How do you create a blurred motion rendering?
hrpschrd
Posts: 179
I want to depict the rotation of an object as it spins about 90 degrees in an image. I realize that I could create multiple copies of the object and make all of them more transparent than the final one but isn't there an easier and smoother way to show blurred motion in a image?
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Carrara, and most other 3D or 2D apps, has a feature called "Motion Blur" that does that for you. It generates additional, blurred images in between frames to simulate what you're describing.
Just go to the "Render" tab in Carrara and down at the bottom you enable Motion Blur.
You can also do the same thing in an app like Photoshop, or a compositing app like After Effects or a (free) compositing app like Fusion, using motion information from the "Velocity" render pass from Carrara.
Personally, I find I get much better, faster, and more flexible results doing a motion blur in a 2D compositing app rather than at render time in Carrara. Motion blur, in real life, tends to be a fairly complex effect, and you have a lot more control over your motion blur in a 2D compositing app.
But whatever works.
I'm not trying to sell 2D motion blur outside of Carrara, just mention the benefits you can obtain for those who are interested. Speed is one benefit, but there are others:
1. Realtime feedback: In a 2D blur you can generally make changes to the blur effect (how many frames, intensity, etc.) and see the results in real time. That way it's much easier to find what "looks right" in the effect for whatever purposes you have. If you have to guess, then render, then re-guess in Carrara it can be quite frustrating and time consuming. That applies to any 3D effect in just about any 3D app.
2. Flexibility: With a 2D blur you have almost infinite flexibility. You can layer effects (like add a glow to the blur or whatever your brain can come up with...). Or you can do like often occurs in the real world, which is add a camera shake to the effect. This is because a motion blur is typically the result of a long camera exposure, and if the camera is handheld during the exposure that usually means you also get a camera shake with it. In 2D you just try it, tweak it, see if you like it in real time, and if you don't then just discard it.
3. Artistic Control: For those who want artistic control, a 2D blur allows you far more direct control over the results. You can add a surrealism, for example, or exaggerate or "improve" on reality to emphasize motion or power or whatever you want. A generic motion blur may be all you need, but that may or may not be what you're looking for.
4. Saving "the Look": Once you've found a really cool blur effect in your 2D app, generally you can save the steps used in that effect and apply them later on with a different production. For example, let's say you finally dialed in an awesome glowing, zoomy, cartoony, swishy, blurry rocket ship blur effect, and you want to use that later for use with your next rocket ship renders. If you've done it in 2D it's easy to just save that off and reload it next time.
Notwithstanding the excellent advice already given, if you just want to experiment with Carrara's motion blur feature, these are the settings that I used for this image.
Each propeller/gear assembly has a rotation modifier applied @ 10 cycles/sec. The frame rate is 24 FPS. The Motion Blur settings are "Vector Blur", Extra Frames=16. Intensity=98.8%.
I advanced the timeline one frame, then rendered a still image.
It took some fiddling around before I found the settings that looked right, but maybe these settings can help as a starting point.
Something is askew with Carrara's velocity pass and for now I'm staying away from it, it does not render correctly in Fusion (maybe not enough information, some say 32bit float format works the best), not too bad but still not satisfactory, Carrara's MB is not that good either, too many frames needed for a good looking effect, for stills not bad at all, for animation it's time consuming
I do all my blurs in PS now.
But can anyone confirm one of my pet "bugs" ...Vector motion blur does not work with boned characters /objects? It used to really annoy me ...but as I dont waste any more of my time doing animation I dont really care anymore...just curious if they fixed it ....6 years later....
I've been using a product called "ReelSmart Motion Blur". Its simply a plug-in to your video editor that analyzes your video/animimation pixel by pixel, figures out whats moving where, generates motion vectors, then generates simulated but generally very appropriate motion blur for you. No Carrara sub-frame rendering needed.
I also use it on home movies shot at 24fps which can sometimes be a bit choppy/strobe-like on playback. Does the trick there too.
Hope this helps
- Don
Ok, despite all the interesting 2D options, I want to use Cararra.
Can you be more specific besides use Motion Blur?
I have used animation but I want a single image with blur from a 90 degree rotating object. Do I make the 0 deg object, copy to 90 deg and then what? Can someone take me through step by step?
Thanks.
If using Carrara, I would make a simple 2 or 3 frame animation with the object rotating as you'd like in those frames. Then, as I mentioned earlier, "Just go to the "Render" tab in Carrara and down at the bottom you enable Motion Blur.". For your purposes I would also select the output "File Format" as "movie", and select Sequenced images in whatever format you want. Then just hit render and you should get some images with a motion blur.
Then if you don't like the results, tweak the Motion Blur settings to increase/decrease the effect
I guess I don't know the right language to use. JoeMamma, you gave me 47 sequential images of the rotating object.
What I want is a single image (and file) that implies that something is rotating (kind of like the helicopter blades of de3an above). Idealy, I would like one sharp instance at each end of the rotation. I want to imply motion. I could do this by making many key frames and then make each of the intermediate frames nearly transparent.
I can't find anything about Motion Blur in the PDF help file (which has no search function). Where else would I look but here?
Using my drone I made for the Carrara Challenge this month here are the 5 steps to get a motion blur on one rotor blade for a single image.
Just play with the settings to get what you need :-)
hope this helps
same applied to the prop of this plane :-)
I'm not sure how a 2 or 3 frame animation can generate 47 sequential images....you should get only 2 or 3 at the most. And it sounds like, from Stezza's response, if you select a single frame (instead of movie) for rendering it will still calculate the blur on the single frame.
Anyway, I think Stezza's response is probably the clearest on how to do this, so I'd recommend you do his steps.
click on the thumbnails to view them larger
Also, Joe may not be aware of this, but if you scrub along the timeline to the middle or even the end, and then in the render room, select the Current Frame option, Carrara will render a still image of that frame. If you are using the Motion Blur option, Carrara will still render the additional frames that you set in the Motion Blur controls and composite them as part of a post render process. The amount the image is blurred will depend on the blending level and the number of frames you want to generate the blur. No image sequence is needed.
Although, to be technical, that is exactly what Carrara is doing for you. It is rendering a sequence of images leading up to the rendered frame and then it composites them together, adds the blending level you chose (default is 90% which seems high) and outputs a single frame. I'm not sure if the vector motion blur in Carrara Pro uses an internal velocity pass, like what you would get if you choose to render one out for yourself. I haven't compared the standard motion blur against the vector blur for quality or speed advantages.
I'm not sure about the specifics of Carrara's blur cuz I almost never use it, but generally with motion blur effects there's the simple "blur the object only" blur effect, and the more complicated, "blur the object and reflections and shadows and everything associated with it" blur.
So I assume the velocity pass in Carrara only shows velocity of the object itself for use in a blur effect. Not the shadows and reflections and such. I'm not sure if the internal Carrara blur is the more complicated blur or not.
Maybe someone can do some research and find out what the real deal is.
Thanks especially to Stezza, I was able to get a quick blur done.
It is not quite what I expected however and I am puzzled by result. As you can see I was trying to blur the rotation of part of a molecule. Since the rotation is 360 degrees I expected a curved blur rather than this straight one. The length of the blur was dependent on carefully adjusting the spin rate (I think dependent on the frame rate). So why is the blur straight?
Hi hrpschrd, I just tried a simple set-up with a Sphere offset from and parented to a Target Helper and I get a motion blur trail in an arc.
The Target Helper has a Spin Modifier set to spin for 1 second. I also set the Cycles per second to 192...so the Target Helper is going to spin 192 times over 24 frames. In the Render Room I checked Motion Blur only - no Vector Blur - and checked Backward and Forward Blur, and set Blur Intensity to 50. Initially I set the Extra Frames to 60, but it looked awful, lots of banding. I bumped it up to 120, still bad, and settled on 240 Extra Frames. In the timeline I moved the playhead to 1 second and rendered. Attached is the result.
In your image with the "straight line" motion blur, what exactly is rotating? I see hints of motion blur on all parts of the object?
hrpschrd, I should learn to read...I think you want to rotate that pink sphere 90 degrees and have a nice motion blur trail behind it, like the attached image?
Edited to add: Image showing settings and relationship of objects. The Spin Modifier is added to the grey sphere, which has the top cylinder and pink sphere parented to it.
I'm trying to figure out why your blur is like that hrpschrd...
It's important that you have the "hot point" (ie, center of rotation) at the correct position for that object. Otherwise when it rotates it won't rotate the way you want, and won't generate the correct blur. Is the hot point located at the correct point?
Yes the hot point is in the middle of the four black spheres so the rotation is in the y-axis as seen in the Assemble room. I notice that with a frame rate of 24 and spin speeds of 28-34 I get a blur like that shown (actually 31). It is rather sensitive. I assume that is because of the relationship of spin and frame rate. That still should show a blur arc instead of a striaght blur, huh?
By the way, the blur comes from behind only when forward and backward are chosen. With only one of those I get no blur. This is flaky.
DesertDude;
Your pink sphere is better, although since the grey sphere is included, shouldn't it be blurring too? I have the whole molecule rotating but the four black spheres are in the rotation axis and not moving. I want to see the whole middle "triangle" rotating. I will try your settings. This is really trial and error. Seems like there should be more reason.
I did a quick render of a motion blur of a spinning blade-type-thing hovering above a ground plane-type-thing, and did a motion blur thingy, with 100% vector blur and like 90 "extra" frames. Just cuz I like extra frames.
And the internal effect seems to also blur shadows, and the results seem okay.
Of course, the motion blur effect really has very little in the way of flexibility, like allowing you to change shutter speed and stuff, so you have to mess around with the speed to get the look you want. Oh, and don't forget to change the Motion/Rotation Controller to Angles rather than Quaternion.
And here's a faster rotation to simulate a slower camera shutter speed. I think that's the only way to vary the "length" of the blur. Which is why I tend to look elsewhere for blur effects.
hrpschrd, thanks for clarification as to what is rotating...
Thanks JoeMamma2000 for another important point for the OP to get the desired result.
hrpschrd, you may have to 'Group' things and move the Hot Point of the new Group (select Group and hit Caps Lock on your keyboard, then move Hot Point...this applies to any object, not just Groups...). Then apply the Spin Modifier to the Group. Sorry for quick explanantions it is late here and I need to got to sleep...
Edited to add: screen grab of Group with altered Hot Point...everythinh spins around that Hot Point...good night.
DesertDude; yes I have grouped the rotation, although I used the whole molecule which is ok because with the hot point in the same place that you have it, the black spheres rotation is just not seen. I assume that doesn't matter but I will change the grouping to see.
I suspect the issue is with the settings of spin rate (31), frame rate (24), number of seconds (24), and something else maybe. You are getting what I wanted. Can you give me more details from the Assembly and Render screens? Thanks for the late hours!
hrpschrd, okay, first picture shows the whole object, made up of parts. I created that very quickly based on your model - I'm sure yours is constructed differently.
Second picture shows the black spheres hidden - if they aren't rotating, don't group them with the rotating parts. Looking at your image with the "straight line" motion blur, I see slight motion blur on the black spheres, so...I think that rotation is "seen". Also note the Group, called "grey_cylinder_group", is selected, and I have moved the Hot Point to the bottom of the Group.
Third picture is a screen grab with the "grey_cylinder_group" selected, and above you can see the Spin Modifier and settings I used. It also shows the timeline, where I have placed the playhead at the 1 second mark. There are no keyframes. Be sure to choose the correct 'Axis' for your spin! My object is facing down the 'X' axis, so I chose the 'Y' axis in the Spin Modifier. I also had to use a negative value in the 'Cycles per second' to get the blur in the right direction based on your example - yours, again, may be different.
If you look a couple of posts above, you can see a screen grab from the Render Room for the Motion Blur I used. I haven't changed it since.
I see you have written that this is 24 seconds long? Is this an animation, or still picture? If it is a still picture I think 24 seconds is overkill and may be causing part of your problem, but I'm only guessing...
I hope that's helpful.
DesertDude: I went back to your previous posts and saw your settings. By changing to -25 cycles per second and using 60 extra frames I got this.
By the way, perhaps you can explain why the rendering changes direction if you do it with the Sequencer at the end or the beginning?
Is that what you are aiming for? I would increase the extra frames to get rid of the banding. Did you re-arrange your object? It looks like a slight blur is being applied to the black spheres and their connecting cylinders - like a faint grey outline.
Hmmm...very interesting and I have no idea. Maybe a Carrara guru will see this in jump in with an explanation. I looked at the manual, including a section called "Motion Blur at Time 0", but I am clueless for an explanantion.