File Exchange

image thumbnail

subtri(F,V,n,unique​Opt)

version 1.3.0.0 (7.25 KB) by Kevin Moerman
Sub-triangulates patch format data. Can be used to increase the density of triangulated data

2 Downloads

Updated 28 Apr 2015

View License

[Fs,Vs]=subtri(F,V,n,uniqueOpt);
Sub-triangulates the triangles defined by the patch format data F (faces) and V (vertices). Can be used to increase the density of triangulated data.

Sub-triangulates the triangles defined by the patch format data F (faces) and V (vertices). Creates n addition points on the edges of the initial triangles, thus it creates (n+1).^2 triangles per original triangle. Two methods are implemented one which iteratively splits edges and can thus only be used if log2(n+1) is a positive integer. This method guarantees that all points are unique. If log2(n+1) is not a positive integer points are seeded on all edges initially creating non-unique points. However if uniqueOpt is 1 (default if not provided) these points are suppressed using the unique command (based on rounding of coordinates to 5th decimal place after edge length based scaling).

%% EXAMPLE
[X,Y] = meshgrid(linspace(-10,10,15));
Z = sinc(sqrt((X/pi).^2+(Y/pi).^2));
F = delaunay(X,Y); V=[X(:) Y(:) Z(:)]; C=mean(Z(F),2);

n=2;
[Fs,Vs]=subtri(F,V,n);
Vs(:,3)=sinc(sqrt((Vs(:,1)/pi).^2+(Vs(:,2)/pi).^2)); Z=Vs(:,3);Cs=mean(Z(Fs),2);

figure('units','normalized','Position',[0 0 1 1],'Color','w'); colordef('white');
subplot(1,2,1);patch('Faces',F,'Vertices',V,'FaceColor','flat','CData',C,'FaceAlpha',0.5,'EdgeColor','k','LineWidth',2); hold on;
axis tight; axis square; grid on; hold on; view(3); axis off;
title('Original','FontSize',20);
subplot(1,2,2);patch('Faces',Fs,'Vertices',Vs,'FaceColor','flat','CData',Cs,'FaceAlpha',0.5,'EdgeColor','k','LineWidth',0.5); hold on;
axis tight; axis square; grid on; hold on; view(3); axis off;
title(['n=',num2str(n)],'FontSize',20);

Cite As

Kevin Moerman (2020). subtri(F,V,n,uniqueOpt) (https://www.mathworks.com/matlabcentral/fileexchange/28277-subtri-f-v-n-uniqueopt), MATLAB Central File Exchange. Retrieved .

Comments and Ratings (6)

Oday Shahadh

It is interesting, but I need also to find the norm of each triangle, can you?

Lomas

Lomas

M P

Kevin Moerman

Updated 28/07/2010

Kevin Moerman

Will be updated shortly. Currently requires missing function and filtering of double points using "unique" is not reliable.

Updates

1.3.0.0

Updated with splitting method (faster)

1.2.0.0

Fixed normal direction and reference to missing function

1.1.0.0

Fixed instability due to "unique" function. Removed dependency on linspacen function which I did not upload.

MATLAB Release Compatibility
Created with R2015a
Compatible with any release
Platform Compatibility
Windows macOS Linux