With object detection, 3d objects can be placed on real elements from your physical environment by recognizing the outline shape.

For the detection model there are a few requirements:

• A Frontline scene must be created, if it hasn't yet, refer to Importing your 3d model
• A detection object model - must be under 20k polygons, and made of under 10 parts. it can be the whole model, or any part of it that is distinguishable for easy detection (example: a bright area with a defined shape and not a white cube)
• The main model transforms (position, rotation, scale) should be exactly as the Root object in the scene. 

Steps to add object detection:

1. After we have our detection model, right click on it in the hierarchy window, go to LLS > create > object tracking manager. This creates multiple objects in our scene to help with object detection. These objects must remain untouched.

2. Now we need to define a visual frame position to set where to object detection will start with:
2a. Choose a location that is logical to where the user will stand relative to the real life element.
2b. Then select the Testing camera rotation object, under object tracking manager. Click control shift F to snap it to your current view.
2c. after that, do the same to the testing camera distance object. you should be able to see the camera view in a small thumbnail.

3. After we have everything set, we need to build a file for Hololens, android or any other available platform that supports mixed reality.

4. To test this, in your chosen platform, open the 3d item, and select the AR mod, select the "Object Detection" option and try to adjust the camera over the physical object in your room / environment.

The virtual object should snap and overlay on the physical one

Adding a Secondary Mixed Reality Object Detection While In a Procedure

1. First create the object detection by right clicking on the relevant optimized model, select LLS > Create > Object tracking manager.
2. While selecting the new Object tracking manager, Make sure it is not a Main tracker, then connect the Model that you want to anchor the tracking to, into the root field. Do this by finding the relevant model under the model's hierarchy, then drag it to the Object Tracking Manager Root field.
3. Then, we need to create an Interaction that will trigger the Object Tracking mode, we can do this by creating an Interaction through the Interaction menu.
4. Give it a name, for example the model's name and add a Tracking after it, so it could be easily found later.
5. Now that we have both the Object Detection Manager and the Tracking Interaction, in the interaction, add a new event in the "On Activate' field, Drag the Object tracking manager into the field, and select Object Tracking Manager, Set Sub Object Tracking state, make sure its on. This will tell the interaction to go into the tracking mode using the selected Object Tracking Manager.
6. To deactivate the Tracker so the application goes back to the main tracking mode of the machine, find the interaction where the tracked part is going back to the machine, usually it is the interaction that takes the part off of the machine, played in reverse.
   Then on the 'On Activate' field create a new event, and drag the Object tracking manager into the field.
   For the event, select Object Tracking Manager, and Set Sub Object Tracking state. Tick it off.
   Now, when returning the part back into the machine, the application will know it should show the user the Tracking mode of the entire machine, which is the main tracker.
7. Upload the interaction, and we are done on the Unity side.
8. To add the interaction into the flow, open the procedure in the node editor, then add a new node, and add the created interaction into it.
9. Usually you would want the tracking mode done only in AR devices, so can decide which platform will show the tracking interaction, by adding a platform switch node, then dragging the AR options into the tracking interaction, and the None AR options into the next step without Tracking.
10. After tracking you would want to continue to the next steps, drag the Tracking interaction to the next step.
11. Save and publish the procedure, and test the Tracking in the app through AR.

Troubleshooting:

Hololens build does not exist in Frontline builder
Cause: Hololens module is not installed in Unity.
Install it through Unity Hub under the name "Universal Windows Platform build Support", refer to installing Unity for more information.

After creating the Object Tracking Manager it is empty.

Solution: Check that the following are correct:

1. In the object called UIData, find the category called "Scene data", if the values there are empty or none, that means your scene is corrupt and you need to create it again

2. You have to create the tracking manager while selecting your detection model.

3. Remove any Object tracking manager and Placer objects in your scene before creating a new one.

I want to change the object detection model after setting it up

Solution: In order to change it, you need to first remove it entirely from your scene:

1. Remove from the scene the following objects: ObjectTrackingManager, Placer.

2. Now import the new detection object to scene, and create a new object tracking manager on it.

Object detection is offset
cause 1: models are not in center of world, make sure that your main model object and Root object are in the center of the world, and have the same position, rotation and scale values.
cause 2: models under ObjectTrackingManager or Placer are not exactly aligned with the main model:

1. Turn on mesh renderer on the object detection model under ObjectTrackingManager, check that it has the correct position with the main model, then disable the mesh renderer component again.

2. Do the same for the object detection model under Placer object.