How to assign a tag to spatial mapping surface

Brainy

Hi,
i'm building an application using Unity3d, i'd like to know if is there a way to assign a tag to the spatial mapping gameobject? I need to recognize it during the raycast.

Thank you

Marco

ahillier

Hi @Brainy,
If you want to use tags, then you have to create the tag in the editor first, as you cannot create a new tag during runtime. In general, the 'name' field is a better option. See this unity forum post for more information.

However, when using raycasts, layers are the preferred approach. With layers, you can raycast to a specific layer (such as the 'SpatialMapping' layer), or to a combination of layers.

If you did our Holograms 101 course, we set Layer 31 to be the spatial mapping layer, and all newly created spatial mapping meshes are assigned that layer. We can then perform a raycast against only that layer when we are placing objects on real-world surfaces (example below is from 'TapToPlaceParent.cs'):

        if (placing)
        {
            // Do a raycast into the world that will only hit the Spatial Mapping mesh.
            var headPosition = Camera.main.transform.position;
            var gazeDirection = Camera.main.transform.forward;

            RaycastHit hitInfo;
            if (Physics.Raycast(headPosition, gazeDirection, out hitInfo,
                30.0f, SpatialMapping.PhysicsRaycastMask))
            {
                // Do stuff...
            }
        }

If you're using the prefab from HoloToolkit or the Holograms 230 course, it names each mesh coming from the HoloLens with the prefix 'Surface-' (Surface-0, Surface-1, Surface-2, etc) and assigns each mesh to layer 31. So, if you only want to do a single raycast across multiple layers (including the spatial mapping layer), then you would need to check either the layer, or the name of the gameObject that was hit, to see if it belongs to the spatial mapping mesh before decided how to respond to the raycast hit.

ahillier

Hi @Brainy,
If you want to use tags, then you have to create the tag in the editor first, as you cannot create a new tag during runtime. In general, the 'name' field is a better option. See this unity forum post for more information.

However, when using raycasts, layers are the preferred approach. With layers, you can raycast to a specific layer (such as the 'SpatialMapping' layer), or to a combination of layers.

If you did our Holograms 101 course, we set Layer 31 to be the spatial mapping layer, and all newly created spatial mapping meshes are assigned that layer. We can then perform a raycast against only that layer when we are placing objects on real-world surfaces (example below is from 'TapToPlaceParent.cs'):

        if (placing)
        {
            // Do a raycast into the world that will only hit the Spatial Mapping mesh.
            var headPosition = Camera.main.transform.position;
            var gazeDirection = Camera.main.transform.forward;

            RaycastHit hitInfo;
            if (Physics.Raycast(headPosition, gazeDirection, out hitInfo,
                30.0f, SpatialMapping.PhysicsRaycastMask))
            {
                // Do stuff...
            }
        }

If you're using the prefab from HoloToolkit or the Holograms 230 course, it names each mesh coming from the HoloLens with the prefix 'Surface-' (Surface-0, Surface-1, Surface-2, etc) and assigns each mesh to layer 31. So, if you only want to do a single raycast across multiple layers (including the spatial mapping layer), then you would need to check either the layer, or the name of the gameObject that was hit, to see if it belongs to the spatial mapping mesh before decided how to respond to the raycast hit.