, by Sebastian Marek

3DIY: Kitbashing a Mechanical Spider

Sebastian Marek details how the Substance 3D Assets library helps him focus on creativity and motion design.

  • Design
  • Interview

I’m Sebastian Marek, and I’m a freelance 3D artist based in Warsaw. Over the past few years I’ve gained experience in a range of companies, working on different types of projects, such as user interfaces, virtual reality, still images, and animation. This diverse path has helped ensure that I’m comfortable working in a range of styles, categories, and visual languages. 

The Adobe Substance 3D team initially approached me with a very open brief: take objects from the Substance 3D Assets library and essentially just play with them – that is, simply create a fun project, in whatever creative direction I wanted. I came up with the idea of creating a short animated sequence built around the Do It Yourself method, which involves using existing raw materials and parts to produce something new. Overall, I wanted to demonstrate how to take individual elements from the asset library and combine them into something new. The action begins with a shot of a desk from above, where seemingly random hard-surface elements appear. Initially all separate, they soon begin connecting with one another.

As objects break away from the desk surface, the action moves smoothly to close-up shots. In this section, we see how the individual elements begin to connect into bigger pieces. These shots are intended to show off nicely executed models with a high focus on the materials and textures.

Finally, the camera leads from macro shots to a full product reveal, ending with a wide shot of the components combined into a machine spider toy landing on a desk.

For more information on how Sebastian works with Substance 3D Assets, take a look at his previous article: User’s Journey: The Creation of a Cinematic Loop Animation. 

The Machine Spider Toy

The Substance 3D Assets library has a lot of hard-surface resources with parts such as hinges, housings, connectors, etc., and I decided they seemed perfect for building a machine spider toy using the kitbashing technique. Essentially, kitbashing is a process of taking multiple parts of 3D models from a set of consistent objects and combining them to create a completely unique new object. In the case of a project like this, this approach is very efficient, as we bypass the 2D concept phase and then the time-consuming modeling process so that we can concentrate more on creative tasks such as look development, rather than trying to figure out the right topology of the model. Furthermore, the whole concept is carried out using 3D tools, so fitting objects together and deciding how they will move can be done simultaneously, without having to go back to the 2D concept if something doesn’t work in the rigging or animation stage.

I started with a Cross Connector Plate as the base for the 4-axis machine toy, and then around this object I began to connect various parts until I got a well-balanced spider leg. Once that was done, I only had to copy it three times every 90 degrees to complete the base. 

Kitbashing can sometimes be tricky because the individual parts usually don’t fit together perfectly. This is absolutely fine – the idea is to create an overall impression of the model as a whole because, in the end, usually the artist who creates it is the only one who can see any overlaps or errors.

Next, I wanted to make the spider more believable as a toy by adding subtle details resulting from the manufacturing process to several parts. For instance, toy parts usually have a characteristic line in the middle that results from the process of injecting plastic into molds that are not perfectly aligned. 

All the assets from the Substance 3D Assets library have correct UVs, so I decided to paint this detail on the height texture in Substance 3D Painter. To do this, I created a base material with a gradient as a mask in the middle with a warp filter to add some variation to a straight line.

After Before

Another characteristic of toys: some of the larger plastic parts are usually split into pieces. I thought this might be another nice detail that highlights the feeling of the toy. This time I took a different approach and modified the object at the geometry level. All the pieces have the correct topology ready for subdivision, so all I had to do was select the center edges, then chamfer them and extrude them to the inside to get the desired effect.

After Before

I also added some symbols as displacements, the type of thing that might often appear on toys.

After this, it was time for shading development. I wanted to have the same texture scale on every element, so I created a base plastic with textures applied using triplanar instead of using UVs. I started with basic properties of the plastic, such as base color and reflective roughness, which was broken up with the roughness texture from the Troweled Concrete material. I then reused that same texture for the bump map to break up the perfect plastic surface a bit. I find that the addition of subsurface scattering (SSS) makes a huge difference when it comes to plastic shader realism. With SSS, the material appears to be a translucent object, penetrated to some degree by light – just as in real life. Lastly, I added a slightly lighter base color on the edges controlled with curvature to further enhance the impression of light penetrating the surface.

In the last shot, I wanted to end with an effective landing of the spider on the desk. To accomplish this, I needed to rig my model. Again, I took advantage of the fact that the leg on each axis was the same, so I had to build a rig for just one leg and then apply it to the rest. This saved me a lot of time, but it wasn’t ideal because this meant I couldn’t move the spider’s legs separately. Even so, this was enough for the purposes of this shot. I started by creating a hierarchy of groups for the leg and, based on that, I made a rig using the IK (inverse kinematic) method; this essentially means that, when I moved the spider’s body up and down, the legs would follow automatically (and this, incidentally, is the opposite of the FK, or forward kinematic, method, which would have required me to animate the parts of the leg one by one to get the animation). 

With my rig set up, the last thing to figure out was the piston with the spring at the bottom of the leg. I ultimately used a constraint approach to build a relationship between the spider’s body position and the piston angle. So, when the spider rises and straightens its legs, the piston rotates according to the position.

Additionally, I shared the spider in augmented reality with Adobe Aero. This required me to optimize my shaders, due to the fact that in augmented reality the image is generated in real time. After this, the rest of the process was really simple. I just had to bake the animation and export as an FBX file, and set the trigger so that the spider jumps when tapping the screen. Below is the generated QR code for you to download into Adobe Aero to test out the spider and interact with it on your desk.

Assembling the Scene

The entire animation takes place in a teenager’s room, where all the tools for creation can be found. While working on this scene, I wanted to capture the idea of finding the right balance in 3D between an artistic and a technical approach, so I decided to build the final scene to represent that. Therefore, on the left side, I placed objects that might be associated with art, such as art tools and an abstract painting on the wall. And on the right side I’ve placed objects that are more technical, such as books, notes, and blueprints. The spider machine toy which lands in the middle is the result of combining these two worlds – artistic and technical.

In addition to using materials from the Substance 3D Asset library, I also created my own textures in Adobe Illustrator, such as a technical drawing of a spider model, and a cutting mat texture.

My main light source for this scene was the physical sky and sun with portal lights placed in windows to cast more light into the room and support global illumination. After getting the right direction and intensiveness, I also added area lights placed at the top to fill in the shadows a bit more, and at the bottom to fake light reflections from the sunlight hitting the floor. At this stage, resources from the library, such as windows and plants, really come in handy to block sunlight and create nice shadows on the wall.

Animation and Editing

Most of the shots were animated using the pose morph approach. That is, first I determined the starting pose, and then the ending pose with different position, rotation, and so on. Once these two poses were set, I created the animation by blending between these poses with a simple slider. The key value for me in this method is that I don’t need to animate the rotation and position on every axis separately. I only have to work out the right timing between these poses on a single curve. This makes animating and iterating quite fast, and when I’m animating things being assembled it works exceptionally well.

Due to the small scale of the project, I decided to edit and color correct only in After Effects. At first, I prepared a previz using viewport renders to set a general rhythm and give the Substance team an idea of the entire animation sequence. Once we’d agreed on this sequence I started polishing the animation and working on the lookdev simultaneously to deliver final renders. Before I released the final files, I adjusted the color, contrast, and light on each shot separately using Lumetri Color Effect. The changes were subtle because all the shots are from the same lighting and environment.

The final animation was 12s long (30fps) and was rendered using Redshift on a single RTX3080 Ti GPU at 1920×1080 resolution. I later took the rendered video to Topaz Video Enhance AI to upscale it to 4K, while adding sharp and natural video detail. This is how my process usually looks for final outputs at higher resolutions than FullHD, and it helps me save a lot of rendering time.

Takeaways

I use Substance tools on a daily basis for personal and commercial projects, but this was the first time I’d used Substance models. As I mentioned, I’ve often had problems with kitbashing, because the individual parts usually didn’t fit perfectly, had the wrong topology, and didn’t have UVs, as they often came from CAD software. However, the quality and variety of the Substance models impressed me. They all had the correct topology, so I could modify them easily, and the large library of assets and categories made the assembly process pure fun. I therefore was able to focus more on motion design than asset creation.

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