In this article, the Vuforia Object Tracking methods; Model Targets, Object Targets, and Model Targets created from 3D scans are introduced and compared. Each feature has advantages in certain use cases, and each are created with different tools. Choose the method best suitable for your use case.
The three ways of implementing Object Tracking carry their own advantages and limitations and they are intended to be used in specific use cases.
- Object Targets: Are created by scanning a physical object. They are a good option for toys and other products with rich surface details and a consistent shape.
- Model Targets: Allow you to recognize objects by shape using pre-existing 3D models. Place AR content on a wide variety of items like industrial equipment, vehicles, toys, and home appliances.
- Model Targets from a 3D scan: Are Model Targets generated from 3D scans and are especially useful when a CAD model is not available.
Each of the three methods require their own set of prerequisites:
Object Targets use the Vuforia Object Scanner to scan the physical object from all its sides and when the object is placed on the printed object scanning image. The scanning process requires a neutral surroundings/environment. The generated object data file (*.od) is then uploaded to the Vuforia Target Manager where a device database can be generated.
To learn more on supported object for Object Targets, please see Object Targets Supported Objects.
Model Targets require the CAD model and its physical counterpart. The CAD model is imported into the Model Target Generator (MTG). In some cases, it may be first prepared in a modelling software. A variety of formats are supported and the MTG allows for setting up which sides the object should be recognized from.
Model Targets from a 3D scan are created from the physical object. Two options are available to scan an object.
- Through a hardware aided structure scanner.
- From high quality images of the physical object in its entirety. Additionally, a photogrammetry software tool is required for post processing of the images.
Both methods will produce a mesh that needs to be cleaned up and perhaps simplified in a modelling software before the digital model is ready to be imported into the MTG.
For more information on supported formats and supported objects for Model Targets, please see Model Targets Supported Objects and CAD Model Best Practices.
Picking an Object Tracking Method
The following section presents some limitations and descriptions that may aid you in your choice to pick the best object tracking method for your particular object and use case. We also encourage you to experiment with each feature and see for yourself which works best.
This method works best for smaller, toy-sized objects that have a feature-rich texture. Detection is based on the physical appearance of the object, so this technology is very sensitive to different textures or color variations between objects.
Object Targets are created with the Vuforia Object Scanner and the corresponding object scanning image target. The image should not be scaled when printed as this would distort the size of your resulting Object Target, which is a limitation to what can fit on the marked area of the image.
Object Targets do not provide a mesh that can be used for authoring or occlusion.
Compared to Model Targets, Object Targets have lower performance requirements.
Model Targets work well in many different environments and for many types of objects due to Vuforia’s capabilities in edge and physical feature tracking. We recommend using Model Targets for industrial settings, tools, medicinal equipment, reflective objects, and cars. In addition, Model Target detection and tracking is based on the shape of the object and therefore also works if the object is not well textured or its appearance varies – e.g. different colors in cars or different textures for tools or toys.
With the Model Target Generator you can define your Model Target to be tracked from different angles with Guide Views or training it for a 360-degree detection range.
Compared to a Model Target made from a 3D scan, a ready CAD model that is true to the physical object is faster and easier to work with as you avoid mismatches that is sometimes introduced from the scanning approach. For example, lighting and shadows on the object can be transferred while scanning, or some reflective and transparent materials won’t be picked up by the scanner.
Model Targets from a 3D scan
If no CAD data is available for a Model Target, a mesh can be created from a 3D scan. Ideally, this is done using hardware aided scanning as it allows scanning of objects even if the target is not well textured. As an alternative, you can also achieve a mesh using photogrammetric model generation. However, this will require your model to be somewhat well textured.
Compared to an Object Target created with the Vuforia Object Scanner, an Object Target might yield a better result in cases where objects are consistent and highly textured. Creating a Model Target using photogrammetry has some advantages though, such as having a mesh representation of your object for authoring and occlusion. Also, in cases where your object is highly textured, but texture varies significantly between objects (e.g. for wooden objects), Model Targets will give better results.
Another advantage of scanning objects is that you are not restricted by their size. Both Model Targets and Model Targets from a scan support immovable objects that you move around or approach only from one side.
We have summarized some of the traits each object tracking feature have in the following table
For smaller objects with a rich texture.
Examples include toys, and small, well textured appliances.
Suitable for objects with corresponding CAD Models.
Examples include 3D printed objects, cars, equipment, tools, industrial objects, all with or without texture.
|Model Targets from a 3D Scan||
Useful when a CAD model is not available of the object. Examples include industrial objects or equipment, wooden objects, statues.
Non-reflective and dark matte objects may not work well.
Hardware aided scans are recommended over photogrammetric scans.