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The glTF Advantage

By: Ryan Lynch

Starting with version 11.5, STK can incorporate glTF models, drastically enhancing the graphical representation of your scenario. Among many attributes, STK provides the ability to present large scale systems clearly, and aesthetically to a wide range of audiences. By utilizing this new feature, showing off your scenario to peers and colleagues has never been more enjoyable! In this article, I'm going to show you firsthand what a standard model looks like compared against an upgraded glTF model.

The Broad Strokes

glTF (Graphics Library Transmission Format) is an open source, physics-based rendering format that enables you to create a completely customizable 3D model with shading effects. You can specify the reflection properties of a material across all individual components on a given model. The glTF model is then compressed into a binary .glb file which is used as the STK standard. A binary-formatted file combines textures and images into a single file, allowing for more optimized integration within STK. To learn more about creating your own glTF model check out our blog, Software setup for converting models to glTF.

See The Difference

Using the STK snap frame feature, we captured images, shown below, of the same GPS satellite type, but using different model formats.

The image on the left shows the satellite model using the legacy .dae file format.

The captured image on the right is the same satellite model (with the same lighting conditions), but now represented in the .glb file format. The view of this image is adjusted to portray the effects of the Sun’s lighting relative to the model’s defined material reflection attributes. The quality of the .glb model is clearly superior!

Image on left shows a model using .dae file format. Image on right shows the same model using .glb file format.

One Step Further

In addition to defining your model's material characteristics, STK also allows you to customize the environmental lighting conditions. This can be done by selecting the reflection settings to be image-based, rather than your procedural environment , as shown below. Using HDR (High Dynamic Range) image files gives you the ability to model any type of lighting environment you see fit. Free assortments of various HDR files can be found online, or you can take your own and import it directly into STK.

Explore what your ground station would look like during a full moon on the beach, or a pacific bound fighter jet during sunset. Whatever your case may be, STK now gives you the graphical capabilities to accomplish just about anything. Let your imagination run wild!

Posted: 3/11/2019 8:00:00 AM