[MINC-development] Grid transforms

[Vladimir S. FONOV]

Try specifying -image_range 0 1 -valid_range 0 1 in mincreshape

On Dec 21, 2016 8:47 PM, "Andrew Janke" <a.janke at gmail.com> wrote:

> Hi all,
>
> I understand that a while back the precision of grid transforms went
> from short to double. This was probably around the -50 -> + 50
> wierdness that used to happen within minctracc.  Perhaps there were
> also other rationales.
>
> Were there also other changes to libminc/volume_io to support this? I
> ask as I'm getting wierdness with xfmconcat when I feed in a zero grid
> transform.  ie:
>
> mincresample -xstep 32 -ystep 32 -zstep 32 \
>    -xnelements 10 -ynelements 10 -znelements 10 \
>    /opt/minc/share/icbm152_model_09c/mni_icbm152_t1_tal_nlin_sym_09c.mnc
> /tmp/like.mnc
>
> minclookup -signed -short -lut_string '0 0 0 0;1 0 0 0'  /tmp/like.mnc
> /tmp/like_vector.mnc
>
> mincreshape -dimorder vector_dimension,zspace,yspace,xspace \
>    /tmp/like_vector.mnc /tmp/zero_grid_0.mnc
>
> echo "MNI Transform File" > /tmp/zero.xfm
> echo "Transform_Type = Grid_Transform;" >> /tmp/zero.xfm
> echo "Displacement_Volume = zero_grid_0.mnc;" >> /tmp/zero.xfm
>
> xfmconcat /tmp/zero.xfm /tmp/z.xfm
>
> mincstats /tmp/z.xfm
>
> cai-zeep:tmp$ mincstats z_grid_0.mnc
> *** mincstats - reported max (-32768) doesn't equal header (32767)
> File:              z_grid_0.mnc
> Mask file:         (null)
> Total voxels:      3000
> # voxels:          3000
> % of total:        100
> Volume (mm3):      98304000
> Min:               -32768
> Max:               -32768
>
> Note the messed up min and max. This will work however if you make an
> unsigned short volume at the minclookup stage.   If I then use this
> transform things of course go awry instead of it being a zero xfm.
>
> So, is this defined or unexpected behaviour? If I use a double, I get
> a more interesting error instead of a failure.
>
> xfmconcat ident-32.xfm /tmp/d.xfm
> Volume has invalid min and max voxel value
>
>
> ta
>
>
> a
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