[Camino-users] Runge-Kutta error message in the Track command (r1218)

[Philip A Cook]

Hi again,

I traced the problem - it's not the edge of the image, it's that the intermediate steps the RK4 tracker takes can enter background regions. This should be fixed in r1219.


On Jul 22, 2013, at 4:38 PM, Yan Jin wrote:

> Hi,
> 
> I have downloaded a few DTI dataset from ADNI. I would like to use Runge-Kutta method (rk4) to track the fibers. But I got errors when the tensor data were interpolated. However, this didn't happen when I used the "euler" option, even the same interpolation method was used. Here is the error message:
> 
> "Processing ROI 1 of 1
> Processing seed 1 of 61660Exception in thread "main" java.lang.NullPointerException
>         at tractography.EightNeighbourLinearInterpolator.interpolateVectorElements(EightNeighbourLinearInterpolator.java:80)
>         at tractography.VectorLinearInterpolator.getTrackingDirection(VectorLinearInterpolator.java:87)
>         at tractography.RK4FibreTracker.getNextStep(RK4FibreTracker.java:94)
>         at tractography.RK4FibreTracker.getFirstStep(RK4FibreTracker.java:56)
>         at tractography.FibreTracker.trackFromSeed(FibreTracker.java:303)
>         at tractography.FibreTracker.trackFromSeed(FibreTracker.java:230)
>         at apps.StreamlineTractography.execute(StreamlineTractography.java:946)
>         at apps.EntryPoint.main(EntryPoint.java:284)"
> 
> The commands I used:
> 1. image2voxel -4dimage adni.nii.gz  -outputfile adni.Bfloat
> 2. dtfit  adni.Bfloat adni.scheme -bgmask adni_brain_mask.nii.gz >adni_dwi.Bdouble
> 3. track -inputfile adni_dwi.Bdouble -inputmodel dt -seedfile adni_seed.nii -curvethresh 40 -anisthresh 0.2 -anisfile adni_FA.nii -tracker rk4 -interpolator linear -stepsize 1>adni_rk4_tract.Bfloat
> 
> Have you used the "rk4" option and encountered the same error?
> 
> Thanks,
> Yan
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