Directional blur

[malkazoid]

Hello!

The current motion blur filter is great, but it blurs both into the 'past' and 'future' position of the blurred object. In other words the effect is centred on the current pixels, and extends them in BOTH directions along the axis chosen.

Directional blur is where the chosen direction causes blur along that vector and only that vector (not also its opposite).

This is highly desirable in some situations, and I'd love to see it in a future version.

In a way, the current tool is misleading because the "rotation" depicts in the UI a vector that swings 360 degrees, leading one to believe one is indicating the 2d vector for the blur. In reality the setting defines an axis... for instance settings 156 and 336 will produce the exact same result.

 

 

[NotMyFault]

I don’t know how a directional blur is exactly defined. 
never the less I assume that y or can create this effect in Affinity using vector Masks, to limit how far the blur reaches to one side. 
 

below 3 versions:

1. original
2. motion blur on car, masked to affect only right side
3. added copy of car to create a sharp front edge, too. Gives a jump start / lengthening effect

 

[malkazoid]

Thanks @NotMyFault - I appreciate the response and good to know this is a way to achieve it.

I do hope the devs consider adding a Directional Blur filter though - it would be great not to have to create a mask to remove blur, and have an out of the box way of getting it in just one direction. I'd consider this a hack for this purpose: a powerful technique but a workaround nonetheless.

[NotMyFault]

Can you provide an example of this effect? Searching the web seems to use directional and motion blur as two interchangeable  terms for essentially the same function.

There is no „inherent“ non-ambiguous definition on how  directional blur should work.

[malkazoid]

3 hours ago, NotMyFault said:

Can you provide an example of this effect? Searching the web seems to use directional and motion blur as two interchangeable  terms for essentially the same function.

There is no „inherent“ non-ambiguous definition on how  directional blur should work.

Hello!  I think maybe I expressed it poorly.

Perhaps rather than thinking of it as a separate tool, it would make more sense to think about it as the same tool, with extra control.  Right now the blur is centred on the original pixels and extends both directions along the chosen axis. It would be amazing if there was a slider in the UI, ranging from -1, to 1, default position 0 (representing current behaviour), which when slid towards -1, gradually shifts the range of the blur more and more biased towards being in one direction only... until finally at -1, the blur only extends one way, away from the original pixels. Conversely, sliding towards 1 results in blur only in the other direction.

In the 3d world, we often use the terms past and future blur, because computing the blur can be centred on the current position and extending into past and future positions, or it can be biased towards the past (blur only behind the object along its path), or future (blur only ahead of the object). 

I hope this makes sense.

 

[NotMyFault]

Thank you for additional information.

i still don’t know how the effect should be rendered. One option would be like outer shadow, which already allows these parameters:

1. extract the object to be blurred (assuming only a selection should get blurred)
2. move the object into the direction (left / right) 
3. apply motion blur. 

 

the crucial points I still miss in your description is

• where the blur should start. Center of canvas?
• Or a position to be chosen by user, similar to to radial blur?
• Hard cut or soft symmetric blur?