Caterpillar Animation Test

I recently started a new project. The full project will be a video to show a composting plant and explain how it works.
I started to fiddle with one of the most complex elements in the animation, a wheel loader which dig and carry around different flavours of garbage.

I started to model it in SketchUp to get the most accurate possible geometry for the mechanic animation.
For the front part, I mostly used simple native tools alongside FredoCorner to round off some edge here and there.
The back part was modeled by subdivisions and then converted to plain mesh and optimized to low poly.
I organized the hierarchy and the pivots in a meaningful way and exported the model to 3dsMax to animate it…

In 3dsMax I created a rigged setup… the main rig for the bucket is based on 2 different inverse kinematics chains, one for the main arm and the other for the bucket leverage.
The pistons are simply hold togheter using some “look at” constraint, so that no matter how you move and stretch them, they constantly align themselves with each other.

The whole thing is animated along a spline, which is also animated itself with a series of dummies driving the control points, allowing for multiple paths using a single spline.
Actually there is an hidden mesh which animates along the spline, with a few dummies attached and linked togheter using some more “look at” constraints to properly orient themselves when the vehicle turns left and right.
The actual vehicle parts are linked to those dummies, this was needed because the front part of this beast rotates as a whole and the overall rig behavior is more similar to a train than a “normal car” (I know this may sound a bit confusing, but… it is what it is).

The wheels and the transmission axle simply have their X rotation parameter wired to the main rig X translation parameter along the spline, so that whenever the veichle moves, everything spins nicely accordingly…

After that all this quite complex rig is set up, the whole thing can be animated keyframing only 3 main parameters: percentage along path, bucket height and bucket tilt (and of course the translation of a couple of spline control points when I need to change the path). Everything else follows accordingly.

In 3dsMax I also quickly blocked out a simple test enviroment using freeform and scatter tools to set up the trash heaps.
For the actual plant model I’ll use Sketchup based on cad files coming from the real world project, but for the sake of this test, some quick and dirty playground was good enough to start with… just to check out the main workflow.
In Max I also created a few colliders for the bucket and the front parts to try some physic simulation of the “dynamic” trash…

I then exported the model to Substance for texturing using a couple of UDIM tiles for the main vehicle and a simple atlas for the wheels and tires. Applyed some decals for the logos and used a few generators and particle brushes to add dirt and damages to the materials.

I then imported everything in Unity3d to render it out using the HD Render Pipeline.
I exported different models in a modular way (3 individual fbx for playground/static trash, dynamic trash and wheel loader) for better control and then assembled everything up again in Unity.
The whole lighting is based on an HDRI skybox (with a layer of volumetric clouds added) and a simple directional light for the sun.
In Unity I also added a lot of decals to improve the appearence of the static scene and animated the lights of the Caterpillar just for the sake of fun.
I also created a dozen of smart Cinemachine cameras with different “follow” and “look at” constraints and a bunch of postprocessing effects such as lens flare, bloom, vignette, chromatic aberration and so on…

I recorded the whole sequence and sent it to Davinci Resolve for final postproduction.
I added some cuts to finetune the overall flow and cleanup some imperfection, added the music and the end titles, a couple of simple transitions, but most of all, I used some Fusion effects to enance motion blur and did a bit of color correction/color grading to balance the overall lighting and add a little more of “early morning mood” to the scene.

Here’s the finished test sequence… I hope you enjoy it.


Posted a reply and question on the SketchUcation forum. Basically, excellent work sir.

Fantastic job! Nice to read about your entire workflow. You used (and are familiar with) a lot of tools, wow. :slight_smile:


Crazy good. I hope you got paid good money for it!
Not asking how much but I hope it covered your time.

One very small observation- I see that you’ve done some amazing things with different tools.

Just when the bucket is moving up and down and the digger is lifting- I’d love to see a slight shudder in the body of the digger and slight compression of the front tyres due to the weight differential. It’s a very small thing but would add that extra “zing”

Excellent work though. Keep it up.

It’s great that you wrote up your process for others to get an idea. Thanks for sharing it.


Yes of course this is paid work, of course this is only a test, but the final video will be more than reasonably paid.
I did a separate test for this because it will be the more complex object in the whole animation and it has to work for 5 or 6 different sequences, so I feel that finetuning and optimizing it is time well spent for the overall management of the project.
I actually spent 14 working day on this for the whole process… so I believe that’s not bad and I myself tought that all in all this would have required more time and effort.

Yes, it’s basically true.
I believe the tyres should not deform in any noticeable way because this kind of wheel loaders usually tend to run crazy high tyre pressure and are meant to work with all sort of dirt, stones and concrete, which are significantly heavier than generic garbage, so I believe that’s not a big deal.
But you are definetly right about the supensions and I already noticed it myself when the whole sequence came togheter. Unfortunately the suspension work should be at the very root of the rig.
Appending more stuff to the end of the rig is absolutely fine, but on the contrary, It’s generally not a good idea to mess with the root of the hierarchy when all the good stuff is already done. You do that at your own risk only if it’s really needed/crucial.
By the way, you have to consider that the actual animation will be mostly from a relatively long distance (more in the line of the bird view in this test or maybe slightly closer) so I hope that detail will not be too noticeable… we’ll see… if it will turn into someting important and I’ll have time to spare before the deadline, maybe I’ll try an alternate version with something that can mimic suspension dynamics.
Thank you for your feedback, really appreciated it.


I replied there :wink:

Well I double checked this, and looks like we both were wrong.
This baby is not supposed to compress in any noticeable way.
Turned out that the front wheels are fixed with the front frame to avoid the compression bobbing under heavy load, and the rear part is only oscillating sideway to keep the wheels in contact with the ground (if the ground is uneven, which luckily enough, is not my case).

Here’s a video showing the suspension mechanism closely

Here’s another one showing the baby under heavy load on a more even (but not completely even) ground

Pay attention to how little the tyre deforms under significant load and slope…
In my case I suppose it should be near to zero on flat smooth concrete industrial floor (under quite lightweight load).

And finally look at this… see how the front axle stay fixed when it floats above the gap… nothing to do with a regular car suspension.
Also notice how the tyre is nearly undeformed under such extreme conditions. :open_mouth:

I’m probably safe, LOL :face_with_peeking_eye:

Impressive work :+1:

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Fabulous work - VERY well done :+1:

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I get you that it’s not a normal suspension, but on the first video you can see how the digger “rocks” as it lifts the load. Now I understand it may be unworkable to fit that into your rig. I’m not an animator but I can appreciate it that you have complex heirarchies in what you’re doing.

It’s a case of “nice to have” rather than “need to have”.

Still- Excellent work. :+1:

Of course, but that’s loose terrain as different as it can be from a smooth industrial floor.
I need to convince myself of this, I don’t want to do the full rig from scratch again. :rofl:

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No don’t do the rig again! You’ve done enough already with this. By the way, I really like the random way the dirt falls off the bucket. That’s really cool.


Thanks :grinning:
That’s not exactly “random”, is simulated with collisions and physics.
The static trash is just a random scatter.

Wow. That’s some amazing stuff.

Awesome, making that animation on sketchup would’ve taken a lot of time with fredo animator, rigging is a faster way to animate objects, I wonder if there’s a plugin for rigging on sketchup.

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Yes of course, in particoular rigging with inverse kinematics is way more convenient than with forward kinematics.

To animate something like this using FK, you should animate every single piece starting from the root of the hierarcky and try to predict how it will affect the final position and rotation of the bucket.
Using IK and constraints, you simply drag the bucket at the target position and rotation and everything else along the chain follows accordingly, driven by the constraints you set.

Maybe setting up an IK is a bit more complex than a FK, but once you properly setup everything, there’s a HUGE advantage when it comes to actual keyframing and animation.
Much less elements to keyframe and way less prediction and calculation to do.

Another big problem with animation done straight in Sketchup, is that you cannot export that to other applications such as external renderers or game engines.
Same goes for let’s say Ms Physics/Sketchy Physics, you can probably try to simulate something similar using those (not sure about the processing efficiency), but then you are restricted to use the animation in Sketchup, because currently there’s no way to export that.

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Wow, I don’t visit the forum as much as I should, but that’s incredible work. :clap:

With a gun to my head demanding suggestions, my only one would be a toot of smoke coming from the exhausts after the lights turn on, but that’s really grabbing at straws.

Amazing work and those 14 days were a great investment for that output. :+1:


Fabulous workflow mastery here Marcello! Modeling is only a small part of the job when doing animations… You need to know so many other softs… Unity’s render quality is very good, and having a good knowledge of Resolve is very useful as this video package is fantastic (and free in 1080p)!
I also tried to make an animated scene with SU Max and Lumion but it’s sooo time consuming when you do that only occasionally… Louise Tower, Brussels CIT BLATON on Vimeo :wink:


I tought about that, which would have been relatively easy to do with a simple particle system, but visible smoke from a diesel engine is generally due to poor manteinance and makes for undue pollution.
Now, you have to take into account that this model is not for a videogame or something, but the final animation will be for showing and promoting a composting plant.
The general “storytelling” of the video will be that the pollution footprint of the plant is as low as possible.
So I thought that a diesel engine spitting out more pollution than it should, would not have been a great idea. :sweat_smile:

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Yes I feel that Unity is way underrated as a “render engine”. It can do a lot more than just videogames and VR.
I myself prefer Unreal for more “static” archviz walktrought and that kind of stuff, but when it comes to more complex and “functional” animation I tend to prefer Unity, i find it more flexible and straightforward with complex timelines. And the quality is pretty decent if you use the High definition Render Pipeline (still UE5 is a bit better in terms of graphics).

And yes, Davinci is outstanding and is free also for 4k output, not only 1080.
Studio version can output up to 8k I believe, but the main differences are more in terms of added FX, gpu rendering for the final output and more customizable interface (I believe I’ll buy the studio version, now that I’m using it more and more).

That crane sequence is really impressive, I would probably have kept the animation just a little slower so that one can appreciate evev more the fine movements of pistons and stuff…
You did the rig and the animation in Max and then render it in Lumion? I didn’t know that Lumion could manage such complex custom animations… :open_mouth:

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