How to export 3D image from matlab and import it into maya

I have a 3D image in Matlab and I want to deform it using Maya,But I have no idea how I can 1)export it from Matlab and 2) how to import it into Maya.

Thanks alot!

Answer 1

[Anton Semechko]

Hi Ava,

I am assuming the image you are working with has already been segmented (or labelled) into distinct components. If so, here is what you can try:

Suppose the object of interest contained in your image is represented by voxels with values equal to 1, while the background is represented by values equal to -1.

1) First you may want to remove the voxelization (aka staircase) artefacts. You can do this by applying a low-pass filter to your image using the built-in MATLAB function titled ' smooth3'. Alternatively, you can implement your own pre-processing routine.

2) Extract the isosurface using marching cubes algorithm. For example, you can use the built-in function 'isosurface' or you can use the routine submitted by Peter Hammer: http://www.mathworks.com/matlabcentral/fileexchange/32506-marching-cubes

3) Export the mesh to a .stl file using the 'stlwrite' function that can be download from here: http://www.mathworks.com/matlabcentral/fileexchange/20922-stlwrite-write-binary-or-ascii-stl-file

Note that while using the above function, you may encounter the following error:

??? Undefined function or method 'narginchk' for input arguments of type 'double'.

Error in ==> stlwrite at 55
narginchk(2, inf)

To get rid of it you will have to edit out 'narginchk(2, inf)' on line 55

4) Finally, you can now import the .stl file into Maya and do what you have to ...

Here is an example:

% Simulate a segmented image
x=linspace(-1.1,1.1,50);
[x,y,z]=meshgrid(x);
F=(x.^4 + y.^4 + z.^4) - 10*(0.13)^2*(x.^2 + y.^2 + z.^2); % pill-box
F(F<=0)=-1;
F(F>0)=1;

figure('color','w'), isosurface(x,y,z,F,0), axis equal

% Smooth
F=smooth3(F);
figure('color','w'), isosurface(x,y,z,F,0)

% Extract the surface mesh
M=isosurface(x,y,z,F,0);
tr=TriRep(M.faces,M.vertices);

figure('color','w'), h=trimesh(tr); axis equal
set(h,'FaceColor','w','EdgeClor','b')

% Write to .stl
stlwrite('PillBoxExample.stl',tr.Triangulation,tr.X)

Good luck!

[ava]

Hello Anton,

So basically what I have right now is a surface(mesh) of the tongue and the following is the code to generate it,I believe there might be a simple way to convert it to obj format.

clear;

close all;

% the beat selection for the activation parameter (A1 ...A7) is -0.02.

A1=.006;%jaw height

A2=.006;%tongue tip

A3=-.02;%tongue dorsum

A4=.006;%tongue body

A5=-.02;%tongue low

A6=-.02;%tongue volume

A7=-.02;%tongue advance

%-----------------Reference mesh--------------------------------

vertices=[1 14.8863 25.5558 -102.576

2 9.69095 25.1874 -101.184

3 4.50876 24.6425 -99.7957

4 -0.682123 24.1926 -98.4048

5 -5.26158 21.8553 -97.1778

6 -7.65997 17.1568 -96.5351

7 -7.78844 11.7766 -96.5007

8 -6.91814 6.4643 -96.7339

9 -6.31057 1.1322 -96.8967

10 -6.59166 -0.6358 -96.8214

11 -8.35447 -5.4924 -96.349

12 -8.92437 -10.597 -96.1963

13 -7.42332 -15.5169 -96.5985

14 -4.41349 -19.6439 -97.405

15 -0.163421 -22.2464 -98.5438

16 4.73865 -23.3486 -99.8573

17 9.61851 -24.5577 -101.165

18 14.5134 -25.6949 -102.476

19 12.0579 17.6021 -97.4571

20 7.2214 21.4326 -96.686

21 2.67482 22.6482 -95.4677

22 -1.90077 22.0726 -94.2417

23 -5.65436 19.4149 -93.2359

24 -8.15321 15.3864 -92.5663

25 -9.53351 10.7034 -92.1965

26 -9.82039 5.7998 -92.1196

27 -9.32874 1.5036 -92.2514

28 -9.83488 -1.2325 -92.1157

29 -11.5967 -5.3727 -91.6437

30 -11.9396 -10.3259 -91.5518

31 -10.4782 -15.2409 -91.9434

32 -7.85667 -19.5707 -92.6458

33 -3.80075 -22.173 -93.7326

.

.

.

1229 2.42731 -60.1466 -59.0661];

tongue=[

273 272 37

37 272 19

272 273 303

303 304 334

37 19 20

37 20 38

38 20 21

38 21 39

39 21 22

.

.

.

461 444 445

];

figure;

node_xy = vertices(:,2:3)'; % X and Y coordinates

quad_node = tongue'; % Polygon nodes

value_xy = vertices(:,4)';% Z coordinates

node_num = size ( node_xy, 2 );%number of nodes

quad_num = size ( quad_node, 2 );% number of polygons

fprintf ( 1, '\n' );

fprintf ( 1, ' Number of nodes = %d\n', node_num );

fprintf ( 1, ' Number of quadrilaterals = %d\n', quad_num );

quad_surface_display ( node_num, node_xy, quad_num, quad_node, value_xy );

title('reference tongue');

%

% Terminate.

[Anton Semechko]

So what's your question?

[ava]

Hoe can I edit "narginchk(2, inf) " error?

Thanks

[Walter Roberson]

At the MATLAB command prompt, command

edit stlwrite.m

In the editor session, find line 55, the one with the narginchk. Add a % at the beginning of the line to comment it out. Save the file.

[ava]

Thank you very much ! that was a great solution

Answer 2

[Walter Roberson]

Perhaps using a .obj object would do? http://www.mathworks.com/matlabcentral/fileexchange/27982 My notes say that Maya can read and write those files; they also say: A description of Lightwave's .obj format can be found at http://www.martinreddy.net/gfx/3d/OBJ.spec

[ava]

Thanks.