Moments in time of Building a Motion Capture System

Over the past few days I have been assembling a 12 camera Optitrack Flex 13 Motion Capture System in the Schools new Green Screen Room. The first set of images below are a photography journey of this process of the first day working on this. The consisted of setting up the workstation, mounting the cameras, wiring them up and positioning them with respect to the capture volume. Have written more about the process at the following blog.

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

Motion Capture Setup in Green Room

All the above images were form this past Thursdays work on the Motion Capture System, given that all the cameras were positioned all that was remaining was to calibrate the system and tidy up the cables, which I spent a good deal of this past morning and afternoon doing, as per the following images.

2013 11 16 MoCap

2013 11 16 MoCap

2013 11 16 MoCap

2013 11 16 MoCap

2013 11 16 MoCap

2013 11 16 MoCap

2013 11 16 MoCap

2013 11 16 MoCap

2013 11 16 MoCap

2013 11 16 MoCap

2013 11 16 MoCap

2013 11 16 MoCap

2013 11 16 MoCap

2013 11 16 MoCap

2013 11 16 MoCap

2013 11 16 MoCap

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Capturing an Instant in Time – Students Making a Splash

In the previous week with my class of about 100 first year computing students we looked at the process of panoramic photography and light-painting, hence were making use of long shutter durations. This week I thought it would be interesting to go in the opposite direction and capture moments in time of just hundreds or even thousands of a second. I had seen quite a few videos in the past, about capturing such imagery, using both flash and continuous based lighting, hence I gathered together a number of these videos and made a recent blog post about them.

This first image seen above is a composite of images taken from two of the three setups that were used. Firstly the stage was set for the capturing of soap bubbles gently floating down to earth. Next the students had a chance to drop some fruit and vegetables into an Aquarium. The final option was to pour some water into a wine glass and capture the some of the detail and beauty of flowing water that we overlook on a daily basis.

The day prior to class I set out to purchase some essentials, I began by getting some PVC tape, jugs, straws and glass scraper to clear the water from the aquarium after the splashes. Having being unsuccessful in finding soap bubbles, I ventured to another shop and was delighted to see they had a good variety, hence I purchased one of each set they had, this amounted to perhaps close to two liters of soap bubbles, so I was quite sure we would have enough for the photo-shoot. The final really large and important task was to find an Aquarium, so I headed in the direction of the beach to seek one out. I looked through quite a few different aquariums, and finally settled on a glass one of dimensions 24″ x 15″ x 12″ capable of holding about 65 liters of water. So with that I carted all this stuff back to the office.

Later that night I paid a visit to yet another shop to pick up some fruit and vegetables that should make a good splash in the aquarium. Also picked up some food colouring both yellow and blue for use with the water pouring into the wine glass setup. To capture any spillage from the glass I also picked up a paint tray! So that was more or less everything.

Given the class size was about 100 a video feed was setup between the green screen room in which the photography was taking place and the computer lab where all the students were working on some Photoshop and Illustrator tasks. That way they could see what was going on as the video feed was displayed on three projectors within the lab, hence they could move between one and the other depending on how busy the photographic session was. I have used this technique in the past on a few occasions and have found it to be very useful. All in all it took about an hour to set everything up for the shoot with the help of three students and the support team for the video feed.

The following photographs should give a sense of what was taking place in the green screen room with all three stages running concurrently. As you will see bubbles were being blown, peppers, strawberries and the like were being dropped into the aquarium & water was being poured into the wine glass. Five lights were used, two for both the aquarium and the bubbles, leaving just one for the wine glass. In total this amounted to the equivalent of 5320 watts of lighting keyed at a temperature of 5200 degrees kelvin.

The following set of images give a sense of what the room was like after a bit of tidying up was done and some things moved around a bit.

The next set of images just give a sense of the materials that were used for the photo-shoot taken around two hours prior to setting up the scenes. The large Nemo sitting happily on the aquarium will probably find a new home back on my desk but inside the aquarium, in which he fits nice and snugly. This of course has the added advantage of keeping him dust free once I find a suitable cover.

The final set of images include some of the water being poured into the wine glass along with the individual shots that were combined together in the first image of the post.

All in all I would guess that a few thousand photographs were taken in the course of a couple of hours. Its probably also safe to say that the students really seemed to enjoy the photo-shoot, especially given the room was such a hive of activity. Having a number of distinct but related tasks seemed to work well, one thing we didn’t do was to capture water drops falling and splashing into a pool of water, so that is perhaps something for next time, as one can use a few techniques for this alone. If you wish to see some of these images if greater detail, then you can take a look at the corresponding Album.

Setting up a Motion Capture System – Twelve Camera Flex 13

Back in June funding was made available by the University for the purposes of capital asset acquisition. The School of Computing put in a number of bids for equipment ranging from Eye Tracking and Networking to Video Production and Motion Capture. Two years ago when a similar opportunity came around, I suggested the idea of acquiring a Motion Capture System.  It really boils down to a question of cost benefit analysis. At that particular time any reasonable system would have been very expensive, so we ended up purchasing a Render Farm instead as we had quite a few students doing work in 3DS Max and the extra horsepower to quickly render out thousands and thousands of frames of animation seemed like a far more useful resource to have. I spent quite a bit of time during the summer of that year looking over render farm specs along with our Computer Systems Manager, we eventually settled on a 64 Core system.  At that very same time as well, we also purchased a fairly high end 3CCD video camera, about 6500 watts of lighting for the Green Screen Room, and a few other bits and pieces.

With this year’s funding we finally decided to take the plunge and get a Motion Capture System. Quite a bit of work has been done in the past two years regarding 3D modelling and animation. So a motion capture system would greatly add to this, providing us with the ability to readily animate the 3D characters produced by our students.

The time frame for putting the documentation together for the funding bid was quite tight so it transpired that I ended up putting the material together for the Video Production and Motion Capture System whilst I was out-with the country on holidays. Towards the end of August the proposals were signed off and approved, so I spent a fair bit of time putting together a finalised shopping list that should provide the school with some really interesting equipment to work with. Throughout most of the month of September various suppliers were found and the various items put in for purchase, with the last item (a piece of equipment for camera stabilisation) being finally sorted out just a few days ago. Colin our Computer Systems Manager tracked down a company selling the Flex 13 Camera system. It came on the market around April 2012, and has some interesting specs such as 1280 x 1024 resolution running at 120fps. After quite a few emails it was finally decided to go with a 12 Camera system with a Medium & Large MoCap Suit.

On Wednesday 26th Sept the Motion Capture System finally arrived, so I spent the afternoon going through all the parts and checking all was ok. On Thursday evening Eyad (a fellow lecturer) and myself went about setting up the system in our Green Screen Room. We got all the stands setup, cameras mounted, and all the cabling in place. Then we set about installing all the necessary software on one of two new Z400 workstations that we had purchased just a few months previously. The software installation was quite straight forward, but we ran into a problem with the registration of the software license. The error was that it couldn’t find a network. It was around 21:00 in the evening so we decided to leave it for the day and get it sorted out when the Systems team were in the next day.

Friday morning I called in to see Colin and Tommy to see if the software license issue could be sorted out. We first of all began by transplanting the workstation from C5 into the Green Screen Room, it was then necessary to enable some of the network ports in the room so we could get the machine up and running on the computer network. All went well and within a short while we were able to try getting the license sorted out. So with the Motion Capture system now powered up and connected to the Workstation and network connectivity established we tried entering all the license details, but ended up getting the very same error as encountered by Eyad and myself the night before. We were finally able to register online through a web browser and received the license key via email.  Within minutes of saving the license key to disk, the Arena Motion Capture Application was fired up, and the video feed from all the cameras started streaming in. So with the full system now operational we left it at that for the time being.

Yesterday (Saturday) Eyad and myself spent the afternoon at Uni aligning up the cameras correctly, calibrating the system, donning the motion capture suit and carrying out the first test of the system. Calibration consisted of Wanding the area to establish the capture volume, followed by the establishment of the ground plane and then the final phase of Skeleton Calibration i.e. getting the system operational for a specific individual. At the time we left the building (just before closing), we had managed to capture a bit of movement, I tried out the standard Calibration T-Pose followed by some golf swings (even though I don’t play golf).

As of now, the system is working well, though it will be necessary to go through the final Skeleton Calibration for myself, before it is finally configured correctly to accept motion data generated by my movements. It will be great to complete this final stage and see what the system can really do. All in all Eyad and myself have spent in excess of 20 man-hours (excluding the time spent going through documentation / tutorials) getting the system to its current operational state. Overall it was quite simple and straightforward to setup, just needing some time and patience. A large portion of the video production / graphics equipment on order is still in the process of being delivered, so hopefully it will all be in place within the next week or so. Sounds like an exciting semester ahead between now and Christmas.

The following videos above and below should provide an overview of some of the steps involved in the process. Quite a few more can be accessed from the following playlist showing most of the steps involved. Enjoy.