STK 12.1 Spotlight: glTF Animations

One of the great new features in STK 12.1 is support for animation sequences in glTF models. Animations have been an essential part of 3D models for a long time, and have been a core part of the glTF specification from the start. STK also has a long history of moving parts on 3D models, using a system called articulations.

Articulations have always been a little bit different from animations, however. An articulation is at home within an STK scenario, with its start time, length, and speed all specified in terms of STK scenario time. Each articulation moves a single part, or a small collection of parts in identical ways.

A glTF model animation can be much more complex, since authoring tools enable model designers to construct an elaborate sequence of motions. But these intricate movements are all tied to a movie clip's clock — typically lasting only seconds or minutes — with no concept of STK scenario time, date, or time zones.

STK 12.1 smashes these worlds together. For example, your glTF model could contain a detailed animation featuring dozens of partially-overlapping movements that deploy a spacecraft's solar array. Your mission may call for these movements to begin on a particular date and time, which could be subject to change. In STK 12.1 you place a single articulation to play back this entire animation. The articulation supplies the start time and duration in terms of the STK scenario clock, and the animation takes care of all the moving parts. If the mission is revised to push the deployment to a new time, there's only one articulation to update. If the deployment sequence gets altered, the model designer can use industry-standard animation software to get the best level of control over the moving parts. We think it's the best of both worlds.

Learn more

Watch episode 43 of AGI Geeks to see glTF animation sequences in action.

And if you want to learn how to create models in glTF and work with animations and articulations in STK, check out our video series, "glTF Model Authoring Pipeline," on YouTube. Or, you can jump right in here:


Systems Tool Kit (STK)

Modeling and simulation software for digital mission engineering and systems analysis.