Operating system: Windows Slicer version: 4.8.1 Expected behavior: Life-size bone models G’Day, I’ve just started using Slicer. I need to create 3d printed bone models to assist in surgical planning. I just want to confirm that stl models created in Slicer will be true to life. I have created…

So I made a model of the same skull in Philips IntelliSpace portal and then I compared all four models. Basically model made with 3D Slicer with correction of gentry angulation and automatic segmentation (Segment editor module) and made with IntelliSpace portal are the pretty much the same dimensio…

If you get different size, e.g. very large or very small, this probably an issue of different scaling so you may need to re-scale either in Slicer or in the other software e.g convert from meter to mm or vice versa.

Clinical scanners usually follow the DICOM standard in basic aspects, such as voxel size. There is no known issue in Slicer of reading these images correctly. 3D printers pretty much standardized on using mm as unit in STL files. So, not much can go wrong. Industrial, pre-clinical, and CBCT scanner…

If your measurements within Slicer are reasonable (ruler, segmentation’s volume etc) then it should be alright. We and our collaborators regularly print bones and other surfaces segmented from CT.

I know Slicer measurements are correct. It is just there are some tools out there (and probably some 3D printers) that use different scaling e.g. OpenSim , if I load something generated by Slicer, it will appear larger than it should be as OpenSim thinks the spacing is in meters not mm. I have to res…

[image] brhoom: I have to rescale it in OpenSim e.g. multiply by 0.001 or or resale it in Slicer using Transforms module Note that it is not necessary to transform your segments if you just want to change their scale for export. You can specify scale in “Export to files” dialog in Segmentatio…

Thanks for the info, I use Transform as the model should translated to the center of mass as well.

Why do you need to translate to the center of mass? We could include such centering in the export if it was useful, but you lose information (the true physical location) and I’m not sure what would be the advantage of doing that.

It is required for some simulation problems to have the model at the origin of the simulation space. It happens when the model is translated to the center of mass. I am working on extension to do number of this stuff including this, hopefully, I will upload it soon.

Last year I had an opportunity to work with Mimics trial version and made the same model that I made with Slicer previously. I got funny results, there was a bit difference between models segmented with these softwares as seen on the pic. I am not sure why that happened. (same DICOM data was used)! …

Maybe the CT was acquired with tilted gantry. When you acquire such CTs then you get a warning during DICOM import that image geometry may be incorrect. To load these tilted gantry CT-s correctly, “Acquisition geometry regularization” option must be set to “apply regularization transform” in menu: E…

Actual size of stl models

Support

lassoan (Andras Lasso) December 15, 2018, 3:55pm 16

If you can share the data set or at least image position and orientation DICOM fields (as described here) then we might be able to tell if there is a problem.

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Actual size of stl models

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