Mac mini meets iPi

heilei · **Posted:** Thu Jan 02, 2014 1:05 pm

Hello all,

I thought I'd share my Mac-related experiences (which have been extremely positive so far), now that I'm starting to take my very first steps with iPi and MoCap.

Hardware:
Mac mini (Mid 2011), 2x2 core i5, 2.5 GHz, 8 GB RAM, AMD Radeon HD 6630M, 500 GB HD (Toshiba, 5400 rpm)
4 x Playstation PS3 Eye

Software:
Mac OS X 10.9.1
Windows 7 Professional (installed via Boot Camp 5 to a separate partition on the internal HD)
iPi Recorder

I expected all kinds of trouble, either with Boot Camp, the slow(ish) hard drive, the USB buses or my general lack of hardcore hardware knowledge. But no, everything just works! I am able to record 4 simultaneous 60 Hz streams from the four PS3 Eyes. I haven't yet installed iPi Mocap Studio or recorded anything useful, but at least visually the four videos seem just fine (when played back with iPi Recorder).

I'll report more as soon as I get enough room to record something real, but so far, a big thumbs up for you iPi guys/gals! Hopefully this is also an encouraging sign for those trying to make iPi stuff work with Apple hardware! (Even with a two-year old Mac mini; I was afraid I'd have to drag my Mac Pro monster downstairs for recording... the old, HEAVY Mac Pro, that is...)

Regards,
HeiLei

heilei · **Posted:** Sun Jan 05, 2014 11:16 am

Ok, more newbie experiences, day 2:

PS3 Eye cameras: yes, they do have an extremely good price/quality ratio and they really deliver a steady image stream, but boy they are a royal pain in the a** to handle and to STAY PUT! They are very light, and there are no holes or other fixtures in the base. Nice job Sony. (Sorry for the frustration, but I've now spent most of the day with velcro, rubber bands, double-sided tape and almost every other household keep-things-together stuff...) The cable from the camera, on the other hand, is very heavy-duty and most of the time, the position and angle of the cable also determines the direction of the camera. Lesson learned: do NOT touch the cables after you've adjusted your camera angles.

Required space: I'm nearly 6'4" (192 cm) and that's not good. Another lesson learned today: the taller you are, the more space you need, if you want to fit yourself in the frame, from head to toe. You need to set the cameras quite a distance away from the actual action space. 4 m x 4 m is NOT enough for the complete setup, if that's wall-to-wall. At least not for a tall dude like yours truly.

Ok, that's all for now. The story continues...

Greenlaw · **Posted:** Mon Jan 06, 2014 12:15 am

Re: the PS3 Eyes, yeah, by themselves, they're not very stable for positioning. I eventually modified mine by drilling out the small hole in the metal baseplate (it's under the label,) and threading it with a Helicoil kit so that I could mount it on a standard tripod screw. (I'm actually using light stands which are much cheaper and just as stable as a good tripod but same idea.)

There are 'official' mounting brackets available but if you're handy with a drill and vise, modding the camera base is easy to do and much cheaper. (The Helicoil kit was about $15 when I bought mine a couple of years ago, and a single kit is good for 12 cameras.)

G.

Update: I just checked on the kit...it costs $19 now but still much cheaper than the special buying brackets. Here's the link for what I bought:

http://www.amazon.com/gp/product/B0002S ... UTF8&psc=1

Based on my Amazon purchase order date, I must have modded my PS3 Eye cameras back in 2010. Man, has it been that long? That must mean I've been using iPi Mocap studio for 5 years now because I started out with the Logitech cameras at least a year before the PS3 Eye cameras came along. I guess time flies when you're having fun. :D

Greenlaw · **Posted:** Mon Jan 06, 2014 12:28 am

Regarding the space requirements, yes, this has been an issue for me too. It's one of the many reasons why I'm a big fan of the multi-Kinect configuration. Multi-Kinect is much easier to set up and use, and it requires far less space. All the mocap for 'Happy Box' and the 'B2' excerpt was shot in our living room using dual Kinect, which is really convenient because our computer room adjoins it. I recently added a third Kinect to finish 'B2' and this triple-Kinect configuration appears to work fine in this space too. (I still need to fully test this setup but we're too busy finishing a third movie (non-mocap) right now.)

By contrast, I cannot fit the PS3 Eye configuration in the same room in our house. I can fit it into our stage in the garage but then the capture area isn't appreciably larger when shooting with PS3 Eye in that space. If I need to use the PS3 Eye configuration again, it will likely be outdoors on an overcast day.

Hope this info is helpful.

G.

heilei · **Posted:** Mon Jan 06, 2014 9:25 am

Thanks for the tips, Greenlaw. I shot my very first takes today, and again, a valuable lesson learned: do not change the camera USB cable order AFTER the calibration... Luckily I found a helpful hint somewhere on these forums: you can manually reorder the cameras in the scene XML file, if you unintentionally switch the cable order somewhere along the process (as I did...)

Tomorrow I'll see if I managed to produce something usable or not. Fingers crossed...

Greenlaw · **Posted:** Mon Jan 06, 2014 10:34 am

As you've discovered, it's important not to change anything with your configuration after calibration.

This generally means physical placement and orientation of the cameras but it's good practice to avoid changing anything about your configuration after calibration and before you record your motions.

As a precaution, I always recording another calibration file after my recording session. Sometimes, I may record multiple calibration files during the session (like every 15 - 20 minutes or so,) or if I suspect something has been altered by accident. Few things can be more disheartening than spending several hours recording mocap, only to lose it all because of bad calibration data.

Naturally, if you change your configuration on purpose, you should re-calibrate then too.

One more tip: iPi Recorder allows you to name your files so I like to append calibration data with 'Cal' so I can identify them immediately. Also, if you're using a computer with a good graphics card, you should occasionally test your calibration file before recording your motions. On my system with an old GTX 460, it takes only a couple of minutes to process a calibration file and it's well worth it for the peace of mind.

G.

heilei · **Posted:** Tue Jan 07, 2014 2:12 am

Thank you (again) for valuable tips, G. I ran a few tracking tests yesterday, and it seems the results are actually pretty good! There are some occlusion problems, though. Sometimes the arm gets mixed up with the torso, which is probably due to my clothing. I wore black trousers and a dark grey shirt; I probably should have used brighter and more distinguishable colors.

I wonder if the results get better if you really go wild with your wardrobe, like bright blue shirt, green slacks, red socks/shoes etc.? If you're gonna look like a clown, you might as well do it properly, right? :-)

Anyway, I have to say that this has really been an extremely positive experience so far, because my expectations were not too high ("Playstation cameras? Motion capture at home in your living room? Yeah, right...").

My long-term goal is to create a short robot-based animation film (with Cinema 4D). Everything else is more or less ready (script, 3D models, rigging etc.), so my next step is to test the workflow and take the BVH file from iPi to C4D.

Greenlaw · **Posted:** Tue Jan 07, 2014 10:05 am

For PS3 Eye, colors aren't critical, it's really more about contrast. What works best is black short sleeved t-shirt over a a green or red long-sleeved shirt. (Use the color that contrasts with the background best.) The black shirt minimizes shadows on the torso, which can confuse the tracker, and the color long sleeves separate the arms from the torso.

Long pants like blue jeans work well but not baggy pants. Comfortable shoes like sneakers are fine for shoes. (When I used PS3 Eye cameras, I just wore socks.)

For Kinect, colors are not important at all, just avoid shiny clothing. As with PS3 Eye, clothing should be close fitting for an accurate read of the body. I find that wearing large hiking shoes or boots helps with dual Kinect because the system tends to subtract too much of the feet when it defines the ground plane.

G.

heilei · **Posted:** Wed Jan 08, 2014 3:49 am

Ok, here we go, my very first motion-captured clip. Yours truly sitting on a chair and then getting scared of something...

https://vimeo.com/83664307

No manual corrections done, just a straight import as BVH to Cinema 4D + a quick render. The hands have some kind of stutter or jitter, and the guy in the clip moves like a 80-year old (and I'm not THAT old...) Other than that, I'm pretty pleased with the result.

Greenlaw · **Posted:** Wed Jan 08, 2014 9:04 am

Nice! Glad you got it working. :)

Mac mini meets iPi

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