Techniques Used to Create High Resolution Virtual Models of Geologic Specimens Using Photgrammetry

Thursday 1:30pm TSU - Humphries: 203

Author

Ryan Hollister, Turlock Unified School District

Virtual 3D geologic models created using photogrammetry are an extremely useful tool that can increase student access to hand samples and outcrops. A small community of geoscientists, teachers and students have been experimenting with photogrammetry software over the past four years to create a repository of freely-accessible geologic models on Sketchfab.com. In the absence of a geology-specific photogrammetry instruction manual, individuals used varying methods of lighting, photography and processing to generate models that were serviceable representations of the actual rock samples.

Many 3D models made prior to 2017, however, suffer from low resolution and pixel smearing caused by:

  • A lack of photographic overlap between images.
  • Poor lighting conditions.
  • Low resolution images.

When users zoom-in to many earlier models, much of the fine detail disappears. Many of the early hand sample models also exhibit hollow "Hide-A-Key" artifacts on their underside. Such distortions and digital artifacts only allow students to observe general properties of a rock or an outcrop and limit the ability of students to make realistic sub-millimeter observations in the virtual hand samples.

Thanks to continued experimentation and advances in photographic capture and processing techniques, the ability to create high resolution 3D models has dramatically improved over the past three years. This session will present several new techniques used to create extremely high-definition 3D models of rock specimens. Techniques, tips and tricks will include:

  • How to create an inexpensive photo tent and turntable.
  • How to create shadowless, even lighting.
  • How to capture an entire specimen by using pixel targeting.
  • Raw image processing.
  • Improved Agisoft Metashape workflow.

The session will close by presenting several possibilities of how to incorporate HD 3D models into geoscience curriculum at all grade levels.