[MINC-development] minctracc error

[Anthonin Reilhac]

Hello,

I am currently experiencing issues with minctracc which crashes and outputs
this error:
*Error in /usr/local/bic/bin/minctracc in file init_params.c, line 593
Cannot calculate the COG or COV of volume 1.*

infos:
*a)* The two volumes I am trying to align are 2D sections (written as 3D
volumes  z->length = 1).
*Source:*
image dimensions: xspace yspace zspace
    dimension name         length         step        start
    --------------         ------         ----        -----
    xspace                   6720       0.0016       1.9464
    yspace                   8544       0.0016       6.6568
    zspace                1          0.1            0

*Target:*
dimension name         length         step        start
    --------------         ------         ----        -----
    xspace                   7520       0.0016       1.0248
    yspace                   8128       0.0016       7.3224
    zspace                      1          0.1            0


*b)* mincstats -com -world_only gives me correct COG values.
*Source*: CoM_real(x,y,z):   7.42142568 13.35683104 0
*Target*: CoM_real(x,y,z):   8.261485204 10.00648279 0

*c)* if I downsample enough both volumes (0.02 mm) using autocrop, I can get
minctracc working without crashing:
*Source:*
    dimension name         length         step        start
    --------------         ------         ----        -----
    xspace                    538         0.02       1.9464
    yspace                    684         0.02       6.6568
    zspace                      1          0.1            0

*Target:*
  dimension name         length         step        start
    --------------         ------         ----        -----
    xspace                    646         0.02       1.0248
    yspace                    748         0.02       2.9704
    zspace                      1          0.1            0

minctracc gives:
*Source*: COG of v1: 5.848002 12.464701 0.000000
*Target:* COG of v2: 11.014800 10.345677 0.000000
             [trans] = 5.166798 -2.119023 0.000000
But the COG values are not correct.
For comparison, *mincstats -com -world_only* on the downsampled volumes
gives the following values which are not different from when computed in
point b.
*Source:* CoM_real(x,y,z):   7.42070981 13.35900666 0
*Target:* CoM_real(x,y,z):   8.259952437 10.00411748 0



*d)* If I donwsample further (0.1 mm)*, *the discrepancies between the COG
values computed with mincstats & minctracc decrease slightly.
*
Source:*
    dimension name         length         step        start
    --------------         ------         ----        -----
    xspace                    108          0.1       1.9464
    yspace                    137          0.1       6.6568
    zspace                      1          0.1            0
*Target:
*   dimension name         length         step        start
    --------------         ------         ----        -----
    xspace                    130          0.1       1.0248
    yspace                    150          0.1       2.9704
    zspace                      1          0.1            0

*minctracc gives:
Source:* COG of v1: 6.783619 12.909432 0.000000
*Target:* COG of v2: 10.974800 10.455488 0.000000
   [trans] = 4.191181 -2.453944 0.000000

*
mincstats still gives the "same" values as in b) and c):*
*Source*: CoM_real(x,y,z):   7.426436221 13.35572188 0
*Target:* CoM_real(x,y,z):   8.267742651 9.998513526 0



Am I hitting at a limit of minctracc here? Any clue?

Thanks in advance.

Anthonin
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