One specific geometry with different resolutions.

[Arash Imani Aria]

Hi,

I use DREAM3D to create geometry files for DAMASK and Abaqus. I need to generate a cube with 30 grains and with different resolutions (16x16x16 or 32x32x32 etc.). But, when using DREAM3D, changing resolution results in different number of grains. How can I have a fixed geometry, with various resolutions?

Thanks in advance,

Arash

[Michael Jackson]

Dear Arash,

     Each time the Synthetic generation pipeline runs, essentially all the filters past the “Initialize Synthetic Volume” DREAM3D will regenerate all of the grains based on values sampled from the distributions. This will give you a different microstructure each time through the pipeline. My suggestion would be the following.

 

Create a microstructure with a very fine spacing/resolution value. For instance, in the “Initialize Synthetic Volume” filter you might start with dimensions of 256x256x256 and a resolution of 0.1 x 0.1 x 0.1.

 

Near the end of the pipeline you can then add the “Change Resolution” filter. Double the resolution from the original values (0.2 x 0.2 x 0.2 in this example), check the renumber features, and check the “Save as New Data Container”. Fill in the rest of the input values to match yours. This will resample the original microstructure to a “lower resolution”. Note that if you have small grains, they may get “swallowed up” or “skipped over” based on your new resolution values. If you want additional resolutions, just insert the “Change Resolution” filter as many times as you want new resolutions. Keep in mind that you should ALWAYS pick the original resolution microstructure as most of the time it is beneficial to start with the highest detail model.

 

I am including an example pipeline to help get you started.

 

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Mike Jackson

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[Arash Imani Aria]

Dear Mike,

Many thanks for your thorough answer.

In the "Initialize Synthetic Volume" filter, I started a microstructure with dimensions of 256x256x256 and a resolution of 0.1 x 0.1 x 0.1. Then I use "change spacing" twice. Once with a 0.2 x 0.2 x 0.2 spacing and once with 0.4 x 0.4 x 0.4. And each time I request two types of outputs using "VTK rectilinear grid exporter" and "DAMASK exporter". I need the VTK files to visualize in Paraview and DAMASK files to run simulations on the created geometries. 

By checking the "material.config" files, which are exported for DAMASK, I assume that the operation was successful. Because the "material.config" files start with the same Euler angles for both cases. But, I also need to visualize the difference of these two resolutions. I tried to do this with "VTK rectilinear grid exporter", but I cannot see the difference. I think the reason is that the VTK file is created based on the "Dimensions",  which in this case is 256 x 256 x 256.

I attach my pipeline. 

[Michael Jackson]

Add the “Write DREAM.3D File” to the end of the pipeline. This will produce a pair of  files. Use the one with the .xdmf extension to load into ParaView. https://www.youtube.com/watch?v=j7WtJOcK1VI go to 7:10 time stamp in the video to see how to load the data in ParaView.

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[Arash Imani Aria]

Dear Mike,

It has been a while since I asked this question and I remember that I successfuly generated my desired geometry at the time. 

But now that I am back to the topic again, I am unable to generate two different resolutions for a unique geometry. My logic is to have 256x256x256 dimensions with 0.1 at  “Initialize Synthetic Volume”, then Export DAMASK files. After that, use "change resolution", and alter the resolution from 0.1 to 0.2, and then Export DAMASK files. But, as I do it, I get the same files for both cases, which is a grid with 256x256x256 resolution (I suppose this is what I have defined at “Initialize Synthetic Volume”). So, it seems that "Change Resolution" is not affecting this case. 

I attach my pipeline here.

Bests,

Arash

[Michael Jackson]

The filter is correctly applying the change of resolution. The initial geometry is 256^3 with a resolution of 0.1. This means a physical dimension of roughly 0~25. When you applied the Change Resolution to 0.2 the physical dimension stayed the same at 0~25 BUT in order to achieve that the number of voxels is reduced half so that the grid is 128^3 voxels. See attached image which should help clarify what is happening.

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[Arash Imani Aria]

I tried with another version of Dream 3D, it gave correct files for DAMASK.

Bests,

Arash

[Michael Jackson]

Which version of DREAM.3D are you using that corrected the issue? What version of DREAM.3D were you using that was not working? Would be good to document that here in the help forums

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[Arash Imani Aria]

Hi,

Sorry for replying late.

Unfortunately, I do not remember which version I was using that did not produce the correct geometry files for DAMASK. But, I do remember that it was the latest version at that moment. 

The version that I use successfully now for creating different resolutions for unique geometry, is 6.6.58.

Bests,

Arash

[Michael Jackson]

Versions with “6.6.x” are nightly builds and unofficial but if it works for you then go with it.

 

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Mike Jackson

 

Hi,

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[Arash Imani Aria]

Hi,

One problem that I have now is that when I create 2500 grains with 256x256x26 resolution and change the resolution to 16x16x16, Dream3D crashes, however, when I first choose a 128x128x128 resolution and then reduce it to 16x16x16, it does not crash. What is the reason? Memory?

Bests,

Arash

[Michael Jackson]

Sounds like at the 256x256x256 you are just inside what your computer can handle and then adding in another geometry pushes it over the edge? Maybe? Could you send your pipeline?

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