%% AddAddShield
function pnew=AddShield(p)
%find the bounding box
maxx=max(p(:,1));
maxy=max(p(:,2));
maxz=max(p(:,3));
minx=min(p(:,1));
miny=min(p(:,2));
minz=min(p(:,3));
%give offset to the bounding box
step=max(abs([maxx,minx,maxy,miny,maxz,minz]));
maxx=maxx+step;
maxy=maxy+step;
maxz=maxz+step;
minx=minx-step;
miny=miny-step;
minz=minz-step;
step=step/100;
N=10;
%creating a grid lying on the bounding box
vx=linspace(minx,maxx,N);
vy=linspace(miny,maxy,N);
vz=linspace(minz,maxz,N);
[x,y]=meshgrid(vx,vy);
facez1=[x(:),y(:),ones(N*N,1)*maxz];
facez2=[x(:),y(:),ones(N*N,1)*minz];
[x,y]=meshgrid(vy,vz-step);
facex1=[ones(N*N,1)*maxx,x(:),y(:)];
facex2=[ones(N*N,1)*minx,x(:),y(:)];
[x,y]=meshgrid(vx-step,vz);
facey1=[x(:),ones(N*N,1)*maxy,y(:)];
facey2=[x(:),ones(N*N,1)*miny,y(:)];
%add points to the p array
pnew=[p;
facex1;
facex2;
facey1;
facey2;
facez1;
facez2];
% figure(2)
% plot3(pnew(:,1),pnew(:,2),pnew(:,3),'.g')
end
%% BoundTriangles
function t=BoundTriangles(tetr)
numt = size(tetr,1);
vect = 1:numt;
t = [tetr(:,[1,2,3]); tetr(:,[2,3,4]); tetr(:,[1,3,4]);tetr(:,[1,2,4])];
[t,j,j] = unique(sort(t,2),'rows');
t2tetr = [j(vect), j(vect+numt), j(vect+2*numt),j(vect+3*numt)];
% triang-to-tetr connectivity
% Each row has two entries corresponding to the triangle numbers
% associated with each triangle. Boundary triangles have only one tetraedrom
nume = size(t,1);
tetr2t = zeros(nume,2,'int32');
count= ones(nume,1,'int32');
for k = 1:numt
for j=1:4
ce = t2tetr(k,j);
tetr2t(ce,count(ce)) = k;
count(ce)=count(ce)+1;
end
end
tbound=false(numt,1);
tbound=tetr2t(:,2)==0;
t=t(tbound,:);
end
