Chapter 2

Natural-Feature Tracking and Visual Search


  • An introduction to natural-feature tracking
  • An introduction to visual search

In this chapter, you will learn about natural-feature tracking, which expands on the concept of the marker and enables 3D objects to be overlaid on top of real images (such as book covers, CD covers, or even your own holiday snapshots). You will also learn about visual search, which is similar to natural-feature tracking except a different action takes place when an image has been recognized. Before you begin, you’ll need an Android or an iPhone.


Unlike AR solutions that use markers as their basis for recognition, natural-feature tracking solutions can be applied to almost any image as long as the image is complex enough. An example of a natural-feature tracking application is a mobile application that can recognize a movie poster. With natural-feature tracking, the application can analyze the poster and identify it by comparing the poster image to similar images. In contrast, a marker-based solution requires a special identifier to be included on the poster; it would be the marker that provides the identification rather than the poster image.

Markerless solutions make a better solution for a couple of reasons. Markers and QR codes are not user-friendly and you would have a difficult task persuading the marketing people behind the latest Hollywood blockbuster to include such content with ...

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