Astra S intrinsic and extrinsic parameters

Technical Support & Q&A
1

Hi guys I did intrinsic and extrinsic calibration for Astra S (the preview version) which I assume should be very similar for all Astra S’s. Posting it here for those interested for use with OpenCV

Intrinsic IR (1280x1024):
[1162.91249825974, 0, 634.5650580131721;
0, 1158.660613757674, 514.0384586997419;
0, 0, 1]
Distortion IR:
[-0.0666383596333904, 0.1965139704345168, 4.021838721150343e-05, -0.0002282615301883382, -0.2170999600919534]
Intrinsic Video (640x480):
[509.9149156563371, 0, 336.435697832244;
0, 507.9923678046019, 245.4809047393366;
0, 0, 1]
Distortion Video:
[0.05064843449744877, -0.2746459217795117, -0.001534982398969381, 0.0009822206386673955, 0.295965667589326]
Extrinsic Video (From Video to IR):
[0.9999916078989615, -0.003887170310613853, 0.001293846446036049, 25.66748434900557;
0.003898123590546762, 0.9999556476958109, -0.008573638301445622, 0.06285861333761496;
-0.00126046186870557, 0.008578609923960567, 0.9999624086372697, -1.971187396362035;
0, 0, 0, 1]

1 Like
2

Hey zhumxcq it’s very interesting,

How did you do these calibrations? I bought a Astra S with mark 15/12/02 and I would be glad in upload my calibration data to compare it.

Thanks!

3

I just got the IR and color image from OpenNI while holding a board with chess pattern still, then ran OpenCV’s calibration routine on it. I also used a IR projector to light up the scene while covering the the Astra’s projector.

4

Hi zhumxcq,

What you have done is great and thanks for sharing these data. Could you please explain a bit on how you did the IR calibration ? I’m using ASTRA S together with MATLAB and having problems in getting accurate depth values. I have calibrated it for RGB using a checkerboard pattern but wondering how to calibrate depth sensor.

5

So Orbbec actually released a calibration tool Universal Download Thread for Astra Series Cameras that get the intrinsic & extrinsic values, you can follow their guide there!

1 Like
6

Many thanks zhumxcq. Just a small question, did you print the checkerboard on an A1 paper and captured images at 1.6, 2.0 and 2.4 m distances?

Can we survive with a A2 instead ? I have tried A3 but it seems too small.

7

Hi zhumxcq, Please ignore my above question. Thanks.

I have printed it in A1 and managed to calibrate. Below are my camera (ASTRA S) parameters.

[Left Camera Intrinsic]
553.797 0 314.796
0 553.722 265.393
0 0 1

[Right Camera Intrinsic]
493.489 0 307.503
0 493.869 248.419
0 0 1

[Right to Left Camera Rotate Matrix]
0.999998 -0.00107117 -0.00166391
0.00108444 0.999967 0.00799295
0.0016553 -0.00799474 0.999967

[Right to Left Camera Translate]
-24.7362 -0.44281 0.648089

8

That looks reasonable for calibration, thanks for posting!

9

Hi! Do you know where we can find now this calibration tool from orbbec?