How can I draw separating lines between colors in a 3D volume plot?

I am visualizing a 3D scalar function using the patch command and a given colormap (hsv) associated with the scalar values of the function. Unfortunately, Matlab dow not separate colors with lines, a feature which can be very useful to distinguish close values with similar colors. How can I draw lines between colors in my 3D patch plot? Many thanks for your help,

Luca

[KSSV]

A pictorial example will help us to help you.

[luca pavarino]

Here is a pictorial example of the map I get with the Matlab patch() command.

It shows the isochronal lines of cardiac activation times on part of the heart surface. The times (colors) range from 0 (red) to 120 msec (blue), in 10 msec steps. Some colors are readable, but other not (for example the green/blue regions). People in this field (computational cardiology) usually draw lines between colors, i.e. they mark the boundary of each color band with a black or white line. I searched the Matlab documentation to find how to add these separation lines between colors, but I could not find a solution. Could you please tell me how to do this?

Many thanks,

Luca

[G A]

Try to use options like this: 'EdgeColor','red','LineWidth,2

[luca pavarino]

I tried 'EdgeColor','red','LineWidth',2 inside the patch command but I get all the edges of the triangulation colored red. I need to put a line only at the boundary of each color (for example between light and dark green), not at the triangulation edges. Thanks,

Luca

[darova]

Can you please attach your data?

[luca pavarino]

The Matlab code fragment is the following and the data file is attached.

Thanks,

Luca

LV_S3_LAT; %load the data
V = Vertices(:,2:4);
T = Triangles(:,2:4)+1;
sV = size(V,1);
sT = size(T,1);
LAT = Values(:,4);
LAT_LV = LAT - min(LAT);
hh=patch('Faces',T,'Vertices',V,'FaceVertexCData',LAT_LV,'FaceColor','interp','EdgeColor','interp');
colormap(hsv);
colorbar;
grid on
view(115,-16);
set(gca,'Color','k');
shading interp
lightangle(-15,0)
hh.FaceLighting = 'gouraud';
hh.AmbientStrength = 0.3;
hh.DiffuseStrength = 0.8;
hh.SpecularStrength = 0.9;
hh.SpecularExponent = 25;
hh.BackFaceLighting = 'unlit';

Answer 1

[KSSV]

Remove the shading interp line after plotting.

LV_S3_LAT; %load the data
V = Vertices(:,2:4);
T = Triangles(:,2:4)+1;
sV = size(V,1);
sT = size(T,1);
LAT = Values(:,4);
LAT_LV = LAT - min(LAT);
hh=patch('Faces',T,'Vertices',V,'FaceVertexCData',LAT_LV,'FaceColor','interp','EdgeColor','interp','EdgeColor','k');
colormap(hsv);
colorbar;
grid on
view(115,-16);
set(gca,'Color','k');
% shading interp
lightangle(-15,0)
hh.FaceLighting = 'gouraud';
hh.AmbientStrength = 0.3;
hh.DiffuseStrength = 0.8;
hh.SpecularStrength = 0.9;
hh.SpecularExponent = 25;
hh.BackFaceLighting = 'unlit';

[darova]

"I need to put a line only at the boundary of each color (for example between light and dark green), not at the triangulation edges. Thanks,"

Luca

How can we find groups of colored triangles?

[KSSV]

That case, you need to plot the contours on the data. Use this file exchange:

https://in.mathworks.com/matlabcentral/fileexchange/38858-contour-plot-for-scattered-data

[luca pavarino]

These solutions do not work:

a) removing shading interp line after plotting just draw the triangles boundary, which is not what I need (I need to draw the boundary between the colors assigned by the colormap, i.e. I need to draw the isochronal lines or a scala field over a 3D volume).

b) the TRICONTOUR(TRI,X,Y,Z) function is not what I need because it draws countour lines of Z. What I need would be a TRICONTOUR(TRI,X,Y,Z,W) where W is a scalar function defined over the 3D volume described by X, Y, Z, but such a functions does not seem to exist in Matlab.

Luca