Lesson: Exercise: Using Vuforia - VuMarks

Overview: 
Learn about the Vuforia vision API and how to locate and identify VuMarks.
Objectives: 

Understand of how to use Vuforia to locate VuMarks.

Content: 

Vuforia is a library of classes included in the FTC SDK that supports using the RC phone camera to locate objects in the cameras field of view and return actionable information to your program. That information may allow your robot to locate and navigate to a visual target, locate an object or recognize images. In this lesson we are focusing on a feature of Vuforia called VuMarks. A VuMark is an image that is like a bar code. Contained in the image is encoded information. For instance, in the Relic Revcovery game, the temple images might look identical but each has identifying information (left, right and center) encoded in hexagonal dots. Vuforia can be used to detect the VuMark images when in the camera field of view and read the encoded information and return it to your program. Your program can then determine the relic stacking scheme to gain the most points.

There are several examples in the FTC SDK examples section, but here is a simplified example. This example makes the VuMark finding code generic, meaning it can be used for any VuMark, and puts that code in its own class. This makes the opMode itself simple, it just looks for a VuMark and when found, converts the VuMarks id information to the form (enum) used by the Relic Recovery game. The example also shows X (left/right), Y (up/down) and Z (distance) offsets of the center of the Vumark image in relation to the center of the camera field of view.

 

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