February 18, 2020, 9:56pm
This is again regarding surface scan registration issues with 3Shape Trios scans. The scan output is “stl”
when we try to superimposes the scans again it is very very difficult with 3D Slicer.
We used the Geomagic CX and the results were impressive and it was very quick. took less than one minute in a virtual machine. (Auto - without manual landmarks)
I tried the IGT Fiducial registration, CMF Surface registration and ROI registration.
CMF registration with max settings lot of time and the results are not very good. IGT fiducial registration is quick but we have to put the manual landmarks
Can some one with good experience with this can have a look at this please ? Perhaps help me where i am going wrong or is this not possible with 3D Slicer and will we have to stick to Geomagic for this step ?
February 19, 2020, 3:34am
I could get perfect registration results (0.025mm RMS error) with basic methods:
Crop the part of the rod that is not visible in the bone surface scan image (I used MeshLab for this for now)
Do a very quick, approximate registration on 3 points using Fiducial registration wizard, harden the transform
Use Model registration to fine tune the alignment
Good: All computations are instant (takes fraction of a second). Alignment is perfect.
Not so good: Manual cutting of non-common surfaces and manual prealignment is needed. It takes just 1-2 minutes, but requires attention.
There is a good chance that more sophisticated 3D surface template matching methods would work robustly without these manual steps (see for example
OpenCV surface matching algorithm).
February 19, 2020, 11:05am
Dear Prof Lasso,
Thank you and this helped alot. I did the trimming and i think now the results are very good. My mean distance after registration is 0.027.
Also i have no clue how you get the cross sectional view of the models ? How do i see the cross sectional views in red,yellow and green slices as you have shown in your post ? the way i was doing it was after registering, converting the models to segmentations, but this does not give a nice outline as in your photos.
February 19, 2020, 6:35pm
@lassoan – I figured that out !!! Models --> Slice Display --> Visible …
February 20, 2020, 3:52am
You also have full control over how segmentation is displayed in slice views: you can change the opacity of the filling and outline separately and choose outline thickness.
You can rotate slice views by enabling slice intersections and Ctrl + Alt + Left-click-and-drag in a slice view.