P: Motion blur to follow a path or shape

Forum|Forum|14 years ago
October 12, 2011
23 replies
820 views

This is something especially important in automotive retouching.
Anybody who ever tried to replicate a motion blur taken in-camera knows this problem:
The blur in camera starts out thin and then fans out... almost impossible to replicate, right? Or worse... in a rig shot, it follows the curve of the road...ick!
How about these two options:
You start by drawing a path with your pen tool and then the motion blur gives you the option to select "follow path" and will curve your blur to match your drawing.
Same applies for drawing a shape. Use your pen tool to draw a rough outline of your curved street and the motion blur gets calculated to follow the movement and fanning-out of the shape.

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FeedbackCommunityMember

Inspiring

A mask or depth map only helps one small part. You still need color values for things that are hidden (which you don't have). It's rather easy to come up with something wrong, but takes a bit of thought to get something even close to right.

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tommythirteen

Participating Frequently

occlusion is not a problem for professionals. you just paint a quick depth mask.
i`m working on car campaigns most of the time and nearly all of them need this type of motion blurring done. virtual rig works and is easy. but it`s not perfect. with gradient implementation to control the strength it would be.

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FeedbackCommunityMember

Inspiring

Reasonable motion blur for the foreground object or the background is the same problem, with different masks or depths.

It's not an easy problem to solve.

Pierre's idea (see below) about a motion blur layer style helps some of the occlusion problems, but adds other UI complexities.

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FeedbackCommunityMember

Inspiring

Funny, it took me 30 minutes to write my first Photoshop plugin in 1990. (and I've written several hundred of them since)

And correctly blurring along a path is much harder to get right than you think because of occlusion (foreground blocks background). It's easier to do in a 3D program because you have the additional depth/motion information.

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tommythirteen

Participating Frequently

it`s unbelievable that the code for this was written in less than 2 hours by a friend of mine... but to build a photoshop plugin out of that took a week before we gave up trying to make this work inside of PS. I'm not a programmer but that seemed strange to me. i heard there are hundreds of lines of dead code in photoshop... maybe thats why.

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tommythirteen

Participating Frequently

it`s not for the moving object - the camera moves with the object, so its the only thing sharp. the background needs the motion blurring.

a friend of mine programmed a tool for this in less than 2 hours. it has no interface yet, so i have to use the console though :))) but it`s ultra-fast even on hi-res data.

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FeedbackCommunityMember

Inspiring

i want to align motion blur to a path to be able to:

*simulate rigged car shots.
*clean curvy objects easily.
*...

kinda like in virtual rig:
http://www.virtualrig-studio.com/

you should then add the ability to control the strength via an alpha channel with gradients.

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FeedbackCommunityMember

Inspiring

It would be great if PS implemented VECTOR BLURRING. ie: Curved motion blur. There are other stand-alone programs that do it, but cost a fortune. See: http://www.virtualrig-studio.com/ for an example of what a simple 10mb program can do, but costs the earth. PLEASE bring vector blurring to the next PS! Even if it is as a plugin or *something*. I know I'm not the only automotive photographer who would like to see this addition.

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xajideAuthor

Participating Frequently

Doesn't really do what I need it to do.... in my usual workflow, I mostly use gaussian and motion blur. Lensblur can be nice but sucks up so much ram that I only use it if gaussian just won't cut it for the look.