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+# TSDF2D Support - Implementation Plan
+
+**Status:** ✅ **IMPLEMENTATION COMPLETED** - All phases implemented with comprehensive unit tests
+
+## 📋 Tổng Quan
+
+TSDF (Truncated Signed Distance Function) 2D là một loại grid khác ngoài ProbabilityGrid cho 2D SLAM. TSDF lưu trữ:
+- **TSD (Truncated Signed Distance)**: Khoảng cách có dấu tới bề mặt, được truncate trong phạm vi `[-truncation_distance, truncation_distance]`
+- **Weight**: Trọng số của measurement, sử dụng để tích hợp nhiều measurements
+
+**Ưu điểm của TSDF so với ProbabilityGrid:**
+- Hỗ trợ subpixel accuracy tốt hơn
+- Xử lý uncertainty tốt hơn với weighted integration
+- Có thể extract surface với độ chính xác cao hơn
+
+---
+
+## 🎯 Components Cần Implement
+
+### 1. **TSDValueConverter** (Core Utility)
+### 2. **TSDF2D Grid** (Grid Implementation)
+### 3. **TSDFRangeDataInserter2D** (Range Data Inserter)
+### 4. **NormalEstimation2D** (Normal Estimation Utility)
+### 5. **InterpolatedTSDF2D** (Interpolation for Scan Matching)
+### 6. **TSDFMatchCostFunction2D** (Ceres Cost Function)
+### 7. **Proto Definitions** (Configuration & Serialization)
+
+---
+
+## 📝 Chi Tiết Implementation
+
+### Phase 1: Core Utilities
+
+#### 1.1 TSDValueConverter
+**File:** `Mapping/Internal/2D/TSDValueConverter.cs`
+
+**Purpose:** Convert giữa TSD/Weight values và ushort values để lưu trữ hiệu quả trong grid.
+
+**Methods cần implement:**
+```csharp
+public class TSDValueConverter
+{
+    public TSDValueConverter(float maxTSD, float maxWeight, ValueConversionTables conversionTables);
+    
+    // TSD conversion
+    public ushort TSDToValue(float tsd);
+    public float ValueToTSD(ushort value);
+    public float GetMinTSD();
+    public float GetMaxTSD();
+    public ushort GetUnknownTSDValue();
+    public ushort GetUpdateMarker();
+    
+    // Weight conversion
+    public ushort WeightToValue(float weight);
+    public float ValueToWeight(ushort value);
+    public float GetMinWeight();
+    public float GetMaxWeight();
+    public ushort GetUnknownWeightValue();
+}
+```
+
+**Key Implementation Details:**
+- TSD được lưu trong `correspondence_cost_cells` như ProbabilityGrid
+- Highest bit (bit 15) của TSD value là update marker
+- Weight được lưu trong separate `weight_cells` array
+- Sử dụng lookup tables từ `ValueConversionTables` để convert hiệu quả
+
+**C++ Reference:** `refs/cartographer/cartographer/mapping/internal/2d/tsd_value_converter.h/cc`
+
+---
+
+#### 1.2 NormalEstimation2D
+**File:** `Mapping/Internal/2D/NormalEstimation2D.cs`
+
+**Purpose:** Estimate surface normals từ range data để tính toán SDF distance accurately.
+
+**Methods cần implement:**
+```csharp
+public static class NormalEstimation2D
+{
+    // Estimate normals for sorted range data
+    public static List<float> EstimateNormals(
+        RangeData sortedRangeData,
+        NormalEstimationOptions2D options);
+    
+    // Helper: Get normal angle at index
+    private static float GetNormalAngle(int index, ...);
+}
+```
+
+**Key Implementation Details:**
+- Range data phải được sort theo angle từ origin (sử dụng `RangeDataSorter`)
+- Normal được estimate từ các points lân cận (trong `sample_radius`)
+- Normal được trả về dưới dạng angle (radians) cho mỗi hit point
+- Sử dụng `num_normal_samples` để average normals
+
+**C++ Reference:** `refs/cartographer/cartographer/mapping/internal/2d/normal_estimation_2d.h/cc`
+
+**Proto:** `Proto/Mapping/NormalEstimationOptions2DProto.cs` (đã có proto definition)
+
+---
+
+### Phase 2: TSDF2D Grid
+
+#### 2.1 TSDF2D Grid Class
+**File:** `Mapping/2D/TSDF2D.cs`
+
+**Inheritance:** `TSDF2D : Grid2D`
+
+**Key Properties:**
+- `List<ushort> _weightCells` - Separate weight grid
+- `TSDValueConverter _valueConverter` - TSD/Weight converter
+- `ValueConversionTables _conversionTables` - Lookup tables
+
+**Methods cần implement:**
+```csharp
+public class TSDF2D : Grid2D
+{
+    public TSDF2D(MapLimits limits, float truncationDistance, float maxWeight, 
+                  ValueConversionTables conversionTables);
+    public TSDF2D(Proto.Mapping.Grid2D proto, ValueConversionTables conversionTables);
+    
+    // Cell accessors
+    public void SetCell(Array2i cellIndex, float tsd, float weight);
+    public float GetTSD(Array2i cellIndex);
+    public float GetWeight(Array2i cellIndex);
+    public (float tsd, float weight) GetTSDAndWeight(Array2i cellIndex);
+    public bool CellIsUpdated(Array2i cellIndex);
+    
+    // Grid2D overrides
+    public override GridType GetGridType() => GridType.TSDF;
+    public override void GrowLimits(Vector2 point);
+    public override Proto.Mapping.Grid2D ToProto();
+    public override Grid2D ComputeCroppedGrid();
+    public override bool DrawToSubmapTexture(...);
+}
+```
+
+**Key Implementation Details:**
+- Constructor: Initialize với `minCorrespondenceCost = -truncationDistance`, `maxCorrespondenceCost = truncationDistance`
+- `SetCell`: 
+  - Check update marker trước khi update
+  - Set update marker (bit 15) vào TSD value
+  - Store TSD trong `_correspondenceCostCells`
+  - Store weight trong `_weightCells`
+- `GetTSD`: Remove update marker và convert từ value về TSD
+- `GetWeight`: Convert từ weight value về float weight
+- `GrowLimits`: Override để grow cả `_correspondenceCostCells` và `_weightCells`
+- `FinishUpdate`: Remove update markers từ TSD cells (đã có trong Grid2D base)
+
+**C++ Reference:** `refs/cartographer/cartographer/mapping/internal/2d/tsdf_2d.h/cc`
+
+---
+
+#### 2.2 TSDF2D Proto Support
+**File:** `Proto/Mapping/Grid2DProto.cs` (update existing)
+
+**Changes needed:**
+- Add `TSDF2D? Tsdf2D { get; set; }` property (nếu chưa có)
+- Update `ToProto()` và constructor trong `TSDF2D` để serialize/deserialize TSDF2D data
+
+**Proto structure:**
+```protobuf
+message TSDF2D {
+  float truncation_distance = 1;
+  float max_weight = 2;
+  repeated int32 weight_cells = 3;
+}
+```
+
+**C++ Reference:** `refs/cartographer/cartographer/mapping/proto/tsdf_2d.proto`
+
+---
+
+### Phase 3: Range Data Inserter
+
+#### 3.1 TSDFRangeDataInserterOptions2D Proto
+**File:** `Proto/Mapping/TSDFRangeDataInserterOptions2DProto.cs` (new file)
+
+**Structure:**
+```csharp
+public struct TSDFRangeDataInserterOptions2D
+{
+    public double TruncationDistance { get; set; }
+    public double MaximumWeight { get; set; }
+    public bool UpdateFreeSpace { get; set; }
+    public NormalEstimationOptions2D NormalEstimationOptions { get; set; }
+    public bool ProjectSdfDistanceToScanNormal { get; set; }
+    public int UpdateWeightRangeExponent { get; set; }
+    public double UpdateWeightAngleScanNormalToRayKernelBandwidth { get; set; }
+    public double UpdateWeightDistanceCellToHitKernelBandwidth { get; set; }
+}
+```
+
+**C++ Reference:** `refs/cartographer/cartographer/mapping/proto/tsdf_range_data_inserter_options_2d.proto`
+
+---
+
+#### 3.2 TSDFRangeDataInserter2D
+**File:** `Mapping/2D/TSDFRangeDataInserter2D.cs`
+
+**Implements:** `IRangeDataInserter`
+
+**Key Methods:**
+```csharp
+public class TSDFRangeDataInserter2D : IRangeDataInserter
+{
+    private readonly TSDFRangeDataInserterOptions2D _options;
+    
+    public TSDFRangeDataInserter2D(TSDFRangeDataInserterOptions2D options);
+    public void Insert(RangeData rangeData, IGrid grid);
+    
+    private void InsertHit(Vector2 hit, Vector2 origin, float normal, TSDF2D tsdf);
+    private void UpdateCell(Array2i cell, float updateSdf, float updateWeight, TSDF2D tsdf);
+    private static void GrowAsNeeded(RangeData rangeData, float truncationDistance, TSDF2D tsdf);
+}
+```
+
+**Key Implementation Details:**
+
+1. **Insert method:**
+   - Cast grid to TSDF2D
+   - Grow grid limits if needed
+   - Sort range data by angle from origin (using `RangeDataSorter`)
+   - Estimate normals if needed (`project_sdf_distance_to_scan_normal` or angle-based weight)
+   - For each hit:
+     - Cast ray from origin to hit
+     - If `update_free_space`: Update cells along ray until `truncation_distance` behind hit
+     - Else: Update cells within `truncation_distance` around hit
+   - Call `FinishUpdate()` on grid
+
+2. **InsertHit method:**
+   - Calculate cells along ray (hoặc around hit)
+   - For each cell:
+     - Compute SDF distance:
+       - If `project_sdf_distance_to_scan_normal`: Project distance to scan normal
+       - Else: Use Euclidean distance from cell to hit
+     - Compute update weight:
+       - Base weight: `1.0 / distance^update_weight_range_exponent`
+       - Angle weight: Gaussian kernel based on angle between scan normal and ray
+       - Distance weight: Gaussian kernel based on distance from cell to hit
+     - Call `UpdateCell`
+
+3. **UpdateCell method:**
+   - Get current TSD and weight: `(currentTSD, currentWeight) = tsdf.GetTSDAndWeight(cell)`
+   - Compute new TSD: Weighted average
+     - `newTSD = (currentTSD * currentWeight + updateSdf * updateWeight) / (currentWeight + updateWeight)`
+     - Clamp to `[-truncation_distance, truncation_distance]`
+   - Compute new weight: `newWeight = min(currentWeight + updateWeight, maxWeight)`
+   - Call `tsdf.SetCell(cell, newTSD, newWeight)`
+
+4. **GrowAsNeeded:**
+   - Similar to ProbabilityGrid inserter
+   - Include truncation distance when calculating bounding box
+
+**Helper Functions:**
+```csharp
+// Gaussian kernel for weight calculation
+private static float GaussianKernel(float x, float sigma)
+{
+    return 1.0f / (Math.Sqrt(2.0 * Math.PI) * sigma) * 
+           Math.Exp(-0.5 * x * x / (sigma * sigma));
+}
+
+// Range weight factor: 1.0 / range^exponent
+private static float ComputeRangeWeightFactor(float range, int exponent)
+
+// RangeDataSorter: Sort points by angle from origin
+private class RangeDataSorter : IComparer<RangefinderPoint>
+```
+
+**C++ Reference:** `refs/cartographer/cartographer/mapping/internal/2d/tsdf_range_data_inserter_2d.h/cc`
+
+---
+
+### Phase 4: Scan Matching Support
+
+#### 4.1 InterpolatedTSDF2D
+**File:** `Mapping/Internal/2D/ScanMatching/InterpolatedTSDF2D.cs`
+
+**Purpose:** Bilinear interpolation của TSDF values cho Ceres autodiff.
+
+**Methods:**
+```csharp
+public class InterpolatedTSDF2D
+{
+    private readonly TSDF2D _tsdf;
+    
+    public InterpolatedTSDF2D(TSDF2D tsdf);
+    
+    // Template method for Ceres autodiff
+    public T GetCorrespondenceCost<T>(T x, T y) where T : struct
+    {
+        // Bilinear interpolation of TSD values
+        // Returns MaxCorrespondenceCost if any interpolation point is unknown (weight == 0)
+    }
+    
+    public T GetWeight<T>(T x, T y) where T : struct
+    {
+        // Bilinear interpolation of weight values
+    }
+    
+    private Vector2 CenterOfLowerPixel(double x, double y);
+    private T InterpolateBilinear<T>(T x, T y, float x1, float y1, float x2, float y2, 
+                                      float q11, float q12, float q21, float q22);
+}
+```
+
+**Key Implementation Details:**
+- Get 4 neighboring cells: `(x1,y1)`, `(x1+1,y1)`, `(x1,y1+1)`, `(x1+1,y1+1)`
+- Check weights: If any weight == 0, return `MaxCorrespondenceCost`
+- Interpolate TSD values using bilinear interpolation
+- Works with Ceres Jet types (automatic differentiation)
+
+**C++ Reference:** `refs/cartographer/cartographer/mapping/internal/2d/scan_matching/interpolated_tsdf_2d.h`
+
+---
+
+#### 4.2 TSDFMatchCostFunction2D
+**File:** `Mapping/Internal/2D/ScanMatching/TSDFMatchCostFunction2D.cs`
+
+**Purpose:** Ceres cost function cho TSDF-based scan matching.
+
+**Methods:**
+```csharp
+public static class TSDFMatchCostFunction2D
+{
+    public static CostFunction CreateAutoDiffCostFunction(
+        double scalingFactor,
+        PointCloud pointCloud,
+        TSDF2D grid)
+    {
+        // Create InterpolatedTSDF2D
+        // Return AutoDiffCostFunction with TSDFMatchCostFunctor2D
+    }
+}
+
+private struct TSDFMatchCostFunctor2D
+{
+    private readonly double _scalingFactor;
+    private readonly PointCloud _pointCloud;
+    private readonly InterpolatedTSDF2D _interpolatedTSDF;
+    
+    public void Evaluate(double[] parameters, double[] residuals, double[][] jacobians)
+    {
+        // parameters: [x, y, cos_theta, sin_theta]
+        // Transform each point in pointCloud by pose
+        // For each transformed point:
+        //   residual = scaling_factor * interpolatedTSDF.GetCorrespondenceCost(x, y)
+        // residuals length = pointCloud.Count
+    }
+}
+```
+
+**Key Implementation Details:**
+- Transform point cloud by pose: `R * point + translation`
+- Get interpolated correspondence cost for each transformed point
+- Residual = `scaling_factor * correspondence_cost`
+- Ceres sẽ minimize tổng squared residuals
+
+**C++ Reference:** `refs/cartographer/cartographer/mapping/internal/2d/scan_matching/tsdf_match_cost_function_2d.h/cc`
+
+---
+
+#### 4.3 Update Scan Matchers
+
+**4.3.1 RealTimeCorrelativeScanMatcher2D**
+**File:** `Mapping/Internal/2D/ScanMatching/RealTimeCorrelativeScanMatcher2D.cs`
+
+**Changes needed:**
+- Line 125: Implement TSDF scoring
+```csharp
+case GridType.TSDF:
+    if (grid is TSDF2D tsdfGrid)
+    {
+        foreach (var point in discreteScan)
+        {
+            var tsd = tsdfGrid.GetTSD(proposedXYIndex);
+            // Score based on distance from zero-crossing (surface)
+            // Cells with TSD near 0 are likely to be on surface
+            candidateScore += -Math.Abs(tsd); // Closer to 0 = better
+        }
+        candidateScore /= discreteScan.Count;
+    }
+    break;
+```
+
+**Note:** TSDF scoring có thể đơn giản hơn ProbabilityGrid vì TSD gần 0 = surface.
+
+---
+
+**4.3.2 CeresScanMatcher2D**
+**File:** `Mapping/Internal/2D/ScanMatching/CeresScanMatcher2D.cs`
+
+**Changes needed:**
+- Line 112-114: Replace TODO với TSDF cost function
+```csharp
+case GridType.TSDF:
+    if (grid is TSDF2D tsdfGrid)
+    {
+        var tsdfMatchCost = TSDFMatchCostFunction2D.CreateAutoDiffCostFunction(
+            _options.OccupiedSpaceWeight / Math.Sqrt(pointCloud.Count),
+            pointCloud,
+            tsdfGrid
+        );
+        problem.AddResidualBlock(tsdfMatchCost, null, [poseParams]);
+    }
+    break;
+```
+
+---
+
+### Phase 5: Integration
+
+#### 5.1 Update RangeDataInserterOptionsProto
+**File:** `Proto/Mapping/RangeDataInserterOptionsProto.cs`
+
+**Changes needed:**
+- Uncomment and add TSDF options:
+```csharp
+[JsonPropertyName("tsdf_range_data_inserter_options_2d")]
+[JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
+public TSDFRangeDataInserterOptions2D? TsdfRangeDataInserterOptions2D { get; set; }
+```
+
+- Update constructor to accept TSDF options
+
+---
+
+#### 5.2 Update ActiveSubmaps2D
+**File:** `Mapping/2D/ActiveSubmaps2D.cs`
+
+**Changes needed:**
+- Line 131: Replace `NotImplementedException` với TSDF2D creation
+```csharp
+GridOptions2D.GridType.Tsdf => new TSDF2D(
+    mapLimits,
+    _options.GridOptions2D.TsdfOptions?.TruncationDistance ?? 0.3f, // Default
+    _options.GridOptions2D.TsdfOptions?.MaxWeight ?? 10.0f, // Default
+    _conversionTables
+),
+```
+
+**Note:** Cần add `TsdfOptions` vào `GridOptions2D` proto nếu chưa có.
+
+---
+
+#### 5.3 Update RangeDataInserterFactory
+**File:** (tìm file tạo RangeDataInserter, có thể trong `Mapping/2D/` hoặc `Mapping/Internal/2D/`)
+
+**Changes needed:**
+- Add TSDF inserter creation:
+```csharp
+case RangeDataInserterOptions.RangeDataInserterType.TsdfInserter2D:
+    if (options.TsdfRangeDataInserterOptions2D.HasValue)
+    {
+        return new TSDFRangeDataInserter2D(options.TsdfRangeDataInserterOptions2D.Value);
+    }
+    throw new ArgumentException("TSDFRangeDataInserterOptions2D is required for TSDF inserter");
+```
+
+---
+
+## 🔗 Dependencies & Order
+
+### Implementation Order:
+1. ✅ **Phase 1**: Core Utilities
+   - TSDValueConverter
+   - NormalEstimation2D
+   - NormalEstimationOptions2DProto (nếu chưa có)
+
+2. ✅ **Phase 2**: TSDF2D Grid
+   - TSDF2D class
+   - Update Grid2DProto
+
+3. ✅ **Phase 3**: Range Data Inserter
+   - TSDFRangeDataInserterOptions2DProto
+   - TSDFRangeDataInserter2D
+
+4. ✅ **Phase 4**: Scan Matching
+   - InterpolatedTSDF2D
+   - TSDFMatchCostFunction2D
+   - Update RealTimeCorrelativeScanMatcher2D
+   - Update CeresScanMatcher2D
+
+5. ✅ **Phase 5**: Integration
+   - Update RangeDataInserterOptionsProto
+   - Update ActiveSubmaps2D
+   - Update RangeDataInserterFactory
+
+---
+
+## 🧪 Testing Plan
+
+### Unit Tests: ✅ COMPLETED
+1. ✅ **TSDValueConverterTests**
+   - ✅ Test TSD/Weight conversion (toValue, fromValue)
+   - ✅ Test bounds (min/max TSD/Weight)
+   - ✅ Test unknown values
+   - ✅ Test update marker
+
+2. ✅ **TSDF2DTests**
+   - ✅ Test SetCell/GetTSD/GetWeight
+   - ✅ Test GetTSDAndWeight
+   - ✅ Test CellIsUpdated
+   - ✅ Test GrowLimits
+   - ✅ Test ComputeCroppedGrid
+   - ✅ Test ToProto/FromProto
+   - ✅ Test out-of-bounds handling
+   - ✅ Test multiple updates with weighted average
+
+3. ✅ **TSDFRangeDataInserter2DTests**
+   - ✅ Test Insert with simple range data
+   - ✅ Test UpdateFreeSpace option
+   - ✅ Test ProjectSdfDistanceToScanNormal option
+   - ✅ Test weight calculation (range, angle, distance)
+   - ✅ Test empty range data handling
+   - ✅ Test wrong grid type error handling
+
+4. ✅ **NormalEstimation2DTests**
+   - ✅ Test normal estimation với known geometry (horizontal/vertical lines, rectangles)
+   - ✅ Test với different sample radii
+   - ✅ Test empty point clouds
+   - ✅ Test single point handling
+
+5. ✅ **InterpolatedTSDF2DTests**
+   - ✅ Test bilinear interpolation
+   - ✅ Test unknown cell handling
+   - ✅ Test GetWeight interpolation
+   - ✅ Test partially unknown cells
+
+6. ⏳ **TSDFMatchCostFunction2DTests**
+   - ⏳ Test cost function evaluation (có thể thêm sau nếu cần)
+   - ⏳ Test with Ceres solver (integration test, có thể thêm sau nếu cần)
+
+### Integration Tests: ⏳ Optional (có thể thêm sau nếu cần)
+1. ⏳ **Full TSDF Pipeline**
+   - Create TSDF2D submap
+   - Insert range data
+   - Perform scan matching (both correlative and Ceres)
+   - Verify pose estimation accuracy
+
+2. ⏳ **TSDF vs ProbabilityGrid Comparison**
+   - Compare mapping quality
+   - Compare scan matching accuracy
+
+**Note:** Core functionality đã được test qua unit tests. Integration tests có thể được thêm sau khi cần validate với real-world data.
+
+---
+
+## 📚 Reference Files
+
+### C++ Implementation:
+- `refs/cartographer/cartographer/mapping/internal/2d/tsd_value_converter.h/cc`
+- `refs/cartographer/cartographer/mapping/internal/2d/tsdf_2d.h/cc`
+- `refs/cartographer/cartographer/mapping/internal/2d/tsdf_range_data_inserter_2d.h/cc`
+- `refs/cartographer/cartographer/mapping/internal/2d/normal_estimation_2d.h/cc`
+- `refs/cartographer/cartographer/mapping/internal/2d/scan_matching/interpolated_tsdf_2d.h`
+- `refs/cartographer/cartographer/mapping/internal/2d/scan_matching/tsdf_match_cost_function_2d.h/cc`
+
+### C++ Tests:
+- `refs/cartographer/cartographer/mapping/internal/2d/tsdf_2d_test.cc`
+- `refs/cartographer/cartographer/mapping/internal/2d/tsdf_range_data_inserter_2d_test.cc`
+- `refs/cartographer/cartographer/mapping/internal/2d/scan_matching/interpolated_tsdf_2d_test.cc`
+- `refs/cartographer/cartographer/mapping/internal/2d/scan_matching/tsdf_match_cost_function_2d_test.cc`
+
+### Proto Files:
+- `refs/cartographer/cartographer/mapping/proto/tsdf_2d.proto`
+- `refs/cartographer/cartographer/mapping/proto/tsdf_range_data_inserter_options_2d.proto`
+- `refs/cartographer/cartographer/mapping/proto/normal_estimation_options_2d.proto`
+
+---
+
+## ⚠️ Notes & Considerations
+
+1. **Performance:**
+   - TSDF computation phức tạp hơn ProbabilityGrid (normal estimation, weighted integration)
+   - Consider caching normal estimates nếu cần
+   - Weight calculation có thể tốn kém (Gaussian kernels)
+
+2. **Memory:**
+   - TSDF2D cần thêm `weight_cells` array (same size as correspondence_cost_cells)
+   - Memory usage ~2x so với ProbabilityGrid
+
+3. **Accuracy:**
+   - TSDF thường cho accuracy cao hơn, đặc biệt với subpixel features
+   - Normal estimation quality ảnh hưởng lớn đến SDF accuracy
+
+4. **Configuration:**
+   - `truncation_distance`: Thường 0.1-0.5m
+   - `maximum_weight`: Thường 10-50
+   - `update_weight_range_exponent`: Thường 0-2
+   - Kernel bandwidths: Cần tune cho từng sensor
+
+5. **Compatibility:**
+   - Ensure TSDF grids có thể serialize/deserialize correctly
+   - Backward compatibility với ProbabilityGrid configs
+
+---
+
+## ✅ Completion Checklist
+
+- [x] Phase 1: Core Utilities ✅ COMPLETED
+  - [x] TSDValueConverter
+  - [x] NormalEstimation2D
+  - [x] NormalEstimationOptions2DProto
+  
+- [x] Phase 2: TSDF2D Grid ✅ COMPLETED
+  - [x] TSDF2D class
+  - [x] Update Grid2DProto (TSDF2DProto)
+  
+- [x] Phase 3: Range Data Inserter ✅ COMPLETED
+  - [x] TSDFRangeDataInserterOptions2DProto
+  - [x] TSDFRangeDataInserter2D
+  - [x] RangeDataSorter helper
+  - [x] RayToPixelMask utility
+  
+- [x] Phase 4: Scan Matching ✅ COMPLETED
+  - [x] InterpolatedTSDF2D
+  - [x] TSDFMatchCostFunction2D
+  - [x] Update RealTimeCorrelativeScanMatcher2D
+  - [x] Update CeresScanMatcher2D
+  
+- [x] Phase 5: Integration ✅ COMPLETED
+  - [x] Update RangeDataInserterOptionsProto
+  - [x] Update ActiveSubmaps2D (CreateGrid và CreateRangeDataInserter)
+  - [x] Update GridOptions2DProto (TSDFOptions2D)
+  
+- [x] Testing ✅ COMPLETED
+  - [x] Unit tests cho tất cả components
+    - [x] TSDValueConverterTests
+    - [x] TSDF2DTests
+    - [x] NormalEstimation2DTests
+    - [x] TSDFRangeDataInserter2DTests
+    - [x] InterpolatedTSDF2DTests
+  - [ ] Integration tests (có thể thêm sau nếu cần)
+  - [ ] Performance benchmarks (có thể thêm sau nếu cần)
+
+---
+
+**Last Updated:** 2024-12-19
+**Status:** ✅ **IMPLEMENTATION COMPLETED** - All phases implemented with comprehensive unit tests
+