# Alpaca error in 'Run Subsampling'

**URL:** <https://discourse.slicer.org/t/alpaca-error-in-run-subsampling/22552>\
**Category:** Support\
**Tags:** registration, extensions-manager, python\
**Created:** [March 16, 2022, 8:53pm UTC](https://discourse.slicer.org/t/alpaca-error-in-run-subsampling/22552 "2022-03-16T20:53:32Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Christianne](https://avatars.discourse-cdn.com/v4/letter/c/f14d63/32.png) [@Christianne](https://discourse.slicer.org/u/Christianne)\
**Post date:** [March 16, 2022, 8:53pm UTC](https://discourse.slicer.org/t/alpaca-error-in-run-subsampling/22552/1 "2022-03-16T20:53:33Z")

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Operating system: Windows 11  
Slicer version: 4.13.0-2022-03-10  
Expected behavior: Run subsampling  
Actual behavior: Error in running subsampling

Hi all,

I’m new to SlicerMorph. I downloaded it a few days ago, but unfortunately the Sandbox extension wasn’t available. SO I ended up downloading the SlicerMorph Nightly version. That worked and I was able to get all the extensions I needed.  
Going through the tutorial for running Alpaca ([here](https://github.com/SlicerMorph/Tutorials/tree/main/ALPACA)), I ran into an error when I click ‘Run Subsampling’:

:: Loading point clouds and downsampling  
Traceback (most recent call last):  
File “C:/ProgramData/NA-MIC/Slicer 4.13.0-2022-03-10/NA-MIC/Extensions-30699/SlicerMorph/lib/Slicer-4.13/qt-scripted-modules/ALPACA.py”, line 352, in onSubsampleButton  
self.targetFeatures, self.voxelSize, self.scaling = logic.runSubsample(self.sourceModelSelector.currentPath,  
File “C:/ProgramData/NA-MIC/Slicer 4.13.0-2022-03-10/NA-MIC/Extensions-30699/SlicerMorph/lib/Slicer-4.13/qt-scripted-modules/ALPACA.py”, line 903, in runSubsample  
source\_down, source\_fpfh = self.preprocess\_point\_cloud(source, voxel\_size, parameters[“normalSearchRadius”], parameters[“FPFHSearchRadius”])  
File “C:/ProgramData/NA-MIC/Slicer 4.13.0-2022-03-10/NA-MIC/Extensions-30699/SlicerMorph/lib/Slicer-4.13/qt-scripted-modules/ALPACA.py”, line 944, in preprocess\_point\_cloud  
from open3d import registration  
**ImportError: cannot import name ‘registration’ from ‘open3d’ (C:\ProgramData\NA-MIC\Slicer 4.13.0-2022-03-10\lib\Python\Lib\site-packages\open3d\__init_\_.py)**

Open3d didn’t have any issues installing when I had first opened Alpaca. I opened the python interactor window, typed  
import open3d  
`open3d. __version__ `

and the version I have installed is 0.15.1

Alpaca didn’t automatically install pycpd, so I went ahead and installed it : pip\_install(“pycpd”)  
But I keep getting the ImportError everytime I try and click run subsampling. I’ve tried uninstalling open3d, then reinstalling. I’ve also tried installing open3d versions 1.10 (which doesn’t even want to install) and version 1.14.1, but the error persists.

 ![Landmarks](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/2/8/288ce008a18313292d33f14803695c6b59c15203.jpeg)

I also don’t have some features within the Single Alignment tab that the tutorial has, such as the ‘Select subsampling voxel size’. I don’t know if that’s going to harm me down the road.

Any suggestions on how I can get past the ‘Run Subsampling’ without encountering this error?

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<div class="post-metadata">

**Author:** ![smrolfe](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/smrolfe/32/3659_2.png) [@smrolfe](https://discourse.slicer.org/u/smrolfe)\
**Post date:** [March 17, 2022, 5:33pm UTC](https://discourse.slicer.org/t/alpaca-error-in-run-subsampling/22552/2 "2022-03-17T17:33:56Z")

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@Christianne thanks for reporting this. The fix for this issue in the Preview version will be available later today on our repository, or in the extension manager tomorrow.