New Blender 2.8 Chordata Node System Addon

daylanKifky

The second beta of the addon is out!

Here's the changelog:

Chordata addon v1.0.0-B2 Changelog
==================================

Armature node:
- add smooth filter
- add root bone height
- add timed calibration
- add Armature out Socket

Record node:
- add option to use the current accion
- use Armature in Socket

Notochord node:
- include pre-registered captures on Demo mode```

AxonSpark

daylanKifky So I did a full biped test with the new add-on and it looks like the knee bend problem is still an issue. Before I start a new testing thread, I wanted to ask:

Would it be helpful to use the Dump Node to gather some data for you? If so, which boxes should I be checked?
Would further spine or spine & leg tests help at all? Or maybe setting up groups of 3 K-Ceptor models in order to see if the axes align properly?

I made notes on where all the sensors were placed, so hopefully that'll help with troubleshooting.

daylanKifky

AxonSpark
Hey!
I think starting a new clean thread with just the problem that you are currently having would be a good idea.

I still think this is a magnetic problem. Have you ever tried the suit outside your flat? sometimes modern apartment buildings have an incredible amount of iron in the structure which distorts the magnetic field inside them. This would explain the errors in heading you experiment, which are always located at the lower part of the body (thus closer to the floor, where big iron beams support the structure).
We are currently working on a magnetic correction algorithm that should help to compensate this type of disturbances. Yet, having a test in a different environment would help confirm the hypothesis.

A way to get an idea of your vertical magnetic disturbance profile would be this:

Start the notochord with the --raw flag, and just one KC attached
In the Blender addon Use the Vector node to visualize the incoming magnetic vector. If you keep your KC in the same orientation and move it around the arrow should always point in the same direction (heading north, and about 65° ~ 70° off from the horizontal)
Keeping the KC in the same orientation pull it above your head, as far as your arm (and the KC cable) allows you, then slowly pull it down up to the floor.

Did the arrow changed direction during this process? If it did, was the angle of heading change similar to the angle of heading error you get in the knees?

PS: there's a bug on the vector node, it sometimes doesn't create the correct list of incoming KC names. If this happens to you just plug a Testcube node in the same tree, and it will populate the list that is used also by the Vector node.

Another thing to keep in mind: Magnetometers are affected by torsion. This is a known fact, but we recently made some tests, and the influence of just a small torsion can be huge. Are you by chance calibrating your sensors outside the case, and then screwing them? Or perhaps adjusting the screws from time to time? Those actions might change the torsion of the PCB, and invalidate the previously done calibration. I'll upload a demo video soon

AxonSpark

daylanKifky I'll have to wait until social distancing/lockdowns have subsided before trying the suit outside of my apartment. The building I live in is over 100 years old (converted hotel from the early 1900's), so I'm not sure how much metal it contains, but there could be a fair number of pipes under my floor. I'll try running the test you suggest to determine if that's what's causing my issues (although it's odd that it sometimes affects one leg and sometimes both).

As for your questions about torsion, I do not remove the K-Ceptors from their cases for calibration. I put calibration markers on all the project boxes, so I wouldn't have to remove them. I'm also not adjusting the screws, as nothing has come loose yet. However, some of the screws might loosen over time since I'm moving the boxes around. Would this cause torsion issues?

Teleman

AxonSpark Have you tried switching K_Ceptors around into alternate positions? Is it just the knees or specifically those K_Ceptors? I've gotten some very strange poses by inadvertently mixing up channels and/or pins. ;-)

I had head nodding issues at first -- i.e. the head would nod forward instead of backward. That was fixed by facing South during Blender calibration. Also, the hands were drifting without the performer moving -- we had to recalibrate all the sensors. After calibrating, each sensor was reviewed in Blender -- some still had a little imperfect drift or alignment, but would slowly adjust itself to stability. We found that during K_Ceptor calibration that if we would pause a moment after each turn of the cube, giving the system a chance to stabilise after each turn, this definitely helped get rid of drift from the sensors, some more than others.

AxonSpark

Teleman Weirdly, it doesn't seem to be a K-Ceptor specific issue (at least I don't think it is). I tend to use the same K-Ceptors for the base, dorsal, and head, but I've tried switching up all of the arms and legs, and I still get this odd sideways knee bending (sometimes it's one leg, sometimes it's both).

If you're still having drift issues, I'd start with this post in the Calibration Issues threadregarding i2c baudrate and see if it helps (it solved a lot of problems I was having for months): https://forum.chordata.cc/d/63-calibration-issues/80

Teleman

AxonSpark What if you stand on a chair during Blender calibration?

daylanKifky

@AxonSpark , @Teleman let's move all the "knee bending" discussion to the thread I created specifically for that argument: https://forum.chordata.cc/d/108-knee-bending-in-the-wrong-direction

This thread is supposed to be used to announcements and feedback about the new blender addon.

Please port all the important messages there, I will remove all these last messages from this thread when we have new announcements about the addon.

HalloweenBob

daylanKifky Thank you!! I will be looking into this!

zaanen

maybe an instruction how to connect it to something like for example blenders character rain
https://cloud.blender.org/p/characters/5f04a68bb5f1a2612f7b29da
because it is already rigged. what is best approach.

daylanKifky

Hi zaanen
That's indeed a great suggestion. We should definitively make a tutorial about that.
As a general methodology the quickest way to connect with an already rigged character with the complexity of RAIN (she includes several controllers which are handled by scripts and drivers) would be to:

Edit the base chordata armature to match RAIN's body proportions.
Select FK control on the RAIN character and parent each deform bone to the equivalent in the Chordata armature.

As always with rigging the process might require some tweaking, but it should give you a moving character with not much effort.

We plan to offer direct integrations with blender rigging systems in the future. We are already in contact with Juan Pablo Bouza the creator of BlenRig discussing the best approach to it

zaanen

daylanKifky A great to hear that.

I think the whole thing i want to do with TVZ badminton will give me some headaches but in the end if all succeed it will be great to see that badminton player move on court.

daylanKifky

Hi everyone,

We are releasing an alpha version of the addon which implements the new pose-calibration algorithm among other minor changes.

You can download it from the button in the repository's README or directly from this link

In order to use it you will need the new avatar, which is currently not included in the addon. Just install the addon and open this blend file.

We renamed some of the bones in the avatar to make them more descriptive. For example the *-thight nodes become *-upperleg and so on. You will need to run the notochord with this XML file in order to assign the correct names to the nodes.

The new pose-calibration procedure is a functional one, meaning that the performer has to make some movements which are used to obtain a more accurate calibration. The final sequence of movements is still subject to changes while we finish the development of this algorithm. For the moment I made a quick video explaining the current sequence of movements to be done.

If you find any issues with the new calibration please open a new thread to report them. Once the calibration is complete the addon will generate a few files which contain debug information about the recently performed calibration. Please include them in your report. They are created in the directory where the blend file is saved and are called:

Chordata_calib_dump.csv
Chordata_calib_data.json
calibration_result.log

(some of them might be too big the upload them here, please use an external storage and link in your post)

If you can make a video of the performer + screencapture while you do the calibration it will also greatly help to debug any problem.

And last but not least: For this calibration procedure, as well as in any other mocap calibration process, a minimum two persons are required. One should wear the suit and do the movements (we normally call this person: the performer) and the other manage the capture from the PC. We might add timer functionalities in the future to the addon in order to allow users to do solo-calibrations, but they will never be as accurate as the regular way, particularly with this functional sequence which is substantially more complex than the static one.

Of course an improved static calibration will be available in the final release of this version, but for the time being we are making this alpha release to test the functional one and collect feedback to improve the algorithm and evetually correct issues.

Let us know how it goes!

daylanKifky

For those of you trying the addon and new calibration: @cubesky has a log where he documents the process . Take a look there if you have any problem, in particular I forgot to mention:

the notochord should be executed with the --raw flag in order to use the new calibration
the new calibration requires some dependencies. They should be installed automatically the first time you init a mocap session. If you are using the file I uploaded the session is already initialized so you won't go though the deps installation process. Please do Window > Chordata > Init Chordata mocap session and run the deps installation before capturing.

DigitalStages

Hi!
I started working with the Blender addon and recognized something that is not super important for functionality. However, it caused some confusion and I needed to constraint things a bit up-side down.
The addon avatar has its forearm before the arm. Cheers!
https://en.wikipedia.org/wiki/Forearm

daylanKifky

Hello DigitalStages!
thanks for pointing this out, there was some confusion with the arm parts in the previous version of the avata, but now we changed the naming convention to use

[lr]-upperarm
[lr]-lowerrarm
[lr]-hand

Pablo

Hi everyone. I'm getting an error when trying to connect the Notochord node.
Initially it says it will install some dependencies, but after that there's an error from base.py, engine.py, armature.py armature_manager.py
"chordata.defaults.Calibration_error: Dependencies not found"
location: <unknown location>:-1

I'm not so familiar with Blender coming from 3dstudio. Is there a path where I can copy files manually? How can I solve this?
Thanks

zaanen

Pablo is this when installing the dependencies?
I found that i needed to be connected to the internet and the notochord to install correctly.
So i connected a wire to the notebook and the wifi to the notochord.
Then it installed the dependencies.

After that i got an error when calibrating but the fix there was an update on http://notochord.wlan (update all)
the raspberry needs to be connected to the internet for that.

the last part with help from chordata to analyse it ofcourse.

Pablo

zaanen That was it, thank you!

daylanKifky

Hi! let's follow this issue here:

https://forum.chordata.cc/d/579-cannot-complete-installation-of-blender/2

by the way, thanks a lot @zaanen for your many interventions in this forum. We encourage people on our community to help each other as you are doing. I'm giving your the contributor badge 👍️👍️

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