diff --git a/OpenRA.Mods.Common/ActorInitializer.cs b/OpenRA.Mods.Common/ActorInitializer.cs
index 66614467b2..b8ba2a5c67 100644
--- a/OpenRA.Mods.Common/ActorInitializer.cs
+++ b/OpenRA.Mods.Common/ActorInitializer.cs
@@ -23,6 +23,12 @@ namespace OpenRA.Mods.Common
 			: base(value) { }
 	}
 
+	public class TerrainOrientationInit : ValueActorInit<WRot>, ISingleInstanceInit
+	{
+		public TerrainOrientationInit(WRot value)
+			: base(value) { }
+	}
+
 	public class CreationActivityDelayInit : ValueActorInit<int>, ISingleInstanceInit
 	{
 		public CreationActivityDelayInit(int value)
diff --git a/OpenRA.Mods.Common/Graphics/ActorPreview.cs b/OpenRA.Mods.Common/Graphics/ActorPreview.cs
index 6732ffecf4..afca3a4fe9 100644
--- a/OpenRA.Mods.Common/Graphics/ActorPreview.cs
+++ b/OpenRA.Mods.Common/Graphics/ActorPreview.cs
@@ -67,20 +67,32 @@ namespace OpenRA.Mods.Common.Graphics
 			if (facingInfo == null)
 				return () => WRot.None;
 
+			WAngle facing;
+
 			// Dynamic facing takes priority
 			var dynamicInit = reference.GetOrDefault<DynamicFacingInit>();
 			if (dynamicInit != null)
 			{
-				// TODO: Account for terrain slope
 				var getFacing = dynamicInit.Value;
-				return () => WRot.FromYaw(getFacing());
+				facing = getFacing();
+			}
+			else
+			{
+				// Fall back to initial actor facing if an Init isn't available
+				var facingInit = reference.GetOrDefault<FacingInit>();
+				facing = facingInit != null ? facingInit.Value : facingInfo.GetInitialFacing();
 			}
 
-			// Fall back to initial actor facing if an Init isn't available
-			var facingInit = reference.GetOrDefault<FacingInit>();
-			var facing = facingInit != null ? facingInit.Value : facingInfo.GetInitialFacing();
-			var orientation = WRot.FromYaw(facing);
-			return () => orientation;
+			var mobileInfo = Actor.TraitInfoOrDefault<MobileInfo>();
+			var location = reference.GetOrDefault<LocationInit>();
+			if (location == null || mobileInfo == null || mobileInfo.TerrainOrientationAdjustmentMargin.Length < 0)
+				return () => WRot.FromYaw(facing);
+
+			var orientationInit = reference.GetOrDefault<TerrainOrientationInit>();
+			var terrainOrientation = orientationInit != null ? orientationInit.Value : World.Map.TerrainOrientation(location.Value);
+			var terrainAdjustedFacing = new WRot(new WVec(0, 0, 1024).Rotate(terrainOrientation), facing);
+
+			return () => terrainOrientation + terrainAdjustedFacing;
 		}
 
 		public Func<WAngle> GetFacing()
diff --git a/OpenRA.Mods.Common/Traits/World/EditorActorPreview.cs b/OpenRA.Mods.Common/Traits/World/EditorActorPreview.cs
index 5bd1393485..6f198e6bfb 100644
--- a/OpenRA.Mods.Common/Traits/World/EditorActorPreview.cs
+++ b/OpenRA.Mods.Common/Traits/World/EditorActorPreview.cs
@@ -47,6 +47,7 @@ namespace OpenRA.Mods.Common.Traits
 		readonly TooltipInfoBase tooltip;
 		IActorPreview[] previews;
 		readonly ActorReference reference;
+		readonly Action<CPos> onCellEntryChanged;
 		readonly Dictionary<INotifyEditorPlacementInfo, object> editorData = new();
 
 		public EditorActorPreview(WorldRenderer worldRenderer, string id, ActorReference reference, PlayerReference owner)
@@ -98,6 +99,9 @@ namespace OpenRA.Mods.Common.Traits
 
 			SelectionBox = new SelectionBoxAnnotationRenderable(new WPos(CenterPosition.X, CenterPosition.Y, 8192),
 				new Rectangle(Bounds.X, Bounds.Y, Bounds.Width, Bounds.Height), Color.White);
+
+			// TODO: updating all actors on the map is not very efficient.
+			onCellEntryChanged = _ => GeneratePreviews();
 		}
 
 		public void Tick()
@@ -134,12 +138,17 @@ namespace OpenRA.Mods.Common.Traits
 		{
 			foreach (var notify in Info.TraitInfos<INotifyEditorPlacementInfo>())
 				editorData[notify] = notify.AddedToEditor(this, worldRenderer.World);
+
+			// TODO: this should subscribe to ramp cell map as well.
+			worldRenderer.World.Map.Height.CellEntryChanged += onCellEntryChanged;
 		}
 
 		public void RemovedFromEditor()
 		{
 			foreach (var kv in editorData)
 				kv.Key.RemovedFromEditor(this, worldRenderer.World, kv.Value);
+
+			worldRenderer.World.Map.Height.CellEntryChanged -= onCellEntryChanged;
 		}
 
 		public void AddInit<T>(T init) where T : ActorInit