Saturday, 16 September 2017

Digital 3D Orthognathic Surgery with the OrtogOnBlender addon

Timelapse video of orthognatic planning steps

The first time I understood the concept of programming, it was in the year 2001, when I realized that a text with some codes was translated into a three-dimensional scene with some animated elements. I was astounded by it, as when I was three years old I realized that the water that was coming into the refrigerator freezer were those transparent pebbles my grandparents used in the juices they prepared for the family.

Since then I have always consumed some information about programming. Sometimes it would even cheer me up and write some codes, but the lack of practical use made me confine myself to just exercising my brain to understand some abstractions that involved that reality.


Many years and many books later, here I start teaching 3D computer graphics courses for the health area and realize that the organization of Blender graphic interface more confused than it helped the doctors in their didactic absorptions.

Faced with this difficulty on the part of the students, I motivated myself to create a methodology that would facilitate students' understanding in a field that proved to be quite challenging in the didactic context: orthognathic 3d digital surgery planning.

Automatically created deformation area

Unlike the other courses I had taught so far, orthognathic surgery, when taught in the "manual mode," where the student needs to understand detail by detail of commands, is almost impossible to apply to a short course. The problem is that it is precisely short courses that are the most sought after and not offering them translates into not generating income.

Together with Dr. Everton da Rosa, Dentist, orthognathic surgery specialist, I began to develop a series of small scripts that would help students automate one task or another. I did one, it worked, I cheered up... I did another, it worked out and another... I picked up a little and kept staggering and achieving, although not in the most elegant way, at least it was functional.

Jaw rotation

Blender uses Python for its scripts and this language is marvelous for anyone who wants to try to program, since the code is pretty clean. My excitement was growing to the point that I was fissured by the small challenges that were appearing.

Initially I intended to create a series of scripts, but realized that I could bundle everything into an addon, which would be installable in Blender. When programming and working with different objects and modes, I was intuitively understanding how everything happened, to the point of thinking of a solution, writing without referencing and code working!

Automatic creation of vertex groups

It was what I needed to become a hermit cyber... locked in the bedroom, just thinking about how to solve the problems and expand the functionalities. In unlikely five days, though not finalized, I was able to mount an addon sufficiently functional to simplify and automate a series of steps that comprise the planning of orthognathic surgery.

Interestingly, as a good nerd who follows the best practices of self-taught effort, I did not ask anyone for anything, I did not post on forums or social media groups on programming, nor did I ask for help from friends who are masters of language. I found everything I needed in the documentation, videos on Youtube, tutorials on the internet and, pampering ... in templates provided by Blender himself! In short, I did not ask for direct help, but I got it from the work and goodwill of people who wanted to help and made excellent materials, I am very grateful to all!

Jaw after osteotomy (Cork on Blender)

I intend to make the addon available soon (as we did with Cork on Blender), after testing it with my students. It is not yet complete, since it lacks the part of the surgical splint (a sort of guide for fitting the teeth) and some other activities such as automatic parenting with bone armature.

Even so, I am very satisfied, mainly for having implemented the automatic process of creating areas of influence based on osteotomy. With it, the cut bones, when moved make the soft tissue (skin, fat, etc.) deform. You can not imagine the challenge of teaching this in the "manual mode." Luckily it all came down to clicking two buttons, which is not bad!

Deformation radiated by the skull

I'm so happy and motivated that the will it gives is to go around programming and automating everything, but I felt on the skin another situation that is inherent in this kind of knowledge ... a code needs to be elegant and be prepared for exceptions and mine does not pass nor close to it. The trend now is to lapse the code and try to make it decent, worthy of being shared, used and improved by the community and interested in using it.

That's it, now I'm going because I had an insight on how to solve a problem in one part of the code... a big hug! : D
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