Kinect2 - Projector Calibration

…and markus
please let me know what I can do in addition.
I am very much interested in getting this going in
my environment.
knut

Hi Knut,

and I suspect no dmp file created?
Maybe we can trace the error with this script:

import numpy as np
import cv2

# capture a TOP into a numpyArray
img = op('camColor').numpyArray()*255

# remove the alpha channel
img = img[:,:,:3]

# convert to 8 bit
img = img.astype(np.uint8)

# convert to gray scale
gray = cv2.cvtColor(img, cv2.COLOR_RGB2GRAY)

# find corners
ret, corners = cv2.findChessboardCorners(gray, (gridResX, gridResY), None)

If this closes TouchDesigner, we should comment out lines starting from the bottom.
If it runs we can go further and check if the cornerSubPix or calibrateCamera functions are causing this behavior.

Best
Markus

so you want me to put this in a text dat and then execute
that text dat…correct?

no dmp file created…I searched for touchdesigner99*

yup, if you could create a TOP (can be a constant TOP) and call it camColor and then paste the script into a Text DAT and run it.

any chance of a more interactive session within the next hour?
it’s a 30 min drive for me back to the office.
otherwise I would do it tomorrow morning.

Awesome!

I found a problem using the checkerboard.
Green dots appear only on the left side of the screen.

Is there a way to fix it?

Thank you.

Hey,

Just wondering if this is in Non-Commercial?
If so, can you try reducing your projector resolution to 1280x720.
Can’t test it right now so mainly guessing…

Cheers
Markus

Yes I am using non-commercial tools.
Even though resolution is reduced, it does not match exactly.

Thank you so much for releasing this. I have been trying to figure out a better way then importing the calibration from RoomAlive for a while now. This is a much cleaner solution.

Hey,

I posted an updated version (viewtopic.php?f=22&t=12895#p49372) that fixes the issue with offset grid points when running the kinect at a lower resolution (mainly when trying this with the Non-Commercial version.)

The issue was that I had a fixed offset and orthographic camera width that assumed a camera resolution of 1920x1080.

Cheers
Markus

PERFECT! THERE IT IS! I WILL TRY IT LATER!

THX

Hi Markus
during the last week I did a lot of calibrations on differernt locations using your .tox.
Everything worked fine: It is stable, the results are reproducible, the UI is good.
Thnx a lot, great job!
I use this camera for the kinect directly but also for the vive tracker as an alternative to
camschnappr, if I dont have a 3D model of the object.

I will now invest some time to understand what needs to be done in order to get the best results possible by using this checkerboard approach with the kinect.
The quality of the results is today not easy judge, because this can only be done by projecting
the skeleton on a person and then visually inspecting the image (as far as I know).
I would expect that there is somewhere inside opencv some kind of value, that describes the quality or preciseness of the parameter estimation.
Is this true ? Do you plan to make this value availabale through the UI?
Could you give a starting point if I would like to do that on my own ?
thnx for your help
knut

Hi Knut,

the calibrateCamera returns a value that should indicate how precise it is.
If you go to the DAT called Calibrate, find the function of the same name:

[code]
def Calibrate(self):
fov = 180
pWidth = int(op(‘monitors1’)[parent.Kinect.par.Monitor+1,‘width’])
pHeight = int(op(‘monitors1’)[parent.Kinect.par.Monitor+1,‘height’])
size = (pWidth,pHeight)
ret, mtx, dist, rvecs, tvecs = self.calibrateCamera(self.objPoints, self.imgPoints)
rot, jacob = cv2.Rodrigues(rvecs[0],None)

extrinsic = self.returnExt(rot, tvecs[0])
intrinsic = self.returnIntrinsics(mtx, size)[/code]

the “ret” should be this value, so if you add:

parent.Kinect.par.Message = 'Calibration Error: {0}'.format(ret)

it should output it to the little Message field on the parameters.

def Calibrate(self):
	fov = 180
	pWidth = int(op('monitors1')[parent.Kinect.par.Monitor+1,'width'])
	pHeight = int(op('monitors1')[parent.Kinect.par.Monitor+1,'height'])
	size = (pWidth,pHeight)
	ret, mtx, dist, rvecs, tvecs = self.calibrateCamera(self.objPoints, self.imgPoints)
	rot, jacob = cv2.Rodrigues(rvecs[0],None)

	extrinsic = self.returnExt(rot, tvecs[0])
	intrinsic = self.returnIntrinsics(mtx, size)

	parent.Kinect.par.Message = 'Calibration Error: {0}'.format(ret)

Will add this in to a later release!

HI Markus
thnx. That just works. I will now play around for while to find out what this error means in
my environment and if this number allows me to find precise results faster…something
like a criterion to stop calibration, a little more accurate then your advice to collect something like 10-12 point pairs.
Greetings knut

I’m a little newer at TD. THis is amazing and I was able to accurately sync the skeleton to myself in real time. I guess my question is - how do I transmit this data into other work?

Would someone be able to create a very simple file that creates a circle TOP and then uses this projector calibration tox to align it to the right hand? I was able to successfully use it but wasn’t sure how to integrate it. Thanks so much!

Hey,

there is a skeleton inside the network. Go to kinectCalibration/projectorView: There you will see a kinect CHOP called kinect1 which reads all the channels from a skeleton. Theoretically you can just select out the wrist channel and use the same network to do what you want. Optionally also just copy that section out into your own scene.

Best Markus

Thank you for your reply! Do you mean, copy the section from kinect1 to null2?

I don’t know if you had a moment where you might be able to create a very quick file with this - maybe map the bannana to the right hand so after the calibration is complete, the bannana is following the hand? Just so I could reference and learn from it. I would super appreciate it if you could help with that.

If not, totally cool and I appreciate that this exists. Just trying to connect the dots that I’m missing to apply it properly.

Or what I mean to ask. Once it’s calibrated, you had said that it works as a camera. I was just wondering how to integrate it as such. I was assuming it would be able to track and put on my hands and it would keep it accurately on my hand even if I move on the z axis a little bit?

If you happen to have an example of it being used in such a way, or any example files that demonstrate using this tox file, it would really be helpful as I could analyze it! Thanks so much!

Posted a crucial fix where for builds 2018.27550 and upwards the resulting matrix had rows and columns switched creating a bad calibration result.

You can download the latest version from here: viewtopic.php?f=22&t=12895&p=49372#p49372

Best
Markus