3-D Models Provide Virtual Objects That Enhance eLearning

Imagine providing 3-D (three-dimensional) models forlearners to study—medical models, 3-D reproductions of sculptures, geographiclocations, even of people. Now imagine creating these models easily andinexpensively. Using a 3-D model moves learners toward fully immersive oraugmented reality experiences and adds exponentially to the potential forinteractive learning.

Creating a 3-D model using photogrammetry is ashoestring method of creating a virtual object for study. Learners can view andinteract with a 3-D model using their computers or mobile devices, turning themodel around and looking at it from various angles. Online clothing retailers,for example, sometimes use this technology to show the fit of the clothing fromall angles on a 3-D model that stands in for the customer.

Photogrammetry and smartphones

A 3-D model is produced from digital still photographs, notfrom video. An eLearning developer can create some 3-D models—of a person,a sculpture, or a building, for example—using a smartphone camera and free orinexpensive software, such as the 123D Catch app. Creating 3-D models of larger objects or locations or generatinga digital elevation model of a tract of land requires aerial photography.

The process of photogrammetry converts multiple overlappingphoto images into a 3-D model of an area or an object. It’s also used to createmaps and measurements.

• Aerial photogrammetry uses aerialphotographs, taken from a drone or airplane, to create maps or digitalelevation models. The camera shoots multiple overlapping images of the groundalong the flight path.
• Close-range photogrammetry uses photostaken with a handheld or tripod-mounted camera; the results are converted to 3-Dmodels using point clouds. A 3-D model of a building or an object of any size canbe created this way; some models can be printed using a 3-D printer.

Though the technology is easily available and affordable,getting good results requires some preparation. Sketchfab,a website devoted to 3-D content, offers a wealth of advice and examples,including these basic tips:

• Any camera that takes high-resolution images cantake suitable images for photogrammetry; fixed-length lenses will producebetter results than wide-angle or other distorting lenses. All photos should betaken using the same focal length—no zooming.
• A tripod is invaluable to minimize movement andenable longer exposure times; any movement of the camera or subject can causeblurred, and therefore unusable, images.
• The photogrammetry software will produce thebest results with textured items, such as rocks or tree trunks; shiny or veryflat objects will not work as well.
• Good lighting is important, though it does nothave to be bright. Even lighting will produce better images than subjects shotin shadows or changing light. If shooting outdoors, an overcast day is betterthan a sunny day with reflections and shadows.

Successive photos should overlap considerably. This enablesthe photogrammetry software to identify the same point in different photos andcreate an accurate 3-D model. To ensure accuracy, Sketchfab suggests roughly 60percent overlap between photos. The number of photos needed will vary, but it’shard to overdo it. Blurry photos must be discarded, and any extraneous photoscan also be discarded; having too few images will harm the quality and accuracyof the model.

Photogrammetry software uses a series of triangulationalgorithms to calculate the angles and distances between points in the images.It creates a “point cloud,” a series of dots that, eventually, forms a 3-Dimage of the object in the photos. If a section is missing or shadowed toodarkly, it will not show up in the point cloud, and there will be a gap in themodel.

Using photogrammetry projects in eLearning

Instructional designers can use 3-D models created using thephotogrammetry process to enhance or create virtual environments for VRprojects, such as simulations or games, or in eLearning that emphasizes studyof an object or place. 

The models offer realistic imagery for learners who arestudying anything from anatomy to geography. While learners might not be ableto see a work of art or an archaeological site in person or get to ageographical location, they can explore or examine it virtually, using a 3-Dmodel. Medical students, for example, frequently study 3-D models of organs andsystems; the models, created from actual samples, provide accuraterepresentations of different conditions. While more complicated to create thanmodels of small objects, a 3-D map of a location can be used to createrealistic simulations or enhance virtual environments.

An eLearning module can use a 3-D model to test learners’ ability toidentify parts of an object or to solicit suggestions for improvements to thedesign of a component; a 3-D map or elevation model can be used in eLearning toteach employees—park rangers or smoke jumpers, for example—the features ofterrain where they will perform their work. Practicing and honing skills using 3-Dmodels can be a cost-effective way to engage learners in realistic training andsimulation exercises and improve overall performance.