A Model Target requires that the user hold their device at a particular angle relative to the object, and at a particular distance to initialize tracking of a Model Target. To aid with this process, your app will typically draw an image showing an approximation of the object from this distance and viewing angle, so that the user just needs to move their device until the object matches the image. When they do this, tracking can begin.
In Vuforia Engine, both the image and the particular angle/distance relative to the object that image represents is called a Guide View.
For an indication of how Guide Views work within a typical Model Target application, see Introduction to Model Targets in Unity and the Model Target Test App User Guide.
Guide Views in Advanced Model Target Databases
By using Advanced Model Targets in your application, you are able to detect and track one out of several different objects (one active at a time), or you may want to have multiple Advanced Guide Views for a single object with a certain recognition range (for example, if you have a very large object and you want to provide a different user experience depending on which side the user approaches the object from).
Therefore, the Model Target Generator allows you to define multiple Guide Views per Model Target, and/or merge multiple Model Target databases together through a cloud-based training process that outputs a single Advanced Model Target Database.
NOTE: For applications using the Advanced Model Target feature, we recommend displaying a search-frame or similar UX to indicate visually that the application is actively searching for one or more objects as Advanced Guide Views are by default not shown on the screen during runtime.
For more information, see Model Target Guide View and Advanced Model Target Databases.