If two images have different image headers, they are supposed to align in the physical space, not in the image voxel space, for warping in ANTS.

I noticed you used two different images as references. Could you try both use "-R epi_template.nii.gz" and verify if this issue still exists?

Also, are these image real 4D image or just 3D? If they are 3D, you can try use WarpImageMultiTransform instead with the same syntax.



-Gang




Quoting Yaroslav Halchenko <[email protected]>:

Package: ants
Version: 1.9+svn532-3
Severity: normal

P.S. CCing all possibly interested parties ;)

According to docstring of WarpTimeSeriesImageMultiTransform sequence of
necessary transformations could be arbitrarily long. Having applied a sequence

MNI -> inverse warp -> inverse affine -> inverse affine

produces different (and looks like incorrect) result from if I do transformations in two steps, e.g.

MNI -> inverse warp -> inverse affine

and then result of previous given for the final inverse affine.

Here is output of running reproduce.sh.  All data, script and
results are available from

http://www.onerussian.com/Linux/bugs/ants.2steps/

I investigate the result by comparing mni2bold.nii.gz  and mni2bold-2.nii.gz
overlayed on top of epi_template.nii.gz. mni2bold.nii.gz seems to be offset
toward anterior

$> ./reproduce.sh
I: Lets do directly all the steps at once
Running: WarpTimeSeriesImageMultiTransform 4 mni.nii.gz mni2bold.nii.gz -R epi_template.nii.gz anat2mni_InverseWarp.nii.gz -i anat2mni_Affine.txt -i raiders_func2anat_Affine.txt --use-NN
FIELD: anat2mni_InverseWarp.nii.gz
AFFINE-INV: anat2mni_Affine.txt
AFFINE-INV: raiders_func2anat_Affine.txt
moving_image_filename: mni.nii.gz
output_image_filename: mni2bold.nii.gz
reference_image_filename: epi_template.nii.gz
[0/3]: FIELD: anat2mni_InverseWarp.nii.gz
[1/3]: AFFINE-INV: anat2mni_Affine.txt
[2/3]: AFFINE-INV: raiders_func2anat_Affine.txt
 Four-D image size: [182, 218, 182, 1]
 4D-In-Spc [1, 1, 1, 1]
 4D-In-Org [-90, 126, -72, 0]
 4D-In-Size [182, 218, 182, 1]
 4D-In-Dir 1 0 0 0
0 -1 0 0
0 0 1 0
0 0 0 1

 ......
 4D-Out-Spc [3, 3, 3, 1]
 4D-Out-Org [-70.5, -75.759, 93.1085, 0]
 4D-Out-Size [64, 64, 48, 1]
 4D-Out-Dir -0 0 1 0
1 -0 0 0
0 -1 -0 0
0 0 0 1

 Use Nearest Neighbor interpolation
0 % done ... -0 0 1
1 -0 0
0 -1 -0

 100 % complete
I: Lets do directly all the steps at once
Step 1 mni->anat: WarpTimeSeriesImageMultiTransform 4 mni.nii.gz mni2anat.nii.gz -R brain_avg.nii.gz anat2mni_InverseWarp.nii.gz -i anat2mni_Affine.txt --use-NN
FIELD: anat2mni_InverseWarp.nii.gz
AFFINE-INV: anat2mni_Affine.txt
moving_image_filename: mni.nii.gz
output_image_filename: mni2anat.nii.gz
reference_image_filename: brain_avg.nii.gz
[0/2]: FIELD: anat2mni_InverseWarp.nii.gz
[1/2]: AFFINE-INV: anat2mni_Affine.txt
 Four-D image size: [182, 218, 182, 1]
 4D-In-Spc [1, 1, 1, 1]
 4D-In-Org [-90, 126, -72, 0]
 4D-In-Size [182, 218, 182, 1]
 4D-In-Dir 1 0 0 0
0 -1 0 0
0 0 1 0
0 0 0 1

 ......
 4D-Out-Spc [1, 1, 1, 1]
 4D-Out-Org [-86.8253, -128, 132.723, 0]
 4D-Out-Size [256, 256, 176, 1]
 4D-Out-Dir -0 0 1 0
1 -0 0 0
0 -1 -0 0
0 0 0 1

 Use Nearest Neighbor interpolation
0 % done ... -0 0 1
1 -0 0
0 -1 -0

 100 % complete
Step 2 anat->mni: WarpTimeSeriesImageMultiTransform 4 mni2anat.nii.gz mni2bold-2.nii.gz -R epi_template.nii.gz -i raiders_func2anat_Affine.txt --use-NN
AFFINE-INV: raiders_func2anat_Affine.txt
moving_image_filename: mni2anat.nii.gz
output_image_filename: mni2bold-2.nii.gz
reference_image_filename: epi_template.nii.gz
[0/1]: AFFINE-INV: raiders_func2anat_Affine.txt
 Four-D image size: [256, 256, 176, 1]
 4D-In-Spc [1, 1, 1, 1]
 4D-In-Org [-86.8253, -128, 132.723, 0]
 4D-In-Size [256, 256, 176, 1]
 4D-In-Dir -0 0 1 0
1 -0 0 0
0 -1 -0 0
0 0 0 1

 ......
 4D-Out-Spc [3, 3, 3, 1]
 4D-Out-Org [-70.5, -75.759, 93.1085, 0]
 4D-Out-Size [64, 64, 48, 1]
 4D-Out-Dir -0 0 1 0
1 -0 0 0
0 -1 -0 0
0 0 0 1




-- System Information:
Debian Release: squeeze/sid
  APT prefers unstable
  APT policy: (901, 'unstable'), (900, 'testing'), (300, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.32-5-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_US, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages ants depends on:
ii libc6 2.11.2-2 Embedded GNU C Library: Shared lib
ii  libgcc1                      1:4.4.4-6   GCC support library
ii libinsighttoolkit3.18 3.18.0-3+b1 Image processing toolkit for regis
ii  libstdc++6                   4.4.4-6     The GNU Standard C++ Library v3

ants recommends no packages.

Versions of packages ants suggests:
ii fsl 4.1.6-1 analysis tools for FMRI, MRI and D
pn  gridengine-client             <none>     (no description available)

-- no debconf information

--
                                  .-.
=------------------------------   /v\  ----------------------------=
Keep in touch                    // \\     (yoh@|www.)onerussian.com
Yaroslav Halchenko              /(   )\               ICQ#: 60653192
                   Linux User    ^^-^^    [175555]










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