Bluring a path

[PixLab]

It's just a case study... let's call it Linear Motion Blur along a Path (with Perspective)
I saw this PS tuto > https://youtu.be/cL1BvOtd5zY?t=333 and told myself "let's do it with GIMP"

Below is what I came with at best I can think of (I did tried with partial selections and linear motion blur, but it's quite cumbersome, I'm searching something more straightforward like the paths),
If you want to try:
Photo: https://www.pexels.com/photo/photo-of-ca...d-3182452/

Smudge tool Brush: 2. Block 01 > @90 degrees > Dynamics > Track direction

Edit > Stroke path with the smudge tool
anyway it's all in the screenshot

   

But I am not truly satisfied for multiple reasons, as you can see on the "coupole/dome" the blur is fragmented and it's not a true linear motion blur, also the brush keep the same size which lead to some "blank" between paths that I need to fill with secondary paths (the shorter ones), overall it's not clean...
I think the best solution would be to do a "Linear Motion blur along the Path" where the size is increasing as it goes toward the end of a path, ( you might have better idea, if so please feel free )
In the end,  I would like to know if it's possible to do a linear motion blur along a path, in a way or in another way... if so how? any idea? or is it possible to have a Linear Motion blur between 2 Paths?

What do you think? Am I on the wrong path?  

[denzjos]

You can use : Filters / Blur / Zoom Motion Blur. Make the canvas wider and set the photo on the right side. Then put the centre X in the extended canvas.  
   

[Ofnuts]

No need to enlarge the canvas in many cases. You can actual drag the controls outside the canvas (even if they are no longer visible), and the sliders will go negative or over 1, and in the dire cases you can enter the value by hand, too.

[PixLab]

(06-21-2021, 07:50 AM)denzjos Wrote: You can use : Filters / Blur / Zoom Motion Blur. Make the canvas wider and set the photo on the right side. Then put the centre X in the extended canvas.  

I've always thought that this filter was just a "gadget" -> I was on the wrong path    it's even better than I would ever thought, excellent idea, and it's so clean, quick, and easy! Thanks a lot!

(06-21-2021, 09:25 AM)Ofnuts Wrote: No need to enlarge the canvas in many cases. You can actual drag the controls outside the canvas (even if they are no longer visible), and the sliders will go negative or over 1,  and in the dire cases you can enter the value by hand, too.

Indeed, also I can see the controllers on the canvas outside, Thank you.
I think I understood why denzjos tell us to enlarge the canvas you will have a more clean effect on the very side as the effect will continue to go after or before the image depending the blurring factor, which make the effect cleaner
below without enlarging the canvas (enlarging the canvas see denzjos post)