Using Models

You can use 3D models to represent scenario objects in STK, aiding in their analysis and visualization. The STK installation contains detailed 3D models of many objects, such as satellites, ground stations, aircraft, air strips, naval vessels, and ground vehicles. After identifying or creating a model, you can choose to have STK display your model in the 3D Graphics window using the coordinates and orientation defined in the object's Basic Properties.

Identify or create a model

Choose one of the following ways to select a model for STK to use:

  • Use an Existing Model. You can use one of the models included in the STK installation; go to C://Program Files/AGI/STK12/STKData/VO/Models and select one from one of the topical folders. All of these come in glTF, Collada, and MDL format. These are the only formats supported by STK. Some free online sources and commercial model vendors offer models in COLLADA and glTF format. MDL, however, is a proprietary format that is only compatible with STK and only available through AGI. These models are also available on the STK Data Disc on the AGI website.

    • AGI recommends using glTF models, but supports MDL and COLLADA for backward compatibility with older scenarios.

  • Convert a Model. Many commercial modeling tools, such as Modo, Maya, Blender, and Google SketchUp, can export 3D models to glTF or COLLADA formats. You can convert CAD models through Anark Core, Deep Exploration, PolyTrans, and TransMagic.
  • Create your own Model. You will need a 3D modeling program to create a COLLADA or glTF model (see the programs listed above) or a basic text editor to make your own MDL model (see Create an MDL Model).

Model format types

All compatible models contain basic geometry and texturing. Each model format contains unique capabilities that are described below. You can add functionality and visual enhancements through the use of metadata, which may either be embedded as part of the model file or contained in an external file. This metadata affects how your model behaves or how it looks or both.

  • glTF (GL Transmission Format) is a royalty-free specification for the efficient transmission of 3D content, developed by Khronos Group. In addition to the STK-specific features mentioned above, this format makes use of a Physically Based Rendering shader built into STK. You can use two or more texture layers to show base color, metalness, roughness, ambient occlusion, emission, and normal maps. External to the model, you can also include High Dynamic Range (HDR) reflection maps. The glTF file contains the base model. A GMDF file contains STK-specific metadata (articulations, pointing, etc.). A GLB file is a binary form of glTF which may also contain GMDF data and texture maps used in the model. For additional information, see the glTF models page.

    • AGI recommends using glTF models, but supports MDL and COLLADA for backward compatibility with older scenarios.

  • MDL supports articulated appendages (parts that animate), pointing, attach points for sensors and vapor trails, and solar panel groups. These are STK-specific features and are embedded within the MDL file itself. Unique to MDL is the articulation of colors and textures. For additional information, see MDL Model Parameters.
  • Collada supports articulated appendages, pointing, attach points for sensors and vapor trails, solar panel groups, and the ability to use shaders. Collada also stores normal vectors and uses per-pixel lighting. These capabilities may be embedded in the DAE file or an external ANC Ancillary file. For additional information, see COLLADA Models and Ancillary Features.

For testing and viewing purposes, you can use Model Development Environment (MDE) to visualize COLLADA or MDL models. You can view glTF models using Microsoft Visual Studio Code (https://code.visualstudio.com).

Loading a model into STK

To load your model into STK, right-click the object that you want to apply the model to and select Properties. Under 3D Graphics, go to the Model page. Under the Model subpanel, select the Show check box and identify your model by choosing an option:

  • Select Model File and browse to and select your model using the ellipsis.
  • Select Model List and choose a model from the list.

After loading your model you can:

  • Change its size using the Log Scale slider.
  • Adjust articulations by clicking View under Articulations.
  • Alter the model's orientation or position using the Offsets page of the 3D Graphics properties.