XROMM Day 1: Pig heads and C-arms

If you’re just tuning in, you may want to read my previous posts on what XROMM is and why I am thrilled to be learning this technique.

Today was a good, busy, productive day at the XROMM course.  Never let it be said that “simply” synching X-ray “movies” (cineradiography) is easy!  The students in the course are learning how to animate the three-dimensional jaw movements of a mini-pig, based on the research of Dr. Beth Brainerd and colleaguesThe XROMM site provides movies and animations of what we are attempting to duplicate.

You don’t simply take an X-ray movie and then transpose that into a 3-D animation, of course.  If you’re going to match up the three-dimensional models of the mini-pig skull to the chewing motions recorded on as cineradiographs, you have to get the animation program (MAYA) to synch with the frames of these movies.  And that involves a number of techniques including correcting for distortion (the tube that transmits the X-ray images to the camera has convex ends, which give the original footage a fish-eye lens distortion) and “registering” the simultaneous side and top or bottom views of the moving animal to virtual cameras and screens in MAYA.

In science, the tedious parts come from making absolutely sure you are doing everything to account for error and noise in your data.  This usually pays off with dividends in the end, but getting there is the hard work. Its not enough in this case to do all the technical things necessary simply to capture a moving animal’s skeleton in two planes.  Then you have to spend hours and days matching that raw data to your virtual skeleton — and all for a sequence of maybe 2-20 seconds in length.

Today we also were able to visit the two XROMM facilities at Brown.

Dr. Bonnan at XROMM facility

Dr. Bonnan in one of the two labs of the XROMM facility a Brown University. Note the two large, mobile X-ray machines to Dr. Bonnan’s left.

Physics came back to haunt me today, as part of doing the science of XROMM correctly and safely is putting knowledge of photons and radiomagnetic waves to good use. Physics was always a tough subject for me, but it is amazing what you can learn and apply when you really want to do something and when doing it incorrectly will result in long-term injuries from X-ray irradiation!

One of the rooms had mobile C-arm X-ray machines that demonstrate very well the basic concept of what you do when you capture the motions of an animal.

Small C-arms at XROMM

Two small C-arm X-ray machines in one of the XROMM labs, positioned perpendicular to one another. One is facing left, and the other is pointed away from you in this photo.

All of the XROMM faculty and staff have been wonderful and saintly in their patience with us as we learn a technique that is often as frustrating to learn as it is to explain many times over and over again.  A big thank you for their patience and help today … and I think my eyes are starting to uncross now.

To give you an idea of the time investment necessary to convert 2-D cineradiographs into 3-D moving models, consider this: we spent most of our time today simply registering points and synching virtual camera views … there has been no animation yet!

I see great potential for research and student involvement with XROMM, and I’m looking forward to having a chewing mini-pig skull in the next few days.

Stay tuned …


2 thoughts on “XROMM Day 1: Pig heads and C-arms

  1. Pingback: XROMM Day 2: This little piggy bites … in 3-D | The Evolving Paleontologist

  2. Pingback: XROMM Days 3-5: Data, data, data | The Evolving Paleontologist

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