3D Aerospace Design: Creating Real-time Simulations of the Arianespace Missions

Substance Painter

We use Substance Painter for its efficiency and quality in creating high-resolution textures quickly. After some research, to texture our 3D models with as few output maps as possible, we must have two UV sheets per model to keep optimization and gain in resolution. We opted for an ID system by vertex color to be able to assign our textures very easily and quickly, so a little extra preparation on 3ds Max (Vertex Paint) is necessary because baking by material color was not conclusive, as too many small objects make the ID drool.

After the preparation of our models and a well-arranged UV board, we import the model into Substance to bake and recover the various maps – including the ID maps – and then we allocate a texture by color ID, which is very fast after this preparation. Once all the textures have been attributed to each ID, we just export the maps in the desired quality and import them into Unreal Engine 4 or Unity to work on the scene.

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Substance has become the must-have to the 3D manufacturing process in the graphics industry.

When we’ve finished texturing the assets in Substance Painter, we export the texture maps with the preset “Document channels + Normal + AO” allowing us to get 7 separate maps, and so more flexibility – whereas the Unreal Engine 4 preset exports only 3 maps. In Unreal, we put the export maps from Substance into the right slots with modifications by using the “Constante + Multiply” method that lets us recover the rendering quality of Substance Painter, but in Unreal Engine.

Light in Space

Light is very specific in space. Our first step was to find a lot of pictures of real space environments to better understand the different light sources and their behavior. In our case there are two main sources: the direct light from the sun which is very white and very sharp and the indirect light of the Earth which is more diffused, and bluer. These two main sources vary a lot when you turn around the Earth, however, so we had to make a dynamic setup.

The sunlight is fully dynamic and positioned according to real-world timing. When it starts to go down behind the earth and blend with the atmosphere, it lowers its intensity and turns orange until it fully disappears, thanks to the UE4 atmospheric system. The skylight asset updates itself regularly so our ambient lighting always matches the current lighting characteristics. After this point, we should totally be in the dark as we have lost our two main sources. The sun is fully occluded, and we are on the dark side of the earth.

Launcher variations

To date, Arianespace uses 3 kinds of launcher: Ariane 5, Vega and Soyouz. Two new launchers will soon appear: Vega C and Ariane 6.

For each mission, the goal is to put satellites on the right orbit, with the right velocity and orientation so that they can reach their final orbits.

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Satellites are different for every mission, so we produce 3D models for each mission and create the right launcher configuration: the launcher itself, satellites in the right position and with the right clocking (orientation), and dedicated satellite deployers, dispensers and adapters (these are the parts where satellites are attached on the launcher before separation).

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Satellites mainly come from private telecoms. Sometimes, there are scientific missions where satellites come from public space agencies: the next example for this is the James-Webb telescope, which is planned to launch on October 31, 2021

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Recreating the Earth

The Earth is created from public NASA images, cleaned, and processed by our tools. There are a lot of layers to produce such renders at this level of detail:

• Ground textures
• Ice on sea textures
• Cloud textures
• Cloud shadows
• Ground elevation textures
• City lights at night textures
• Procedural noise to add details
• Procedural atmospheric scattering layer

Each texture has a resolution of 131072 x 65536 pixels! We used, of course, optimization strategies to use these kinds of textures for real-time rendering.

Earth is still in progress because we plan to add more details and volumetric clouds in the next versions. We currently do not simulate weather. Clouds are static but their shape is realistic because they come from satellite pictures of actual clouds around the Earth.

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