diff --git a/ClumsyPilot/ParkrobTrajplanner/tarjplanner_movementtest/TrajectoryObservationPresentation.cs b/ClumsyPilot/ParkrobTrajplanner/tarjplanner_movementtest/TrajectoryObservationPresentation.cs
index 8a6c6f9..14e52d6 100644
--- a/ClumsyPilot/ParkrobTrajplanner/tarjplanner_movementtest/TrajectoryObservationPresentation.cs
+++ b/ClumsyPilot/ParkrobTrajplanner/tarjplanner_movementtest/TrajectoryObservationPresentation.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.Drawing;
 using System.Globalization;
 using ClumsyCore;
@@ -36,6 +37,46 @@ public static class TrajectoryObservationPresentationText
     }
 }
 
+public sealed class TrajectoryObservationLsPresentationPoint
+{
+    public TrajectoryObservationLsPresentationPoint(double horizontalPathS, double verticalLateralOffset)
+    {
+        HorizontalPathS = horizontalPathS;
+        VerticalLateralOffset = verticalLateralOffset;
+    }
+
+    public double HorizontalPathS { get; }
+
+    public double VerticalLateralOffset { get; }
+}
+
+public sealed class TrajectoryObservationLsPresentationModel
+{
+    private TrajectoryObservationLsPresentationModel(IReadOnlyList<TrajectoryObservationLsPresentationPoint> samples)
+    {
+        Samples = new ReadOnlyCollection<TrajectoryObservationLsPresentationPoint>(
+            new List<TrajectoryObservationLsPresentationPoint>(samples));
+    }
+
+    public string HorizontalAxisLabel => "path-S (m)";
+
+    public string VerticalAxisLabel => "lateral offset (m)";
+
+    public IReadOnlyList<TrajectoryObservationLsPresentationPoint> Samples { get; }
+
+    public static TrajectoryObservationLsPresentationModel Create(TrajectoryObservationCharts charts)
+    {
+        if (charts == null) throw new ArgumentNullException(nameof(charts));
+        var samples = new List<TrajectoryObservationLsPresentationPoint>(charts.LsSamples.Count);
+        for (int index = 0; index < charts.LsSamples.Count; index++)
+        {
+            TrajectoryObservationLsSample sample = charts.LsSamples[index];
+            samples.Add(new TrajectoryObservationLsPresentationPoint(sample.PathS, sample.LateralOffset));
+        }
+        return new TrajectoryObservationLsPresentationModel(samples);
+    }
+}
+
 public sealed class TrajectoryObservationPresentation
 {
     private const float MillimetersPerMeter = 1000f;
@@ -82,17 +123,21 @@ public sealed class TrajectoryObservationPresentation
             return;
         }
 
+        TrajectoryObservationLsPresentationModel model = TrajectoryObservationLsPresentationModel.Create(charts);
         float maxS = MaximumPathS(charts.LsSamples);
         float maxL = MaximumLateralOffset(charts.LsSamples);
-        lsPainter.DrawLine(Color.Gainsboro, -maxL, 0f, maxL, 0f, width: 2);
-        lsPainter.DrawLine(Color.Gainsboro, 0f, 0f, 0f, maxS, width: 2);
-        lsPainter.DrawText(Color.White, "L-S (lateral offset / path-S)", -maxL, maxS + 150f);
-        for (int index = 1; index < charts.LsSamples.Count; index++)
+        lsPainter.DrawLine(Color.Gainsboro, 0f, 0f, maxS, 0f, width: 2);
+        lsPainter.DrawLine(Color.Gainsboro, 0f, -maxL, 0f, maxL, width: 2);
+        lsPainter.DrawText(Color.White, "S-L", maxS + 100f, maxL + 150f);
+        lsPainter.DrawText(Color.White, model.HorizontalAxisLabel, maxS + 100f, -200f);
+        lsPainter.DrawText(Color.White, model.VerticalAxisLabel, 100f, maxL + 300f);
+        for (int index = 1; index < model.Samples.Count; index++)
         {
-            TrajectoryObservationLsSample previous = charts.LsSamples[index - 1];
-            TrajectoryObservationLsSample current = charts.LsSamples[index];
-            lsPainter.DrawLine(Color.MediumPurple, ToMillimeters(previous.LateralOffset), ToMillimeters(previous.PathS),
-                ToMillimeters(current.LateralOffset), ToMillimeters(current.PathS), width: 3);
+            TrajectoryObservationLsPresentationPoint previous = model.Samples[index - 1];
+            TrajectoryObservationLsPresentationPoint current = model.Samples[index];
+            lsPainter.DrawLine(Color.MediumPurple, ToMillimeters(previous.HorizontalPathS),
+                ToMillimeters(previous.VerticalLateralOffset), ToMillimeters(current.HorizontalPathS),
+                ToMillimeters(current.VerticalLateralOffset), width: 3);
         }
     }
 
diff --git a/ClumsyPilot/tests/EMPlannerVerificationHost/TrajectoryObservationChecks.cs b/ClumsyPilot/tests/EMPlannerVerificationHost/TrajectoryObservationChecks.cs
index 3c83ba5..3c57f92 100644
--- a/ClumsyPilot/tests/EMPlannerVerificationHost/TrajectoryObservationChecks.cs
+++ b/ClumsyPilot/tests/EMPlannerVerificationHost/TrajectoryObservationChecks.cs
@@ -18,6 +18,7 @@ internal static class TrajectoryObservationChecks
         RejectsObstacleOutsideConfiguredBounds();
         VerifiesLsAndStUsePublishedTrajectoryData();
         VerifiesPresentationTextDescribesObservationWithoutSendingCommand();
+        VerifiesLsPresentationUsesPathSOnHorizontalAxis();
         VerifiesRollingRequestUsesOnePublishedTrajectorySnapshot();
         FreezesBootstrapVehicleForRollingRequests();
     }
@@ -155,6 +156,22 @@ internal static class TrajectoryObservationChecks
             "observer presentation LS projection failures");
     }
 
+    private static void VerifiesLsPresentationUsesPathSOnHorizontalAxis()
+    {
+        TrajectoryObservationCharts charts = TrajectoryObservationCharts.Build(
+            CreatePublishedTrajectory(new DateTimeOffset(2026, 8, 4, 0, 0, 0, TimeSpan.Zero)),
+            CreateStraightSegment(), 0.5d);
+
+        TrajectoryObservationLsPresentationModel model = TrajectoryObservationLsPresentationModel.Create(charts);
+
+        Verification.Equal("path-S (m)", model.HorizontalAxisLabel, "observer LS horizontal axis label");
+        Verification.Equal("lateral offset (m)", model.VerticalAxisLabel, "observer LS vertical axis label");
+        Verification.NearlyEqual(10.25d, model.Samples[0].HorizontalPathS,
+            "observer LS path-S is horizontal");
+        Verification.NearlyEqual(0.10d, model.Samples[0].VerticalLateralOffset,
+            "observer LS lateral offset is vertical");
+    }
+
     private static void FreezesBootstrapVehicleForRollingRequests()
     {
         DateTimeOffset effectiveAt = new DateTimeOffset(2026, 8, 4, 2, 0, 0, TimeSpan.Zero);