# Two STL models of Intra- oral surface scan alignment and volume measurement **URL:** https://discourse.slicer.org/t/two-stl-models-of-intra-oral-surface-scan-alignment-and-volume-measurement/8365 **Category:** SlicerCMF **Created:** [September 10, 2019, 2:18pm UTC](https://discourse.slicer.org/t/two-stl-models-of-intra-oral-surface-scan-alignment-and-volume-measurement/8365 "2019-09-10T14:18:00Z") **Posts on this page:** 3 **Page:** 1

### Author: ![manjula](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/manjula/32/80981_2.png) [@manjula](https://discourse.slicer.org/u/manjula) #### Post date: [September 10, 2019, 2:18pm UTC](https://discourse.slicer.org/t/two-stl-models-of-intra-oral-surface-scan-alignment-and-volume-measurement/8365/1 "2019-09-10T14:18:00Z")

Hi, Our Input - 2 STL surface scan models (PreOp and Post Op) - from the 3Shape surface scanner. We have two problems. 1. Need to accurately align the pre and post op surface scans ? (they have fixed landmarks) 2. Need to measure the change of volume in the region of interest ? ( the volume of bone resorption) So far, we have install CMF registration and, as you can see from the pictures the alignment with CMF surface registration is not accurate enough. ![PreOperative](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/0/b/0b21e83b01606bbf24344a6705dad93c0af5537b.png) ![SuperImposed](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/0/d/0dfd655d9175ff97f94b98986013de29a921c1a6.jpeg) We need to improve the accuracy of the alignment and we are unable to do it so far. Can someone help us with accurate alignment/superimposition of the two scans ? Next we need to measure the change in the bone volumes in the circled region. That is the difference of bone volume in preoperative and postoperative scans. ![Volume](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/9/b/9be3bbff36435aa9258599e0989fd95dcb183809.jpeg) Is this can be done in 3d Slicer ? Looking forward to hearing from you all. Thanks ---

### Author: ![cpinter](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/cpinter/32/7995_2.png) [@cpinter](https://discourse.slicer.org/u/cpinter) #### Post date: [February 28, 2020, 3:17pm UTC](https://discourse.slicer.org/t/two-stl-models-of-intra-oral-surface-scan-alignment-and-volume-measurement/8365/2 "2020-02-28T15:17:48Z")

A post was merged into an existing topic: [STL models - Alignment and Volume measurement](https://discourse.slicer.org/t/stl-models-alignment-and-volume-measurement/8364) ---