i want to export 3d stl format image into matlab and want to see in matlab

I am using the command

gm = importGeometry('Cute Dragon 2.stl');

pdegplot(gm);

but this is howing me only surface view and i need volume view.

Answer 1

[Star Strider]

The stlread function is another option.

Answer 2

[DGM]

I've used STL Tools from the FEX before.

% needed to zip attachments for the forum
unzip things.zip

% read the file
fname = 'things/heaterductmount.stl';
[V,F,N,~] = stlReadAscii(fname);

% plot it
patch('faces',F,'vertices',V, ...
    'facecolor',[1 1 1], ...
    'edgecolor','none');

% set up lighting, etc
shapelighting(gca)

Star Strider's suggestion works too. T is a triangulation object, so you'll handle it differently.

% read the file
fname = 'things/heaterductmount.stl';
T = stlread(fname);

% plot it
trisurf(T, ...
    'facecolor',[1 1 1], ...
    'edgecolor','none');

% set up lighting, etc
shapelighting(gca)

[Reet]

But this command shows my 3d stl image in white color over white surface. How i can make my image colorful.

[DGM]

Demonstrably, it shows a white part illuminated by two strategically placed lights of different color so as to reveal the surface contours over a broad range of viewing angles. I think most people would call that "colorful".

If you're doing something else, then you're doing something else. If you want something else specific, then you'll have to say what you want. If you're trying to do the same thing as the example, but getting errors, what are the errors? The function I used for the lighting setup is attached above.

If you don't want to use lighting to reveal the surface, then how do you want to show it? Any solid color will tend to have terrible contrast.

% needed to zip attachments for the forum
unzip things.zip

% read the file
fname = 'things/heaterductmount.stl';
T = stlread(fname);

% if you don't want white, then pick a color
trisurf(T, ...
    'facecolor','m', ...
    'edgecolor','none');

% you'll still have to do figure setup somehow
material('shiny') % without lighting, this won't matter
axis('image')
view(3)
grid('on')

You could try to highlight edges, but most realistic models will end up having so many edges that it will just look like a complete mess. Is it even important to show the edges?

figure
% or maybe you want to draw all the edges?
trisurf(T, ...
    'facecolor','m', ...
    'edgecolor','k');

% you'll still have to do figure setup somehow
material('shiny') % still won't matter
axis('image')
view(3)
grid('on')

In order to reveal the surface contours, you'll need some sort of lighting. While this might look great from one angle, rotating the camera will reveal that the bottom of the part is completely unviewable because it's in shadow. Lights are stationary in the xyz space. Using camlight() only creates the light with an initial position relative to the current camera position. It's possible to make the light track the camera position as it moves, but it would take considerable setup.

figure
% if you don't want white, then pick a color
trisurf(T, ...
    'facecolor','m', ...
    'edgecolor','none');

% you'll still have to do figure setup somehow
camlight % add lighting this time
material('shiny')
axis('image')
view(3)
grid('on')

If the goal is to color the faces differently, then you'll have to come up with a way to describe how the faces should be colored.

[DGM]

FWIW, here's an example based on the linked thread:

% needed to zip attachments for the forum
unzip things.zip

% read the file
fname = 'things/heaterductmount.stl';
T = stlread(fname);

% if you don't want white, then pick a color
h = trisurf(T, ...
    'facecolor','m', ...
    'edgecolor','none');

% set up the axes with one offset light that follows the camera
followerlight(h);

% this does all the figure setup
function followerlight(hobj)
    set(hobj,'HitTest','off'); % same as in Matt's example
    hax = ancestor(hobj,'axes'); % get the parent axes
    set(hax,'NextPlot','add'); % same as in Matt's example
    set(hax,'buttondownfcn', @buttondownfcn); % same as in Matt's example
    
    material(hax,'shiny') % or whatever reflectance you prefer
    axis(hax,'image')
    view(hax,3)
    grid(hax,'on')
    
    c = camlight('headlight');              % add light
    set(c,'style','infinite');              % set style of light

    function buttondownfcn(ax,~)
        fig = ancestor(ax,'figure');        % get figure handle
        [oaz, oel] = view(ax);              % get current azimuth and elevation
        oloc = get(0,'PointerLocation');    % get starting point
        set(fig,'windowbuttonmotionfcn',{@rotationcallback,ax,oloc,oaz,oel});
        set(fig,'windowbuttonupfcn',{@donecallback});
    end

    function rotationcallback(~,~,ax,oloc,oaz,oel)
        locend = get(0, 'PointerLocation'); % get mouse location
        dx = locend(1) - oloc(1);           % calculate difference x
        dy = locend(2) - oloc(2);           % calculate difference y
        factor = 2;                         % correction mouse -> rotation
        newaz = oaz-dx/factor;              % calculate new azimuth
        newel = oel-dy/factor;              % calculate new elevation
        view(ax,newaz,newel);               % adjust view
        c = camlight(c,'headlight');        % adjust light
    end

    function donecallback(src,~)
        fig = ancestor(src,'figure');           % get figure handle
        set(fig,'windowbuttonmotionfcn',[]);    % unassign windowbuttonmotionfcn
        set(fig,'windowbuttonupfcn',[]);        % unassign windowbuttonupfcn
    end

end

Obviously, I can't demonstrate the behavior in the browser.

[Reet]

Thank you so much sir for your valuable reply. Actually i want to encrypt a 3d image in stl format .For this, i have to import the image in matlab with original colors. when i am using % read the file

fname = 'things/heaterductmount.stl';

T = stlread(fname);

% plot it

trisurf(T, ...

'facecolor',[1 1 1], ...

'edgecolor','none');

% set up lighting, etc

shapelighting(gca)

matlab is showing "Unrecognized function or variable 'shapelighting'." Can you please provide me help regarding this to import the original colors of 3d image.

[DGM]

The function is attached in the answer above. The only thing it does is set up the axes and lights. The object color is set in the call to patch() or trisurf(). The reason I used white is so that the lighting color isn't influenced.

A normal STL file has no color information. It's just geometry information. Apparently it's possible to cram color info into an STL file, but I don't know that either of the STL tools mentioned above will read it. I don't have an example of such a file, so I can't really test to see if any stored color info could be read or how it could be applied.

[Reet]

Can you please recommend me which format of 3d image is suitable for encryption process ?

[DGM]

I am not intimately familiar with all the various file formats, the degree to which the features of each one are supported within MATLAB, and I have no idea what your requirements are. From what I can tell, it's not clear why the format should have any bearing on whether the file can be encrypted. It's also not clear to me what sort of color information is expected, or whether it's necessary.

[Reet]

okk, thank you so much sir for your help.