Learn From My Mistakes - Some tips and pointers for a better mocap session | Perception Neuron by Noitom

Learn From My Mistakes - Some tips and pointers for a better mocap session

You are here

11 posts / 0 new
Last post
TorQueMoD
Learn From My Mistakes - Some tips and pointers for a better mocap session

Hey all,

So I've been using my Perception Neuron suit for the past 3 weeks and I want to start by saying this suit is AWESOME! If you're on the fence about whether or not you should buy one, hop off on the Yes side and buy one now. You really won't regret it.

That said, there's a slight learning curve to using the suit effortlessly and you're never going to get perfect results. I ran into my fair share of issues over the last few weeks and I thought I'd post about my experience here so that everyone else can benefit and learn from my mistakes. What follows is a list of things to look out for and advice in no particular order.
 

  • If you're not sure if you should get the full 32 neuron edition or the less expensive 18 neuron edition, spring for the extra $500 and get the 32. The benefit of not having to animate the fingers by hand can be easily under-rated and  will save you so much time. I've also found that without them, the hand movements are less acurate.

 

  • When you first open your suit you'll find that each of the bags is marked with a graphic to let you know which part of the body the contained mounting points should attach to. When you get to the bag marked as ARMS (32 neuron suit) do not be alarmed (or dismayed) when you reach in and pull out two extra gloves. I thought this meant that there was a slip up at the packaging factory and lost an entire week because I didn't look any further. STUFFED INSIDE these gloves are two arm bands that you will strap to your biceps. The reason for this design is because this is the default package of 18 neurons and for the 32 neuron set, they just throw in another bag labeled hands with all of the finger mounting points. That and you may want to capture without the finger slots getting in the way. I understand the reasoning but man did it ever confuse the heck out of me.

 

  • As with the previous point, make sure you also take note of the fact that each mounting point has a label on the back specifying whether it is the RIGHT or LEFT version. If you accidentally swap these (as I did with the biceps pieces) you'll get some really wacky results.

 

  • When you first open your suit, you'll notice that some of the node mounting points (hips, toes etc.) have flat black "caps" covering them. Leave these where they are!!! In fact, if you really want to make your life easier, take them out, mark them red or silver with a permanent marker and then put them back where they were. The suit uses universal mounting points throughout it's entire design and these caps were placed there to let you know that you shouldn't be adding neurons to these spots. I stupidly pulled off the caps and then got confused later when I didn't have enough neurons to fill all the mounting points. I had two in the hips on my first test run that did NOT need to be there.

 

  • If you're using WiFi (which is pretty much the ONLY way you should use the suit) another important accessory to buy along with your Power Pack is a belt clip for it to sit in. Sure, you can put it in your pocket, but with straps around your thigh and waist, it will be a lot easier to clip it onto the belt. If you're like me and wear under armour without pockets while capturing, then it's even more important. You need to keep it out of the way of all of your limbs too so putting it closer to your butt will help.

 

  • The setup guide for where to place the neurons on your body is a little vague and quite confusing at first glance. Even looking up answers on google doesn't help much more as they mention a chest point that doesn't exist and even the tutorial videos skip over exactly where you should slot youur neurons in. The correct places are as follows: one on each foot, one on each shin, one on each thigh, one on your lower back (back of the belt) one on the center of the back, one on each of the shoulders (these mounting points should be slid all the way flush with the center back mounting spot and not rest on top of your traps like the diagram shows), one on the head, one on each biceps, one on each wrist (bottom slot on the gloves) one on the back of each hand, two on each thumb, two on the index fingers and one on every remaining finger. For those who can count (unlike me) this totals 31 neurons for the full body capture. The spare neuron is apparently for a tool or object that you can pickup and hold, however I have no idea how you're supposed to connect this tool to the system since there aren't any empty connection points on your hands. Either way it's nice to have a spare.

 

  • If you're planning to use 3D Studio Max as your animation package as I am, the bvh for 3ds max exporter from the Axis Neuron Pro Software (as of October 17th, 21016) is broken. I reported the issues I was experiencing to Noitom and they have assured me they are working on a fix. Until then, don't dispare, you can still use Motion Builder and the fantastic (and simple) plugin provided by Noitom to get your animation working in Max. Just export your biped from max as an FBX file and you can import it into MoBu and then transfer the animation to your own skeleton. This takes a bit of work, but might be a preferred method if you want to tweak the animation in MoBu anyway. When exporting your animation from MoBu, be sure to save it as an FBX (ASCII). Once you've done this you can import the animation into the scene containing your biped in Max and when the FBX import window pops up, under the Include rollout you'll see a drop down for File content. Setting this to Update animation will cause any bones of the same name to be updated accordingly and will also update the biped's bones to match. I've been using max since 2000 and I didn't know about this feature until this week. Sadly, renaming the bones of your biped to the same names used in Axis' skeleton doesn't work.

 

  • When recording your motions, don't make the mistake I did and record the entire performance in one take. This will cause several problems that are not worth the headache (3Ds Max really doesn't like to let you work on a scene with 10,000+ keyframes and I have 32gb of ram) and you'll end up re-recording everything in frustration once you realise how much easier it will be (as I did). ALWAYS record each sequence as it's own separate file. If the animation is short, then you can use hand gestures to let you know when one take ends and another begins. For example, on the really short sequences (waving hello) I'll act out the motion and then stand still for 3 - 5 seconds before raising my right arm and giving a peace sign to let my future editing self know that I'm about to start the second take. If I mess up a take entirely but don't want to stop recording, I'll raise both my hands in an X and shake them back and forth to signify a bad take. These cues are really important since you're not capturing any sound with the performance and you'll have no other way to figure out when a scene ends. 

 

  • In keping with the previous suggestions for how to make your editing life easier, start and stop every animation in an "idle pose" rather than a T-pose. A T-pose is great for rigging a character, but you don't need this in your animation as you can easily create a t-pose when rigging. For the animations, if you want to be able to blend them into each other more seamlessly, a neutral idle pose at the start and end is a lot easier to work with.

 

  • If you notice slight issues with your character's posture (my character always seems to be leaning forward) don't waste time worrying about it if you're not using the suit for live performances. This is something that is incredibly easy to adjust with an animation layer in your animation package and it's better to just use the suit for the base performance capture that you hand tweak later. You'll drive yourself crazy trying to capture the perfect performance. 

 

  • Continuing from the point above, if you find that your character is standing with his feet too far apart or too close together, (or any other postural issues) you need to adjust your real world feet (or other body parts) accordingly while running the suit's calibration. If your character's feet are too close together as mine were, then move your feet closer together while calibrating. This may seem counter intuitive but the calibration sets up the neutral pose of your character so if you do this with your feet shoulder width apart, then when you stand with your feet closer together during your performance, the charcter's feet will end up crossing. Vice versa if you calibrate with your feet too close together. It's worth taking some extra time during calibration to work out these kind of issues and after the first calibration you'll be able to use the character as refernece to help you work out how to adujst your limbs appropriately.

 

  • While capturing your performance, be sure to have some sort of real world reference on your "stage area" with you so that you can come back to roughly the same position if you move away from the intial spot (I placed a small table in front of and behind me as reference). Also be sure to have your partner (you need someone else to hit the record button since the neurons are so sensitive to magentic interference) Zero out the character before hitting the record button. This ensures that if you're standing 6 inches to the left of your reference point without realizing it, the animation will still be at the world's zero regardless of where in the room you're standing. This also fixes facing issues and will save you a lot of headache having to tweak the animations later. 

That's everything I can think of for now. I hope this info will be of use to other members of the community and I want to say a BIG THANK YOU to Noitom for creating such an awesome and affordable motion capture solution!

-Peter
 

IanL

Some useful tips there Peter.  Thanks for taking the time to put this together, I'm sure others will find this useful.

Jonas_molgaard

Thanks for the write up TorQueMoD, i haven't decided to buy the PN's yet, but your post sure brings me closer to placing an order. Very nice that you have all these descriptions of the mistakes you did and problems you ran into. Super usefull!

Strob

Very nice tips! Thank you Peter!

About the max bvh being broken, I just noticed a problem with the thumbs which seem no to animate when importing in max. Other than that it seems to work. What was broken on your side?

fabricio.chamon

thanks a lot Peter, great walk through. I`ve been using it for one week, and If I may add some stuff to your list that would be:

- yes, go for the 32 sensors pack. Unfortunatelly the company I work for got the 18 sensors pack, and it is really bad not having the aditional hand details. Although for an upgrade your should spend about USD 540 which is not much more than the extra 500.

- If you are alone, it is better to connect your neurons before wearing the suit. It seems logical, but my first tought was that some of them may break or fall during the process. When I finished puting all the straps and gloves I realised I couldn`t reach many areas on the back. that was funny and frustrating.=)

- when calibrating, be sure to not wear the suit before the steady pose. It is so much easir not having to try and stand still (and also more accurate), so just leave it on a table or something and calibrate only this pose, then wear the suit and calibrate A, T and S poses.

- before wearing your suit, make sure the sensors are all in the "breathing" state (meaning connections are ok), just then put all the stuff on your body. If any of them are flashing then there`s something wrong, take it off and re-connect.

- again, if you are alone, make sure to have a mirror or any reflective surface (office windows for example). You may need it to check whether your sensor are symmetrical and in good positions, make sure to reach the right cables on the back area and also re-check if you have all leads "breathing".

- for motion retargeting either use motionbuilder, or like me use maya. For maya I`ve found 2 ways:

a) using humanIK.
a.1 - Import your mocap motion in fbx, go to frame -1, select the whole skeleton hierarchy (right click on the hip bone>select hierarchy) and on the menu choose Modify > Reset Transformations. Then key all rotations/translations.

a.2 -  open humanIK window and create a new character definition. map all the bones, and make sure to lock the skeleton definition at the frame -1. (lock icon)

a.3 - bring in your charcter, create a new definition for its rig and map the bones. Or alternatively, create a humanIK quick rig (works great and it is as easy as mixamo auto-rigger).

a.4 - with everything imported and mapped, on the humanIK window just select your character in the "Character" list and the mocap in the "Source" list and you are set.

b) using Nicolas Esposito`s script if you are using mixamo characters

b.1 - It is a really simple thing, just a mel file that is a 1-click solution that transfer motions easy. I had some problems with namespaces (your character it has to have the "mixamorig" namespace), but that was too easy to fix using the namespace editor. Also there are still some feet sliding if your character proportions are somewhat off, but he`s already working on that.

b.2 - he sells the script, so if you want to buy just contact him as I did. He also offers a free script to UE4, that you can check here: https://forums.unrealengine.com/showthread.php?133780-Mixamo-to-UE4-Mann...

hope that helps.

 

carlBrutananadi...

...some of the node mounting points (hips, toes etc.) have flat black "caps" covering them. Leave these where they are!!! 

Great thread! The 'etc' in the above quote should probably be removed to avoid confusion. To clarify, there are two caps on the left and right index knuckles which may be replaced with sensors. I assume the caps in the right/left hips and toes should probably be left in placed as none of the documentation depicts their use. 

In all, I have 31 sensors installed on the body kit (with two caps installed in the left/right hips and two in the left/right toes) and 1 sensor left over which I believe is for use with an external prop.

...another important accessory to buy along with your Power Pack is a belt clip for it to sit in. 

I don't believe there is an official accessory called the 'Power Pack' nor have I found a belt clip. I've found a portable battery is more secure tucked in a pocket anyways.

My PN32 came with two straps attached to the belt that I have not found referenced in the documentation. Does anyone recognize these or know what they're used for?  
Image of straps: http://i.imgur.com/tnW1L58.jpg

Answer: The straps are for the groin to ensure the base (rear center hip) sensor stays in place. Source:  https://youtube.com/watch?v=2EdicJS63gQ&t=63
 

carlBrutananadi...

cannot-delete-my-own-reply.

embaldwin

Thanks Peter. 

Has anyone else had any troubles with the glove calibration? (i.e if you attempt to clap your hands in the capture are not clapping?)
Any tips on how to fix this cal?

danielc
danielc's picture

If you are experiencing issues with Clapping, please check the body size profile you are selecting. Axis Neuron includes several presets. Please select a body size profile that fits best for you, keep in mind that the profiles are separated by HEIGHT in CM's.
Select the Body size and then perform your posture calibration.

embaldwin

Hi DanielC, 

I've already done this with my own body profile and my hands still cross over... as I'm attempting to record sign language (AUSLAN) which requires two hands I'm unable to get the fine motor movement. This includes using one hand to point at another(s) finger, clenched fists, etc... which don't work as they either cross over or are out of place. 

Do you have any other tips on how to fix this? 

Thanks!

Nourzx

Great article as a new user it's so helpful :)

About Perception Neuron

We are part of Noitom Ltd. and dedicated to the development of motion capture systems for entertainment, sports, science and medicine.

  • 278 NE 60 St
    Miami, Florida 33137
  • (305) 521-3124
  • +86 10 82055391 ext. 852
  • contact@neuronmocap.com

Latest Posts

Flickr Feed

Check out our photo album from events, fans, and just random fun stuff.