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The LTA Transform Format

WORK IN PROGRESS

LTA means Linear Transform Array. The .lta format is from subject ras to talairach ras, and stores affine. It is generic enough that it will list what type of transform it is (e.g. voxel or ras). Here are most of the relevant types:

#define LINEAR_VOX_TO_VOX       0
#define LINEAR_VOXEL_TO_VOXEL   LINEAR_VOX_TO_VOX
#define LINEAR_RAS_TO_RAS       1
#define LINEAR_PHYSVOX_TO_PHYSVOX 2
#define TRANSFORM_ARRAY_TYPE    10
#define MORPH_3D_TYPE           11
#define MNI_TRANSFORM_TYPE      12
#define MATLAB_ASCII_TYPE       13
#define LINEAR_CORONAL_RAS_TO_CORONAL_RAS       21
#define LINEAR_COR_TO_COR       LINEAR_CORONAL_RAS_TO_CORONAL_RAS

A sample .lta files looks like following

type      = 0
nxforms   = 1
mean      = 127.000 125.000 115.000
sigma     = 10000.000
1 4 4
+1.141600  +0.018630  +0.010876  -23.066311                                         
-0.019849  +1.142709  +0.150979  -29.566288                                         
-0.010058  -0.155729  +0.919673  +26.393215                                         
+0.000000  +0.000000  +0.000000  +1.000000                                          
src volume info                                                                     
valid = 1  # volume info valid
filename = /tmp/bert/mri/nu.mgz
volume = 256 256 256
voxelsize = 1.0000 1.0000 1.0000
xras   = -1.0000 0.0000 0.0000                                                      
yras   = 0.0000 0.0000 -1.0000
zras   = 0.0000 1.0000 0.0000
cras   = 5.3997 18.0000 0.0000                                                      
dst volume info
valid = 1  # volume info valid
filename = /usr/local/freesurfer/stable/average/RB_all_2007-08-08.gca               
volume = 256 256 256                                                                
voxelsize = 1.0000 1.0000 1.0000                                                    
xras   = -1.0000 0.0000 0.0000                                                      
yras   = 0.0000 0.0000 -1.0000
zras   = 0.0000 1.0000 0.0000
cras   = 0.0000 0.0000 0.0000      

FsTutorial/LtaFormat (last edited 2008-11-26 02:30:51 by KrishSubramaniam)