Question Turn Off MARS Camera

Hi there! Turning off the physical camera should be pretty straightforward. This doesn't happen automatically when you disable the MARSSession object, but you can write a simple script to call `IUsesSessionControl.PauseSession` to do it.

I've provided a sample script here which includes methods to pause/resume/reset the session. Hope this helps!

 

Sorry, I should have been more clear. You aren't meant to call `IUsesSessionControl.PauseSession` directly, but rather use it as an extension method on something which implements `IUsesSessionControl`. Then you would call `this.PauseSession()` from that script.

It's easiest to have this script exist in the scene before it is loaded, in which case MARS takes care of setting the `.provider` property. If you need to create this object in code, it should also implement `IUsesFunctionalityInjection` and call `this.EnsureFunctionalityInjected()` in Awake.

 

Kind of

What you posted seems like it _should_ work, but I was talking about having this all be one script. The "Hidden subscriber" pattern used in the example is also a bit more complicated than what you need here. I haven't been able to test this, but the following code should work, as long as you don't call `TogglePaused` until the camera has fully initialized. If you want the app to _start_ with the camera disabled, you can do that by disabling auto-load in XR Management settings. Happy to go into more detail there if that's what you're after.

Please try this and see if it works for you

Code (CSharp):

1. using System;
2. using Unity.MARS.Providers;
3. using Unity.MARS.Settings;
4. using Unity.XRTools.ModuleLoader;
5. using UnityEngine;
6.  
7. namespace Unity.MARS
8. {
9.     public class SessionUI : MonoBehaviour, IUsesFunctionalityInjection, IUsesSessionControl
10.     {
11.         IProvidesFunctionalityInjection IFunctionalitySubscriber<IProvidesFunctionalityInjection>.provider { get; set; }
12.         IProvidesSessionControl IFunctionalitySubscriber<IProvidesSessionControl>.provider { get; set; }
13.  
14.         void Awake()
15.         {
16.             // Only necessary if this script isn't already in the scene when you press Play
17.             this.EnsureFunctionalityInjected();
18.         }
19.  
20.         public void TogglePaused()
21.         {
22.             var marsCore = MARSCore.instance;
23.             var wasPaused = marsCore.paused;
24.             marsCore.paused = !wasPaused;
25.             if (wasPaused)
26.             {
27.                 this.ResumeSession();
28.             }
29.             else
30.             {
31.                 this.PauseSession();
32.             }
33.         }
34.     }
35. }
36.  

 

Hi there! Thanks for using MARS

I'll try to answer your questions inline below

Unfortunately, this isn't really possible, at least not if you want full 6dof tracking. You can disable the `ARCameraBackground` which should get you some GPU performance back, but the phone still needs the camera to be powered on and recording images in order to do SLAM which is responsible for positional tracking.

It would be possible to use something like the Gyroscope.attitude API (https://docs.unity3d.com/ScriptReference/Gyroscope-attitude.html) to just do 3dof tracking while AR tracking is paused, if that is sufficient.

I'll answer (2-2) first: the main camera transform update happens every frame. Some other parts of the query pipeline, like updating face poses and landmarks also happen every frame _once the query match has occurred_. Essentially, the evaluation interval only affects the timing of query acquisition and loss. Once a query match is acquired, updates to the data should happen once per frame, regardless of evaluation interval or calls to `RequestSceneEvaluation`.

Setting scene evaluation to WaitForRequest and calling RequestSceneEvaluation every frame is equivalent to setting the interval to 0 and leaving the default Evaluate On Interval setting at start-up. Because of the pipelined nature of the MARS backend, it is not possible to get matches to happen immediately on the frame that the data is available. There will always be a delay of a few frames depending on what stage of the pipeline is active. It is not possible to run multiple pipeline stages at once.

Finally, yes there will be a performance impact to setting the evaluation interval to 0 or trying to evaluate every frame. Depending on your use case, this may be acceptable. If you only expect users to scan a small number of surfaces and don't make heavy use of synthetic objects, evaluating every frame may work well. The other thing to keep in mind is that query acquisition causes objects to appear and disappear by default. A slow evaluation interval keeps things from "popping" in and out as matches are acquired and lost due to query constraints. We have found that keeping the evaluation interval a little slower leads to a better user experience. But, of course, your mileage may vary

Hope this helps!