Hi Enedino, 

Thank you for your question. You can build the colors that you want. Just create a 2D array with as many RGB values as the number of points
of the streamlines and provide that array as a parameter in actor.line.

Have in mind that there is no right or wrong way to color streamlines. Every software has different preferences.
We use the average orientation around the middle point of the streamline to color it. However, we do provide ways for people to
build their own colors as explained above.

Let us know how you progress. Be happy to use DIPY's chatroom at https://gitter.im/dipy/dipy to post your code solution.
You can get faster feedback there because FURY's bundle visualization is used primarily in DIPY.

Best regards,
Eleftherios



On Thu, Sep 2, 2021 at 10:27 PM Nino <ninoht@drcmr.dk> wrote:
To whom it may concern.

My name is Enedino Hernández and I am working at the DRCMR in Copenhaguen K on a quality assurance of fibre tracts in my DTI analysis.
I have a question regarding the colouring of the tracts using fury. In your documentation (snapshot attached) it is mentioned that it is possible to create a streamline with orientation colouring. However, in the example the streamlines pointing upwards should change color, I would expect a combination of blue and green, instead of only green. I would expect similarly a change in colour for the fibres curbing in downwards direction.
Is there a way to use the local orientation of the fibre elements to produce the correct local orientation colouring?

Thank you very much in advance for your attention.
With kind regards,
Enedino Hernández, PhD