Hello! This week we're getting started on the shot recreation. My goals for this week are to get proxies modeled for the helicopter, missile and warship (the one in the background shooting the missile), and then getting into Houdini to start laying out and animating the scene. I'll also get started on some R&D for pyro fx.
Starting to Model
All 3D modeling will be done in Autodesk Maya. Let's jump right in!
The first step I take for any 3D modeling project is creating a proxy. This just establishes the basic forms and proportions of the model, kind of like a 2D sketch.
The Missile
I'm going to start with the missile, as it's a basically a cylinder with some trapezoidal "wings" sticking out. Even though it's not going to be too visible in the final shot, I found some other clips from the film that give a closer view of the missiles that I can use as reference:
The clips also give a good idea for the size of the missile, so I can scale up the model accordingly. Here's the final model:
The Dragon
Now that that's finished, I'll proxy out the Dragon warship that shoots the missile. I'm not too worried about getting this one perfect, since it's a background element that I have no plans to fully model.
Now the Dragon has a very...peculiar shape. It was also surprisingly difficult to find good reference of its side profile, so I'm doing what I can using the reference I already have. I'm going to time skip ahead to when the proxy has been completed. Here it is:
Admittedly...it's not my favorite. But this was made very quickly as it is supposed to be just a very rough blockout, and the silhouette works from the angle it is scene in my reference shot. So I'm going to call it here. A quick google search revealed the dimensions of the ship so I scaled it accordingly.
The Samson
Now for the main event, the Samson helicopter! I'm going to be spending quite a bit more time on this proxy since this is the asset that I'll be making a high-res model for. I was able to find a lot more reference material for this craft, which I've put together in an app called PureRef. This app lets me layout all my reference images in a single document with infinite zoom, so I don't have to worry about constantly switching tabs to a new reference.
I also upload some reference pieces (particularly orthographic views) on to planes in Maya so I can easily compare proportions (I did the same for the Dragon proxy too, they're just hidden in the above screenshot).
One last thing before we get to modeling the proxy: I found this very interesting article by Andrew Chan on how the Samson prop was created for the movie. It breaks down a lot of the components which gives me a really great reference to work with when I get to the high-res model. Go check it out, it's a very intriguing read!
Now the most major pieces of this aircraft are the cockpit, midsection, rotors, and tail. So, those are the pieces to proxy first. At this point, it looks a little wonky, but keep in mind that I'll be continually touching up this proxy throughout the week. My goal is to have it completed by Sunday.
As I'm working on the model I'm also making sure to freeze transforms and delete history regularly, and making sure to always rename my objects as I go. It's better to keep up with renaming right at the start, rather than waiting until you're finished and have too many pieces to keep track of.
Ok. I've added some larger pieces to the proxy now such as the bars that connect the rotors and the landing skids. Looking slightly less wonky now:
I'm going to call it a day now on the proxy model. I want to jump into Houdini as soon as possible to start laying out the scene and I can always hop back to the proxy afterwards and keep importing the updated versions into the Houdini project.
Oh! One more thing -- I'm going to duplicate a copy of the main body piece for later and then hollow out the piece I have. This is because the initial fire from the start (which is the first fx element I plan to work on after setup) starts on the inner ceiling of the helicopter then crawls outside. So, I need a hollow model. I went ahead and deleted some faces for the windows too.
Note that the interior cutouts aren't too proportionally accurate right now. I don't typically proxy out interiors unless the camera actually goes inside the model. Right now this is done so that the fx element interactions with the model still maintain accuracy (like some of the flames bursting out from inside of the craft and out the windows).
Alright! Now we're ready to go to Houdini
Setting Up the Houdini Scene
Environment Blocks
...but first, just a bit more to do in Maya (Sorry!)
You see, the environment for this shot is very complicated, with all the floating islands. It likely wouldn't work if I just used a flat backplate. So, I'm going to roughly block out some of the islands in the mid-ground to lay out in Houdini so I get a better sense of the scale and positions of everything in the scene. Getting this done will also help me nail down the animation and camera movement by giving me many points of reference to work with.
In the future, I think I might ask my friend and fellow artist Vy for some advice on creating procedural rocks in Houdini to replace the block-outs. She created some very awesome procedural environment pieces for a Black Adam shot recreation we collaborated on. Check out her website here!
So, I went ahead and created some very basic shapes in Maya to act as the floating islands. I pinpointed the islands closest to the camera as well as the giant rock columns that show up at the end of the shot at screen right to start with, before moving on to create a few more general shapes. The scale is a little more difficult to gauge at this point, so I'll work on resizing them more accurately in Houdini.
Asset Layout
Alright! We're finally in Houdini. I created a new project and scene, and now it's time to import all the assets. I'm splitting these into two groups: ASSETS and ENV_ASSETS.
I first started by importing all my assets into the scene, and then I began to lay out the rocks as closely to the reference as possible. After multiple tries at this and testing different camera angles from the shot, I realized that it's actually rather difficult to gauge the scale of these islands. They're absolutely massive and all different sizes and distances from the camera and at some point it just got too frustrating to try and lay everything out.
After a while of contemplating and thinking over alternate routes, I decided to first build the first frame of the shot then move on from there. I also remembered that the islands weren't my only point of reference: I had the Dragon warship too. And since I know the exact dimensions of the Dragon and already had it scaled accordingly in my scene, I could use it to much more easily lay out the first frame of my shot using only it and the Samson. Then, I brought in the main island that sits behind the Samson and positioned it as well. I had to scale it up quite a bit so I could keep it at a far distance while also still having it fill the frame. Then I finally laid out a couple other islands that served as main reference points in the shot.
Now I could begin animating.
Animation
I'm going to start this section off with a little lesson I learned in previous Houdini projects. When I used to animate objects in Houdini, I would dive into the geometry node to create a transform node, and then animate off of that. It was much later when I realized that in many cases it's probably more efficient to animate from the upper most level of the geometry node itself. One reason for this is when you are parenting nodes, the child looks at the transforms of the geometry node itself, it doesn't parent to the transform node inside. Secondly, it makes it easier if you want to separately animate smaller components inside the main model, but still need a master transform. I'm pretty sad and a tad embarrassed that this never crossed my mind so much earlier, but hey always good to learn from my mistakes.
Ok, so. Animating the shot:
After I prepared the first frame, I went on trying to match the camera angles second by second (I tend to create my keyframes every second/ 24 frames) and then moving the Samson into position as well, adjusting the animation through the graph editor as I went. (The Dragon also moves too, but very little)
...this process worked for about 50 frames before I ran into issues. The animation of the shot began to look disjointed after the 50th frame as the camera and helicopter animations didn't line up properly. While things looked fine on each individual keyframe, the in-betweens revealed odd, jittery motions. I tried adding more keyframes between frames 50 and 72 so I could try to iron out the issue, but it seemed to be getting worse.
It is at this point I remembered how not-much-of-a-fan I am of animation. I was also running out of time in the week, so I decided it may be best to call it here. I had the first 51 (or so) frames looking decent, and that's all that was needed to create the initial column of smoke and a missile trail. And since I was getting quite anxious to start actual VFX work, I decided I'd do just that and leave the remaining animation work for the weekend.
...On second thought...
The night is still young!
Well about 15 minutes after I wrote that paragraph of only getting 51 frames I decided nope! I'm finishing this. I added another island for a point of reference then deleted everything after frame 51 to redo things from there. It took quite a bit of time and scrubbing between the reference shot and my own...plus struggling with gimbal lock but I got it! Mostly at least. Admittedly it's still a little bit janky but I'll work on correcting that over the weekend. At least I have all 6 seconds drafted out than only 2 :)
How I Animated the Missile
One thing I forgot to animate was the missile. This one isn't too difficult though, I only had to really focus on getting the first 18 or so frames right, after that it more or less goes in a straight line towards the Samson. I only animated the translation though. For the rotation, rather than keyframing it, I decided it'd be much easier and more efficient to use the velocity and normals as my guide. What I did was animate the transforms using only a sphere. Then, I extracted its centroid and got its point velocity using the point velocity node. Using an attribute wrangle, I set its normal to equal -1 * velocity. After that, I could simply do a copy to points with the missile to the centroid, and with "Target Point Orientations" checked on, the rotation of the missile was now animated! I also keyed the missile to disappear by scaling down to zero when it impacts.
Here is the final animation for this week:
Now that the thought of unfinished animation can no longer haunt me, we're (finally) moving on to VFX!
Also, here's a friendly note to always save your scene!
Fire VFX R&D
It's morning and it's research time! Professor Lim sent me a couple very helpful videos about creating fire in Houdini, so that will be the first order of business.
Time skip! I went ahead and watched the videos my professor sent me. Using the info from that, as well as from Houdini documentation and my old VFX course material, I felt ready to tackle the initial fire and smoke.
I decided to start with the smoke, since I already have some familiarity with it from my Interstellar shot I did a few months back. I started by isolating the section of the Samson that is supposed to be on fire, then used a Pyro Source to scatter points and create temperature and density values. Then, I added noise to both before volume rasterizing the attributes and diving into the pyro solver. This is where most of the work is done. Initially, I had the velocity attribute turned on as well and using the Samson's point velocity, however I quickly realized that that wouldn't be needed, as it would just throw the smoke around wildly. In the reference, the smoke just seems to float gently upwards, so buoyancy was really all I needed. After that, I went into the shape tab to add some noise to my smoke, as initially it just looked like a uniform grey mass. I ended up having to turn the turbulence way up before I finally got closer to the look I wanted.
Now that I was happy with the shaping, I decided to turn the dissipation value to zero. This is because the smoke in the reference never seems to fade. I keyframed it to turn all the way up to 1 between frames 48 and 60 though, since it is no longer visible after the missile explosion. After all, I didn't want to force my pc into doing more work than it needed. Following that thought, I also limited the max bounding box size so the smoke wouldn't rise too high off camera (after all, it wasn't dissipating for the first two seconds.
Here is what the smoke looks like:
Now for the fire, I followed a similar process, except I primarily used the attributes of temperature and fuel. I added only a little bit of noise to the fuel attribute, as there isn't much breakage in the brightness of the fire that can be seen in the reference. I also upped the element size on the noise for temperature. Finally, I had to turn down the fire lifespan down to something like 0.2, since it doesn't rise very far (it still looks too high in some parts though, and feels too low in others. I'll need to mess around with it).
Here is the fire:
Once I had both of these elements finished, I added post process nodes to both, a pyro bake volume node to the smoke to adjust the color, a pyro bake volume to the fire to adjust its intensity, and then file cached both.
Here are both elements together:
Getting Started on a Missile Trail
I got a little bit of work done on the missile trail as well, though I didn't get too far.
My professor suggested I try volume instancing with particles, so I started by creating a particle system.
First, I selected the faces at the very end of the missile to act as the emitter. I scattered some points then grabbed their velocity with the point velocity node. Then, I created a POP network. The initial results were...not good. I had to use an attribute VOP to turn the velocity way down so that the particles wouldn't just fly off the screen so quickly. That was an improvement, but I was still getting this stepping effect due to the speed of the missile.
Not knowing what to do, I decided to add a POP force node to see if that could break things up a bit. I added a bit of force in all directions then bumped the swirl size and amplitude values way up. This helped only a bit, mostly at the beginning of the missile's flight path. However, stepping was still visible near the end.
It was after scratching my head for a bit and just messing around with values that I found the magic button: Jitter birth time. Now that doesn't do much by itself, but after setting "Interpolate Source" to back and "Interpolate Method" to match topology, all the problems were solved. I turned down the POP force amplitude quite a bit because things just looked too noisy now, but here is the final particle trail!
Now, for volume instancing, it's not something I am very familiar with, and I couldn't find much online about it. So, I decided to try out sourcing pyro smoke from my particles. I had previously done a similar experiment with POP systems and pyro over winter break, so I figured it was worth a shot.
...It didn't turn out too well. The smoke looked clumpy at best even when I turned up the noise and lowered the voxel size to better match the size of the missile. However, I just couldn't get away from the clumpy look, and at some point my pc decided it had enough and began whirring at me before starting to freeze up. So, what I was doing was probably not the way to go and I scrapped that plan. Running out of time now though, so I'm going to just stop at where the particle system is then ask my peers and professor for more advice when it's time for our weekly check in.
For now, I think it's about time we got to rendering!
Preparing the Scene for Render
Moving on to Solaris now!
The first thing I did was import my assets into Solaris. I then created materials for them using Karma's materialX shaders. The Samson and Dragon just got a metallic material matching their colors, and the missile a slightly rougher metallic white. For the rocks, a simple matte beige would do for now. In terms of lighting, I matched the colors and directions as best I could with the current blockiness of my assets, but proper lighting wont get done until said assets are more developed.
Next, I had to import my fx elements, which was just the smoke and fire. I also created materials from the pyro bake to assign to my elements. Unfortunately. It seems that the fire element is refusing to show up in render view. When I view the SOP import I just get a grey blob, and then when I jump to the assign material node it disappears all together. It makes the smoke disappear too when I merge them into the main line.
Unfortunately, I haven't been able to figure out a fix for this as of writing this. I think I'll have to ask my professor during our weekly.
In the meantime, I went ahead setting up my render passes. Right now, I only have one for the environment, one for the assets, and one for the smoke. I'll split the assets up more once I have more fx elements to work with between them, but for now I'll keep it as is. I made sure to matte out the Samson in the smoke pass.
Alrighty. Now all that's left is to render!
Compositing
Now that my renders are complete, I just have to composite them in Nuke. Early on, our professor doesn't allow us to do much grading work in Nuke, just so we have more practice in getting the elements to look as close to the end product in Houdini as possible.
Here is the final render:
Here is a flipbook with the missing fire (still haven't figured out why Solaris won't render it) as well as my in-progress missile trail:
See you next week!
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