From tabletop chess to 3D scenario
Among the rules of chess, there is a special one about “promotion” of a pawn, where it may transform into a queen once reaching the bottom line on the opponent’s side. In real tabletop scenarios you would have to switch the piece manually.
What if there is a pawn piece that can actually, physically transform into a queen? Think about it, this would probably mean a lot of sub-components moving in different directions like what happens to a transformer.
What if we design a 3D model that visualizes what it look like, using the capabilities 3DEXPERIENCE CATIA?
Visual ScriptingMechanical & Shape EngineerMechanical Motion DesignerProduct Experience
Concept & detailed design
The first step is to model the start and end of the transformation – pieces of a pawn and a queen. Thanks to that chess has been around for a very long time with various variations, we had a lot of easily accessible references on what are the shapes of a pawn and a queen, in the form of pictures or simple schematics.
With CATIA’s new Sketch Tracer app, we were able to easily place reference pictures and schematics in 3D space, adjust their locations, orientations and ratios with ease.
From these pictures we drew sketches and model a pawn and a queen, and started taking a closer look at them to decide which part goes where.
With Generative Shape Design, we could easily model the pawn and the queen’s shape, breaking them apart and move them around to see which part goes where.
Oops – seems that the queen is much larger than a pawn, and in order to make the transformation work as intended, we need to break the model into many different “regions”, each fulfilling a specific motion designated to them.
Specifically, it would be essential to model the “from” and “to” of the queen’s head, which is inevitably rather complex. To show a “slice” of it:
In order to make sure this part works, and more importantly, in order to be able to model with ease and be able to come back and modify afterwards, here we used the new Visual Scripting app to enforce a rather new design methodology driven by logics and parameters:
This logic is capable of doing many things that otherwise could be very difficult.
For example, we could change how many “layers” the piece would have, and although this creates new entities, we would not need to manually reconnect the input and output of downstream commands to say make extractions or calculate displacements for these new entities, for that the logic is already crafted to take this into account, making sure that downstream computation is performed on two “lists” that has aligned numbers of entries.
This might sound a bit more programming than mechanical design, but that’s the beauty of this new app: to give mechanical engineers new tools to automate their work.
To sum up, now we have a good concept of the alpha (the pawn) and the omega (the queen), and we also have an idea of how to go from here to there. Now let’s put that into our 3D model!
Assembly design
The next stage is assembly design. This is where things start becoming a bit more complicated, as we are no longer dealing with one 3D model, but many of them, which eventually fit back together as a whole assembly.
What’s more, the inter-relations between these parts or “engineering connections" need to be carefully crafted to adhere closely to reality.
This is where we start diving into the topic of CATIA Assembly Design and Smart Mechanical Component. We defined a component using Smart Mechanical Component, specifying its geometry, impact and mechanism, and then instantiate it whenever possible. This would place many instances of that same component based on a same reference, and after doing so we were able to minimize rework and error whenever we needed to modify that component. We were also able to place an empty “bone structure” of a component, specifying only its reference coordinate system and come back to finish its detailed design afterwards, whenever convenient for me.
(***click on the next video to see how it works:)
It is also worth mentioning that Smart Component works well with some other advanced CATIA features like mechanical system, so it also offers big help to our following topic: Kinematics.
Kinematics simulation
With CATIA Mechanical Systems Design app, I can import aforementioned engineering connections to formulate a mechanism.
It goes without saying that we can also define new engineering connection ad-hoc to make sure it works out in the end, for which CATIA also offer tools to check out the degree of freedom of the mechanical system:
Now to make the mechanism start moving, we are missing one last component: to inject some excitations to the system, for which we used Mechanical Systems Experience.
This Mechanical System Experience app offers the capability to add all kinds of excitations to the mechanical system, using force, velocity or other parameters that adhere to some certain mathematical formula or “law”.
We need one law for each moving part of this model (which is like 99% of all its components), and as soon as we’re done with that, the model is good to go and show how it transforms into a queen!
In order to make it look a bit more sexy and realistic, we would move on to the next stage which is about visualization of this model.
Visualizing a transformer chess pawn – from CAD to video
Materials and lighting breakdown:
We are using three materials for the project: a wood Substance and a silver as well as a golden metal.
For the lighting, I am using a custom ambience, based on an HDRi, but with a solid gray color assigned to the background. Creation of the ambience object is straightforward. Create a new ambience, which will bring you to the Ambience Studio app. Assign the HDRi in the Light Screen tab, then switch to the Background, select Color instead of Map 360 and choose a dark gray.
Material Mapping
If we were to assign the wood material to each of the elements of the pawn, we would get visible seams between the parts and the direction of our wood texture might not be consistent (see illustration below). Since we want to create the impression of a regular chess pawn, made from one single part, this approach is not sufficient.
Usually, we would assign the material on a higher level, to get a consistent mapping on all sub parts. However, the structure of the pawn does not allow this, since we also need our two types of metals assigned to some components within the structure.
Considering these two requirements, the only solution is to rotate the mapping on each of the segments by 45° and then copy the material to similar segments above it. As a result, we get a material mapping that is consistent across the whole chess piece:
Creating and assigning the metal materials is straightforward and brings us already very close to the result.
Adjusting the playback of kinematics simulation
The data already contained a kinematics simulation and its results. However, to render the video I needed a baked animation. This was easy to do in Mechanical Systems Experience, where I changed the time step value in the Scenario properties to 0.016s, which roughly matches 60 fps. With this improved temporal resolution, I regenerated the simulation result and exported it as an animation.
We now have a Physical Product containing our custom HDRi, the baked animation and all of our materials:
Preparing the scene in Product Perception Experience
Starting from a blank PPX scene, I insert the root product and create a position variant from the kinematics animation. To make things a bit more interesting, I also added a position line to rotate the root of the pawn by 180°. To combine the rotation with the kinematics, I combined both in a new stage variant. A quick test render showed the setup worked in general, but the result was still a bit boring.
I wanted more attention on the final unfolding step of the queen’s head. For that, I went back to Live Rendering and added a spherical area light within the head part. With this approach, the existing animation will take care to move the light along with the headpiece and create a grande finale for our render.
Presented by @KL , CATIA Engineering Industry Process Consultant Specialist and @MR , Senior Portfolio Technical Specialist for CATIA Design and Product Experience.
Inspired by Polyfjord's video. Original:
https://www.youtube.com/watch?v=t-7CFVslli4
Thanks for reading!
