Forums
New posts
Search forums
What's new
New posts
Latest activity
Articles
Members
Current visitors
Log in
Register
What's new
Search
Search
Search titles only
New posts
Search forums
Menu
Log in
Register
Install the app
Install
Forums
Lab talk, the good, the bad, and the ugly
Dental-CAD
Designing a Restoration: Free and Open Source
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Message
<blockquote data-quote="patmo141" data-source="post: 27124" data-attributes="member: 2560"><p><strong>Crease and Curvature</strong></p><p></p><p>Next idea.....the kavo margin should be the sharpest line angle anywhere nearby unless you want a cracked tooth. This should give us a nice way to find the margin mathematically (meaning someone else probably has thought of that and there are existing tools! Indeed, MeshLab has some filters for this...I don't truly understand them all). So, all we have to do is look for sharp curvatures and this should indicate our margin. Turns out, curvature is a nice "continuous" thing and when you get to discrete meshes, it becomes different (difficult). One thing we can calculate easily is the angle between faces. Eureka! I told Meshlab to select all edges with faces whose normals were further further than 90 degrees apart. When I did this, it selected NO EDGES! not one! Then i realized, the faces are on the order of microns apart. If your surface is turning 90degrees over the course of a few microns, that would be intense curvature. So, how "sharp" something looks depends on how zoomed you are, or how big of "steps" the surface takes whilst turning through a certain angle. After playing aorund, I found that the margin had "creases" around 30 degrees. Unfortunately, some of the bumpy structure of the tooth also has faces which qualified as a "crease." Not a huge deal, but that just means another "cleaning" step later. I'm still wanting something better...</p><p>[ATTACH=full]995[/ATTACH]</p></blockquote><p></p>
[QUOTE="patmo141, post: 27124, member: 2560"] [b]Crease and Curvature[/b] Next idea.....the kavo margin should be the sharpest line angle anywhere nearby unless you want a cracked tooth. This should give us a nice way to find the margin mathematically (meaning someone else probably has thought of that and there are existing tools! Indeed, MeshLab has some filters for this...I don't truly understand them all). So, all we have to do is look for sharp curvatures and this should indicate our margin. Turns out, curvature is a nice "continuous" thing and when you get to discrete meshes, it becomes different (difficult). One thing we can calculate easily is the angle between faces. Eureka! I told Meshlab to select all edges with faces whose normals were further further than 90 degrees apart. When I did this, it selected NO EDGES! not one! Then i realized, the faces are on the order of microns apart. If your surface is turning 90degrees over the course of a few microns, that would be intense curvature. So, how "sharp" something looks depends on how zoomed you are, or how big of "steps" the surface takes whilst turning through a certain angle. After playing aorund, I found that the margin had "creases" around 30 degrees. Unfortunately, some of the bumpy structure of the tooth also has faces which qualified as a "crease." Not a huge deal, but that just means another "cleaning" step later. I'm still wanting something better... [ATTACH=full]995[/ATTACH] [/QUOTE]
Insert quotes…
Verification
Who do we work for?
Post reply
Forums
Lab talk, the good, the bad, and the ugly
Dental-CAD
Designing a Restoration: Free and Open Source
Top
Bottom