Discussion Forum

I'm surprised to see COMSOL can handle such "geometry". It's really amazing... considering there are so many details, which more look like noise.

Curious to know more about it.
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Pu, ZHANG
DTU Fotonik

I'm surprised to see COMSOL can handle such "geometry". It's really amazing... considering there are so many details, which more look like noise.

Curious to know more about it.
--
Pu, ZHANG
DTU Fotonik

yes, you are right. there are too much details. this is just my first try. when I really do serious calculations later, which would be also quite simple, I should think about getting the boundary smoother.

Chunyan

If those details don't make much difference in the physics, I think removing them will make the calculation smoother.

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Pu, ZHANG
DTU Fotonik

Hi,

I am having similar problems with select 2D images that I am trying to convert into geometries that are subsequently imported into COMSOL. By and large, most images that I am processing work fine, but every once in a while there are some that give the error message below. I am not sure the problem is related to the complexity of the image, given that they are all quite similar, and a VERY different data set I am using that is significantly more complicated has the same issues, although with greater frequency. I tried to upload a good image and a bad one for example, but the forum does not seem to allow attachments at this time. If anyone knows what the problem could be I would greatly appreciate some help with this closed source mphimage2geom function.

Attempted to access f(1); index out of bounds because numel(f)=0.

Error in mphimage2geom>creategeom (line 513)

Error in mphimage2geom (line 128)

HI. Your problem may be resulted from 3 aspect:

1) The image which is not able to be input is not a square matrix (not NxN)
2) Your image may be 3 dimensional matrix ,which means the image is colorful.
you can use matlab code to transfer to 2 dimensions.

if ndims(I)==3
I=rgb2gray(I)
end
Where I is imread (...)
3) if your pixel matrix is a square matrix, your problem may be that your current geometric is occupying your Comsol Multiphysics. Save your current geometry and create a new model so that you can input your second image

Hopefully it is helpful to you

Regard CHI

Hi Chi Chen,

Thanks for you suggestions, but none of the three options you describe are the case we are facing here. At best, the third option would be the most plausible, but uploading the geometry to COMSOL was not even possible because generating a geometry in the matlab interface is what is not working. It appears that watershedding the porous medium we are using for simulations fixes the problem most of the time, though it would be good to know why this type of data manipulation is required.

Thanks,

Veronica

Hi,

I got same error with my optical fiber geometries.
I have noticed that the problem appears when an object touching perimeter of image
has some holes inside.

Karol Tarnowski

Actually, I have got the detial steps for importing your image (SEM) into COMSOL, no matter how complex your image is. You can use "ImageJ; AI-CS4; Auto-CAD " for preprocessing your image separately. And the geometric modeling can be edited under your "Geometry" unit in your COMSOL software.