Questions on format of the raw kinect correlations

[schellmi42]

Hello,

I downloaded the data from the google drive link given in another issue #11 , but now I had some problems loading the measurements and understanding which of the nine measurements is for which frequency at which phase offset.

First, I loaded the raw kinect correlations as described using the given code:

with open(filename,'rb') as f:
	meas=np.fromfile(f, dtype=np.int32)
meas = np.reshape(meas,(424,512,9)).astype(np.float32)

However the correlations are not correct and looked like this: (small snippet of one image)

[[-54. -51. -50. -68. -55. -59. -57. -46. -47. -50.]
 [ 45.  39.  45.  60.  45.  55.  49.  52.  54.  60.]
 [-47. -51. -51. -49. -52. -54. -48. -47. -57. -66.]
 [ 49.  48.  49.  62.  48.  46.  41.  41.  48.  39.]
 [-50. -53. -55. -52. -36. -54. -50. -53. -40. -48.]
 [ 56.  45.  52.  53.  50.  65.  54.  49.  41.  47.]
 [-37. -50. -48. -50. -57. -50. -50. -51. -53. -42.]
 [ 56.  50.  56.  48.  45.  49.  46.  52.  43.  44.]
 [-50. -50. -54. -57. -57. -54. -42. -37. -50. -52.]
 [ 67.  54.  42.  43.  56.  45.  51.  45.  50.  43.]
 [-54. -40. -53. -42. -41. -41. -47. -48. -53. -49.]
 [ 50.  48.  43.  44.  46.  51.  57.  45.  32.  34.]
 [-47. -60. -41. -37. -48. -42. -48. -43. -45. -45.]
 [ 47.  49.  44.  40.  43.  46.  44.  48.  50.  44.]
 [-47. -37. -49. -52. -51. -43. -40. -46. -41. -49.]
 [ 40.  44.  57.  48.  35.  62.  34.  51.  57.  49.]
 [-52. -44. -45. -50. -44. -53. -44. -44. -40. -51.]
 [ 38.  51.  45.  40.  42.  46.  47.  44.  39.  46.]
 [-51. -51. -57. -47. -45. -49. -41. -45. -46. -42.]
 [ 39.  45.  42.  42.  51.  42.  48.  46.  37.  38.]]

Every other line seems to have the wrong sign.

To get something that looks like the image in the paper I used this transformation:

sign_fix = np.concatenate(
    (np.tile([1, -1], shape[0] // 4), np.tile([-1, 1], shape[0] // 4)), axis=0
                            ).reshape([ -1, 1, 1])

  meas= meas* sign_fix

Could you verify whether this is the right thing to do, or how to transform the data correctly?

Also could you provide the frequencies and phase_offsets for the measurements?
I was not able to find them in the paper or the supplementary.

So far I think the first 3 are at 40MHz(T=2.5e-8s) and the last three at ~58MHz (T=1.7e-8s) .
(taken from sim/tof_class/cam_real_mult)
But the middle one (low frequency signal) I did not find the frequency in the your code.

The phase offsets I figured should be [240, 120, 0]. Is this correct?

I tried with [0, 120, 240] first, but then the ToF-depth reconstruction is off and decreases with object distance.

I would be happy if you could help matching frequency, / phase_offsets to the data.

Thanks and best regards,