diff --git a/src/Aardvark.Algodat.Tests/Program.cs b/src/Aardvark.Algodat.Tests/Program.cs
index d6516326..c17ee39b 100644
--- a/src/Aardvark.Algodat.Tests/Program.cs
+++ b/src/Aardvark.Algodat.Tests/Program.cs
@@ -34,16 +34,22 @@ namespace Aardvark.Geometry.Tests
 {
     public class Program
     {
-        internal static Task CreateStore(string filename, string storeDir, double minDist)
+        #region CreateStore
+
+        internal static Task<string> CreateStore(string filename, string storeDir, double minDist)
             => CreateStore(filename, new DirectoryInfo(storeDir), minDist);
 
-        internal static Task CreateStore(string filename, DirectoryInfo storeDir, double minDist)
+        internal static Task<string> CreateStore(IEnumerable<Chunk> chunks, string storeDir, double minDist, int? splitLimit = null)
+            => CreateStore(chunks, new DirectoryInfo(storeDir), minDist, splitLimit);
+
+        internal static Task<string> CreateStore(string filename, DirectoryInfo storeDir, double minDist)
         {
             if (!storeDir.Exists) storeDir.Create();
 
             var key = Path.GetFileName(filename);
 
             using var store = new SimpleDiskStore(Path.Combine(storeDir.FullName, "data.uds")).ToPointCloudStore();
+
             var config = ImportConfig.Default
                 .WithStorage(store)
                 .WithKey(key)
@@ -53,6 +59,7 @@ internal static Task CreateStore(string filename, DirectoryInfo storeDir, double
                 .WithNormalizePointDensityGlobal(true)
                 //.WithMaxChunkPointCount(32 * 1024 * 1024)
                 //.WithOctreeSplitLimit(8192*4)
+                //.WithEnabledPartIndices(false)
                 ;
 
             Report.BeginTimed($"importing {filename}");
@@ -61,9 +68,42 @@ internal static Task CreateStore(string filename, DirectoryInfo storeDir, double
 
             File.WriteAllText(Path.Combine(storeDir.FullName, "key.txt"), key);
 
-            return Task.CompletedTask;
+            return Task.FromResult(key);
+        }
+
+        internal static Task<string> CreateStore(IEnumerable<Chunk> chunks, DirectoryInfo storeDir, double minDist, int? splitLimit = null)
+        {
+            if (!storeDir.Exists) storeDir.Create();
+
+            var filename = storeDir.FullName;
+            var key = Path.GetFileName(filename);
+
+            using var store = new SimpleDiskStore(Path.Combine(storeDir.FullName, "data.uds")).ToPointCloudStore();
+
+            var config = ImportConfig.Default
+                .WithStorage(store)
+                .WithKey(key)
+                .WithVerbose(true)
+                .WithMaxDegreeOfParallelism(0)
+                .WithMinDist(minDist)
+                .WithNormalizePointDensityGlobal(true)
+                //.WithMaxChunkPointCount(32 * 1024 * 1024)
+                //.WithEnabledPartIndices(false)
+                ;
+
+            if (splitLimit.HasValue) config = config.WithOctreeSplitLimit(splitLimit.Value);
+
+            Report.BeginTimed($"importing {filename}");
+            var pcl = PointCloud.Import(chunks, config);
+            Report.EndTimed();
+
+            File.WriteAllText(Path.Combine(storeDir.FullName, "key.txt"), key);
+
+            return Task.FromResult(key);
         }
 
+        #endregion
+
         internal static void PerfTestJuly2019()
         {
             var filename = @"T:\Vgm\Data\2017-10-20_09-44-27_1mm_shade_norm_5pp - Cloud.pts";
@@ -2689,22 +2729,51 @@ static Task Parts_Test_20231006()
 
             return Task.CompletedTask;
         }
+        static async Task Parts_Test_20231006_Merge()
+        {
+            V3d[] randomPoints(int n, Box3d bb)
+            {
+                var size = bb.Size;
+                var ps = new V3d[n];
+                for (var i = 0; i < n; i++)
+                {
+                    ps[i] = bb.Min + new V3d(Random.Shared.NextDouble(), Random.Shared.NextDouble(), Random.Shared.NextDouble()) * size;
+                }
+
+                return ps;
+            }
+
+            var c0 = new Chunk(positions: randomPoints(10, Box3d.Unit          ), null, null, null, null, partIndices: 0, null, null);
+            var c1 = new Chunk(positions: randomPoints(10, Box3d.Unit + V3d.IOO), null, null, null, null, partIndices: 1, null, null);
+
+            var storeDir = @"W:\Datasets\Vgm\Stores\test_partindex";
+            var key = await CreateStore(
+                new [] { c0, c1 },
+                storeDir,
+                minDist: 0.01,
+                splitLimit: 10
+                );
+
+            using var store = new SimpleDiskStore(Path.Combine(storeDir, "data.uds")).ToPointCloudStore();
+            var ps = store.GetPointSet(key);
+            var root = ps.Root.Value;
+        }
 
         public static async Task Main(string[] _)
         {
-            await Task.Delay(0); // avoid warnings if main contains no await
+            //await Task.Delay(0); // avoid warnings if main contains no await
 
+            await CreateStore(
+                @"W:\Datasets\Vgm\Data\structured_pointclouds\lowergetikum 20230321.e57",
+                @"W:\Datasets\Vgm\Stores\lowergetikum 20230321.e57_0.01",
+                minDist: 0.01
+                );
 
+            //await Parts_Test_20231006_Merge();
 
             //await Parts_Test_20231006();
 
-            Test_Import_Regression();
-
-            //await CreateStore(
-            //    @"T:\Kindergarten.pts",
-            //    @"W:\Aardworx\pointshare2\testdata\2023-08-01_kindergarten.store",
-            //    minDist: 0.0
-            //    );
+            //Test_Import_Regression();
 
             //await Ranges_Test_20230802();
 
diff --git a/src/Aardvark.Data.E57/Aardvark.Data.E57.csproj b/src/Aardvark.Data.E57/Aardvark.Data.E57.csproj
index b8396a73..c06f399c 100644
--- a/src/Aardvark.Data.E57/Aardvark.Data.E57.csproj
+++ b/src/Aardvark.Data.E57/Aardvark.Data.E57.csproj
@@ -3,6 +3,7 @@
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
     <LangVersion>10</LangVersion>
+    <ErrorOnDuplicatePublishOutputFiles>false</ErrorOnDuplicatePublishOutputFiles>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">
     <OutputPath>..\..\bin\Debug</OutputPath>
diff --git a/src/Aardvark.Data.E57/ImportE57.cs b/src/Aardvark.Data.E57/ImportE57.cs
index 2afd4035..ef44ba82 100644
--- a/src/Aardvark.Data.E57/ImportE57.cs
+++ b/src/Aardvark.Data.E57/ImportE57.cs
@@ -195,7 +195,7 @@ public static IEnumerable<Chunk> Chunks(this Stream stream, long streamLengthInB
                 var yieldedRecordCount = 0L;
 
                 var partIndex = config.PartIndexOffset;
-                foreach (var data3d in header.E57Root.Data3D)
+                foreach (var data3d in header.E57Root.Data3D.Take(2))
                 {
                     foreach (var (Positions, Properties) in data3d.StreamPointsFull(config.MaxChunkPointCount, config.Verbose, exclude))
                     {
diff --git a/src/Aardvark.Geometry.PointSet/Aardvark.Geometry.PointSet.csproj b/src/Aardvark.Geometry.PointSet/Aardvark.Geometry.PointSet.csproj
index 1d2b8143..84a33b8d 100644
--- a/src/Aardvark.Geometry.PointSet/Aardvark.Geometry.PointSet.csproj
+++ b/src/Aardvark.Geometry.PointSet/Aardvark.Geometry.PointSet.csproj
@@ -8,6 +8,7 @@
     <DocumentationFile>..\..\bin\Release\netstandard2.0\Aardvark.Geometry.PointSet.xml</DocumentationFile>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>    
     <RootNamespace>Aardvark.Geometry.Points</RootNamespace>
+    <ErrorOnDuplicatePublishOutputFiles>false</ErrorOnDuplicatePublishOutputFiles>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">
     <OutputPath>..\..\bin\Debug</OutputPath>
diff --git a/src/Aardvark.Geometry.PointSet/Octrees/IPointCloudNodeExtensions.cs b/src/Aardvark.Geometry.PointSet/Octrees/IPointCloudNodeExtensions.cs
index 4311ccf9..e2c572c7 100644
--- a/src/Aardvark.Geometry.PointSet/Octrees/IPointCloudNodeExtensions.cs
+++ b/src/Aardvark.Geometry.PointSet/Octrees/IPointCloudNodeExtensions.cs
@@ -839,6 +839,7 @@ IEnumerable<Chunk> QueryRec(IPointCloudNode n)
         public static void CheckDerivedAttributes(this IPointCloudNode self)
         {
             var isTmpNode = self.Has(PointSetNode.TemporaryImportNode);
+
             if (self.HasPositions)
             {
                 if (!self.HasKdTree && !isTmpNode) throw new InvalidOperationException(
@@ -863,12 +864,34 @@ public static void CheckDerivedAttributes(this IPointCloudNode self)
                 //    "Missing PointDistanceStandardDeviation. Invariant 4a03c3f5-a625-4124-91f6-6f79fd1b5d0e."
                 //    );
             }
+
             if (!self.HasMaxTreeDepth) throw new InvalidOperationException(
                 "Missing MaxTreeDepth. Invariant c7c3c337-5404-4773-aae3-01d213e575b0."
                 );
             if (!self.HasMinTreeDepth) throw new InvalidOperationException(
                 "Missing MinTreeDepth. Invariant 2df9fb7b-684a-4103-8f14-07785607d2f4."
                 );
+
+            if (self.HasPartIndexRange && !self.HasPartIndices) throw new InvalidOperationException(
+                    "Missing part indices. Invariant fc4ff983-151f-4956-b882-54d649245049."
+                    );
+
+            if (self.HasPartIndices)
+            {
+                if (!self.HasPartIndexRange) throw new InvalidOperationException(
+                    "Missing PartIndexRange. Invariant 90571267-b593-4458-83d6-5448dd9c5257."
+                    );
+
+                if (self.Has(Durable.Octree.PerPointPartIndex1b)) throw new InvalidOperationException(
+                    "PerPointPartIndex1b should be PerPointPartIndex1bReference. Invariant 85879fd8-7ee8-45a0-b221-67f826bc42df."
+                    );
+                if (self.Has(Durable.Octree.PerPointPartIndex1s)) throw new InvalidOperationException(
+                    "PerPointPartIndex1s should be PerPointPartIndex1sReference. Invariant 598f615b-289a-4bfe-b5cf-b61e4bd380d5."
+                    );
+                if (self.Has(Durable.Octree.PerPointPartIndex1i)) throw new InvalidOperationException(
+                    "PerPointPartIndex1i should be PerPointPartIndex1iReference. Invariant d5391b75-bbc1-4c83-b963-50fd0f409931."
+                    );
+            }
         }
 
         /// <summary>
diff --git a/src/Aardvark.Geometry.PointSet/Octrees/InMemoryPointSet.cs b/src/Aardvark.Geometry.PointSet/Octrees/InMemoryPointSet.cs
index 8b6cafae..5b91ff02 100644
--- a/src/Aardvark.Geometry.PointSet/Octrees/InMemoryPointSet.cs
+++ b/src/Aardvark.Geometry.PointSet/Octrees/InMemoryPointSet.cs
@@ -25,18 +25,6 @@ namespace Aardvark.Geometry.Points
 {
     public class InMemoryPointSet
     {
-        /// <summary>
-        /// The following attribute arrays will be stored stand-alone and referenced via id.
-        /// </summary>
-        public static Dictionary<Def, Def> StoreAsReference { get; } = new Dictionary<Def, Def>()
-            {
-                { Octree.PositionsLocal3f,  Octree.PositionsLocal3fReference    },
-                { Octree.Colors4b,          Octree.Colors4bReference            },
-                { Octree.Normals3f,         Octree.Normals3fReference           },
-                { Octree.Intensities1i,     Octree.Intensities1iReference       },
-                { Octree.Classifications1b, Octree.Classifications1bReference   }
-            };
-
         private readonly ImmutableDictionary<Def, object> m_data;
         private readonly int m_splitLimit;
         private readonly Node m_root;
@@ -166,145 +154,137 @@ public Node(InMemoryPointSet octree, Cell cell)
                 _centerX = c.X; _centerY = c.Y; _centerZ = c.Z;
             }
 
+
+            /// <summary>
+            /// The following arrays will be stored as separate entries in the store and referenced via id.
+            /// </summary>
+            private static readonly Dictionary<Def, Def> StoreAsReference = new()
+            {
+                { Octree.PositionsLocal3f   , Octree.PositionsLocal3fReference    },
+                { Octree.Colors4b           , Octree.Colors4bReference            },
+                { Octree.Normals3f          , Octree.Normals3fReference           },
+                { Octree.Intensities1i      , Octree.Intensities1iReference       },
+                { Octree.Classifications1b  , Octree.Classifications1bReference   },
+                { Octree.PerPointPartIndex1b, Octree.PerPointPartIndex1bReference },
+                { Octree.PerPointPartIndex1s, Octree.PerPointPartIndex1sReference },
+                { Octree.PerPointPartIndex1i, Octree.PerPointPartIndex1iReference },
+            };
+
+
             internal PointSetNode ToPointSetNode(Storage storage, bool isTemporaryImportNode)
             {
-                var center = new V3d(_centerX, _centerY, _centerZ);
-                V3f[]? localPositions = null;
+                // final result data (which we will use to create a PointSetNode)
+                var resultData = ImmutableDictionary<Def, object>.Empty
+                    .Add(Octree.NodeId, Guid.NewGuid())
+                    .Add(Octree.Cell, _cell)
+                    ;
+
+                if (isTemporaryImportNode) resultData = resultData.Add(PointSetNode.TemporaryImportNode, 0);
+
+                // keep track whether we really convert all existing data entries to a PointSetNode
+                // (so we can fail if something is left over at the end, something we did not expect or handle correctly)
+                var notHandled = new HashSet<Def>(_octree.m_data.Keys);
 
-                var attributes = ImmutableDictionary<Def, object>.Empty;
+                var center = new V3d(_centerX, _centerY, _centerZ);
 
-                if (_ia != null)
+                if (_subnodes == null)
                 {
-                    var count = _ia.Count;
+                    // leaf node ...
 
-                    // compute positions attribute (relative to center)
-                    var allPs = _octree.m_ps;
-                    localPositions = new V3f[count];
-                    for (var i = 0; i < count; i++) localPositions[i] = (V3f)(allPs[_ia[i]] - center); // relative to center
-                    attributes = attributes.Add(Octree.PositionsLocal3f, localPositions);
+                    #region positions
 
-                    // create all other attributes ...
-                    foreach (var kv in _octree.m_data)
+                    // transform global float64 positions to local float32 positions (relative to cell center) to save space
+                    var psGlobal = _octree.m_ps;
+                    V3f[] psLocal;
+                    if (_ia != null)
                     {
-                        if (kv.Key == Octree.PositionsGlobal3d ||
-                            kv.Key == Octree.PerCellPartIndex1i ||
-                            kv.Key == Octree.PerCellPartIndex1ui ||
-                            kv.Key == Octree.PerPointPartIndex1b ||
-                            kv.Key == Octree.PerPointPartIndex1s ||
-                            kv.Key == Octree.PerPointPartIndex1i ||
-                            kv.Key == Octree.PartIndexRange
-                            )
-                            continue;
-                        var subset = kv.Value.Subset(_ia);
-                        attributes = attributes.Add(kv.Key, subset);
+                        psLocal = new V3f[_ia.Count];
+                        for (var i = 0; i < _ia.Count; i++) psLocal[i] = (V3f)(psGlobal[_ia[i]] - center); // relative to center
+                    }
+                    else
+                    {
+                        psLocal = new V3f[psGlobal.Count];
+                        for (var i = 0; i < psGlobal.Count; i++) psLocal[i] = (V3f)(psGlobal[i] - center); // relative to center
                     }
-                }
 
-                // subcells ...
-                var subcells = _subnodes?.Map(x => x?.ToPointSetNode(storage, isTemporaryImportNode));
-                var subcellIds = subcells?.Map(x => x?.Id);
-                var isLeaf = _subnodes == null;
+                    var bbExactLocal = new Box3f(psLocal);
 
-#if DEBUG
-                if (_subnodes != null)
-                {
-                    if (localPositions != null)
-                        throw new InvalidOperationException("Invariant d98ea55b-760c-4564-8076-ce9cf7d293a0.");
+                    resultData = resultData
+                        .Add(Octree.PositionsLocal3f, psLocal)
+                        .Add(Octree.PointCountCell, psLocal.Length)
+                        .Add(Octree.PointCountTreeLeafs, (long)psLocal.Length)
+                        .Add(Octree.BoundingBoxExactLocal, bbExactLocal)
+                        .Add(Octree.BoundingBoxExactGlobal, (Box3d)bbExactLocal + center)
+                        ;
 
-                    for (var i = 0; i < 8; i++)
+                    #endregion
+
+                    #region per-point attribute arrays
+
+                    var handledPerPointAttributeArrays = new List<Def>();
+                    foreach (var k in notHandled)
                     {
-                        var sn = _subnodes[i]; if (sn == null) continue;
-                        if (sn._cell.Exponent != this._cell.Exponent - 1)
+                        if (StoreAsReference.TryGetValue(k, out var refdef))
                         {
-                            throw new InvalidOperationException("Invariant 2c33afb4-683b-4f71-9e1f-36ec4a79fba1.");
-                        }
-                    }
-                }
-#endif
-                var pointCountTreeLeafs = subcells != null
-                    ? subcells.Sum(n => n != null ? n.PointCountTree : 0)
-                    : localPositions!.Length
-                    ;
+                            var xs = (Array)_octree.m_data[k];
+                            if (_ia != null) xs = xs.Subset(_ia);
 
-                var data = ImmutableDictionary<Def, object>.Empty
-                    .Add(Octree.NodeId, Guid.NewGuid())
-                    .Add(Octree.Cell, _cell)
-                    .Add(Octree.PointCountTreeLeafs, pointCountTreeLeafs)
-                    ;
+                            // store separately and reference by id ...
+                            var id = Guid.NewGuid();
+                            storage.Add(id, xs);
+                            resultData = resultData.Add(refdef, id);
 
-                if (isTemporaryImportNode)
-                {
-                    data = data.Add(PointSetNode.TemporaryImportNode, 0);
-                }
+                            handledPerPointAttributeArrays.Add(k);
+                        }
+                    }
+                    foreach (var k in handledPerPointAttributeArrays) notHandled.Remove(k);
 
-                if (attributes.TryGetValue(Octree.PositionsLocal3f, out var psObj))
-                {
-                    var ps = (V3f[])psObj;
-                    var bbExactLocal = new Box3f(ps);
+                    #endregion
 
-                    data = data
-                        .Add(Octree.PointCountCell, ps.Length)
-                        .Add(Octree.BoundingBoxExactLocal, bbExactLocal)
-                        .Add(Octree.BoundingBoxExactGlobal, (Box3d)bbExactLocal + center)
-                        ;
-                }
-                else
-                {
-                    data = data
-                        .Add(Octree.PointCountCell, 0)
-                        ;
-                }
+                    #region other well-known entries
 
-                // part indices ...
-                {
                     void copy(Def def)
                     {
                         if (_octree.m_data.TryGetValue(def, out var o))
                         {
-                            data = data.Add(def, o);
+                            resultData = resultData.Add(def, o);
+                            notHandled.Remove(def);
                         }
                     }
 
+                    copy(Octree.PartIndexRange);
                     copy(Octree.PerCellPartIndex1i);
                     copy(Octree.PerCellPartIndex1ui);
-                    copy(Octree.PartIndexRange);
 
-                    if (
-                        _octree.m_data.TryGetValue(Octree.PerPointPartIndex1b, out object? qs) ||
-                        _octree.m_data.TryGetValue(Octree.PerPointPartIndex1s, out qs) ||
-                        _octree.m_data.TryGetValue(Octree.PerPointPartIndex1i, out qs)
-                        )
-                    {
-                        qs = _ia != null ? PartIndexUtils.Subset(qs, _ia) : qs;
-                        if (qs != null) data = data.Add(PartIndexUtils.GetDurableDefForPartIndices(qs), qs);
-                    }
-                }
+                    #endregion
 
-                // save attribute arrays to store ...
-                foreach (var kv in attributes)
-                {
-                    if (StoreAsReference.TryGetValue(kv.Key, out var refdef))
-                    {
-                        // store separately and reference by id ...
-                        var id = Guid.NewGuid();
-                        storage.Add(id, (Array)kv.Value);
-                        data = data.Add(refdef, id);
-                    }
-                    else
-                    {
-                        // store inline (inside node) ...
-                        data = data.Add(kv.Key, kv.Value);
-                    }
-                }
+                    if (notHandled.Count > 0) throw new Exception(
+                        $"Unhandled entries {string.Join(", ", notHandled.Select(x => x.ToString()))}. " +
+                        $"Invariant 42656f92-f5ac-43ca-a1b7-c7ec95fe9cb3."
+                        );
 
-                if (isLeaf) // leaf
-                {
-                    var result = new PointSetNode(data, storage, writeToStore: true);
-                    if (storage.GetPointCloudNode(result.Id) == null) throw new InvalidOperationException("Invariant d1022027-2dbf-4b11-9b40-4829436f5789.");
+                    var result = new PointSetNode(resultData, storage, writeToStore: true);
+                    if (storage.GetPointCloudNode(result.Id) == null) throw new InvalidOperationException("Invariant 9e863bc5-e9f4-4d39-bd53-3d81e12af6b1.");
                     return result;
                 }
                 else
                 {
+                    // inner node ...
+
+                    var subcells = _subnodes?.Map(x => x?.ToPointSetNode(storage, isTemporaryImportNode));
+                    var subcellIds = subcells?.Map(x => x?.Id);
+
+                    var pointCountTreeLeafs =  subcells.Sum(n => n != null ? n.PointCountTree : 0);
+                    var bbExactGlobal = new Box3d(subcells.Where(x => x != null).Select(x => x!.BoundingBoxExactGlobal));
+                    var bbExactLocal = (Box3f)(bbExactGlobal - center);
+
+                    resultData = resultData
+                        .Add(Octree.PointCountTreeLeafs, pointCountTreeLeafs)
+                        .Add(Octree.BoundingBoxExactLocal, bbExactLocal)
+                        .Add(Octree.BoundingBoxExactGlobal, bbExactGlobal)
+                        .Add(Octree.SubnodesGuids, subcellIds.Map(x => x ?? Guid.Empty))
+                        ;
+
                     for (var i = 0; i < 8; i++)
                     {
                         var x = subcellIds![i];
@@ -314,15 +294,76 @@ void copy(Def def)
                             if (storage.GetPointCloudNode(id) == null) throw new InvalidOperationException("Invariant 01830b8b-3c0e-4a8b-a1bd-bfd1b1be1844.");
                         }
                     }
-                    var bbExactGlobal = new Box3d(subcells.Where(x => x != null).Select(x => x!.BoundingBoxExactGlobal));
-                    data = data
-                        .Add(Octree.BoundingBoxExactGlobal, bbExactGlobal)
-                        .Add(Octree.SubnodesGuids, subcellIds.Map(x => x ?? Guid.Empty))
-                        ;
-                    var result = new PointSetNode(data, storage, writeToStore: true);
+
+                    var result = new PointSetNode(resultData, storage, writeToStore: true);
                     if (storage.GetPointCloudNode(result.Id) == null) throw new InvalidOperationException("Invariant 7b09eccb-b6a0-4b99-be7a-eeff53b6a98b.");
                     return result;
                 }
+
+                // stuff
+                //var attributes = ImmutableDictionary<Def, object>.Empty;
+
+                /*
+                 * EXPLAINER:
+                 * 
+                 * If  _ia  exists, then this means that a subset of all per-point attribute arrays (positions, colors, ...) has to be taken (according to the indices stored in _ia)
+                 * otherwise these arrays can be used as they are
+                 * 
+                 */
+
+                
+
+                //if (_ia != null)
+                //{
+                //    var count = _ia.Count;
+
+                //    // create all other attributes ...
+                //    foreach (var kv in _octree.m_data)
+                //    {
+                //        if (kv.Key == Octree.PositionsGlobal3d ||
+                //            kv.Key == Octree.PerCellPartIndex1i ||
+                //            kv.Key == Octree.PerCellPartIndex1ui ||
+                //            kv.Key == Octree.PerPointPartIndex1b ||
+                //            kv.Key == Octree.PerPointPartIndex1s ||
+                //            kv.Key == Octree.PerPointPartIndex1i ||
+                //            kv.Key == Octree.PartIndexRange
+                //            )
+                //            continue;
+                //        var subset = kv.Value.Subset(_ia);
+                //        attributes = attributes.Add(kv.Key, subset);
+                //    }
+                //}
+                //else
+                //{
+
+                //}
+
+
+                //// part indices ...
+                //{
+                //    void copy(Def def)
+                //    {
+                //        if (_octree.m_data.TryGetValue(def, out var o))
+                //        {
+                //            data = data.Add(def, o);
+                //        }
+                //    }
+
+                //    copy(Octree.PerCellPartIndex1i);
+                //    copy(Octree.PerCellPartIndex1ui);
+                //    copy(Octree.PartIndexRange);
+
+                //    //if (
+                //    //    _octree.m_data.TryGetValue(Octree.PerPointPartIndex1b, out object? qs) ||
+                //    //    _octree.m_data.TryGetValue(Octree.PerPointPartIndex1s, out qs) ||
+                //    //    _octree.m_data.TryGetValue(Octree.PerPointPartIndex1i, out qs)
+                //    //    )
+                //    //{
+                //    //    qs = _ia != null ? PartIndexUtils.Subset(qs, _ia) : qs;
+                //    //    if (qs != null) data = data.Add(PartIndexUtils.GetDurableDefForPartIndices(qs), qs);
+                //    //}
+                //}
+
             }
             
             public Node Insert(int index)
diff --git a/src/Aardvark.Geometry.PointSet/Octrees/Merge.cs b/src/Aardvark.Geometry.PointSet/Octrees/Merge.cs
index 168747c3..d3b1fc90 100644
--- a/src/Aardvark.Geometry.PointSet/Octrees/Merge.cs
+++ b/src/Aardvark.Geometry.PointSet/Octrees/Merge.cs
@@ -378,11 +378,27 @@ public static (IPointCloudNode, bool) Merge(this IPointCloudNode a, IPointCloudN
                 if (qs != null) 
                 {
                     if (qsRange == null) throw new Exception("Invariant 7c01f554-d833-42cc-ab1d-9dbaa61bef45.");
-                    var def = PartIndexUtils.GetDurableDefForPartIndices(qs);
-                    data = data
-                        .Add(def, qs)
-                        .Add(Durable.Octree.PartIndexRange, qsRange)
-                        ;
+                    data = data.Add(Durable.Octree.PartIndexRange, qsRange);
+
+                    if (qs is Array qsArray)
+                    {
+                        // store separately and reference by id ...
+                        var id = Guid.NewGuid();
+                        storage.Add(id, qsArray);
+                        data = qs switch
+                        {
+                            byte[]  => data.Add(Durable.Octree.PerPointPartIndex1bReference, id),
+                            short[] => data.Add(Durable.Octree.PerPointPartIndex1sReference, id),
+                            int[]   => data.Add(Durable.Octree.PerPointPartIndex1iReference, id),
+                            _       => throw new Exception($"Unexpected type {qs.GetType()}. Invariant cc05e74c-8cac-4d32-9972-0ea53e6e0911."),
+                        };
+                    }
+                    else
+                    {
+                        var def = PartIndexUtils.GetDurableDefForPartIndices(qs);
+                        data = data.Add(def, qs);
+                    }
+                    
                 }
 
                 var result = new PointSetNode(data, config.Storage, writeToStore: true);
diff --git a/src/Aardvark.Geometry.PointSet/Octrees/PointSet.cs b/src/Aardvark.Geometry.PointSet/Octrees/PointSet.cs
index 13581cbd..d32ec5a1 100644
--- a/src/Aardvark.Geometry.PointSet/Octrees/PointSet.cs
+++ b/src/Aardvark.Geometry.PointSet/Octrees/PointSet.cs
@@ -16,12 +16,10 @@ You should have received a copy of the GNU Affero General Public License
 using System;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
-using System.Linq;
 using System.Text.Json;
 using System.Text.Json.Nodes;
 using System.Text.Json.Serialization;
 using System.Threading;
-using static Aardvark.Base.MultimethodTest;
 
 namespace Aardvark.Geometry.Points
 {
diff --git a/src/Aardvark.Geometry.PointSet/Octrees/PointSetNode.cs b/src/Aardvark.Geometry.PointSet/Octrees/PointSetNode.cs
index 7facce95..64ecbc17 100644
--- a/src/Aardvark.Geometry.PointSet/Octrees/PointSetNode.cs
+++ b/src/Aardvark.Geometry.PointSet/Octrees/PointSetNode.cs
@@ -116,9 +116,9 @@ public PointSetNode(
                 var bb = new Box3d(PositionsAbsolute);
                 if (!Cell.BoundingBox.Contains(bb)) throw new Exception($"Invariant 71e949d7-21b1-4150-bfe3-337db52c4c7d.");
 
-                // Invariant: cell of bounding box of global positions MUST EQUAL node cell
-                var bbCell = new Cell(bb);
-                if (Cell != bbCell) throw new InvalidOperationException($"Invariant 7564f5b1-1b70-45cf-bfbe-5c955b90d1fe.");
+                //// Invariant: cell of bounding box of global positions MUST EQUAL node cell
+                //var bbCell = new Cell(bb);
+                //if (Cell != bbCell) throw new InvalidOperationException($"Invariant 7564f5b1-1b70-45cf-bfbe-5c955b90d1fe.");
             }
 #endif
 
@@ -153,7 +153,7 @@ public PointSetNode(
 
 #endregion
 
-#region Per-point attributes
+            #region Per-point attributes
 
             var psId = PositionsId;
             var csId = ColorsId;
@@ -186,9 +186,9 @@ Func<string, T> throwWhenNull<T>(Func<string, T?> f) where T : notnull
             if (isId != null) PersistentRefs[Durable.Octree.Intensities1iReference    ] = new PersistentRef<int[] >(isId.Value, throwWhenNull(storage.GetIntArray ), storage.TryGetIntArrayFromCache );
             if (ksId != null) PersistentRefs[Durable.Octree.Classifications1bReference] = new PersistentRef<byte[]>(ksId.Value, throwWhenNull(storage.GetByteArray), storage.TryGetByteArrayFromCache);
 
-#endregion
+            #endregion
 
-#region Durable.Octree.BoundingBoxExactLocal, Durable.Octree.BoundingBoxExactGlobal
+            #region Durable.Octree.BoundingBoxExactLocal, Durable.Octree.BoundingBoxExactGlobal
 
             if (HasPositions && (!HasBoundingBoxExactLocal || !HasBoundingBoxExactGlobal))
             {
@@ -218,18 +218,18 @@ Func<string, T> throwWhenNull<T>(Func<string, T?> f) where T : notnull
                 }
             }
 
-#endregion
+            #endregion
 
-#region Durable.Octree.PointCountCell
+            #region Durable.Octree.PointCountCell
 
             if (!Has(Durable.Octree.PointCountCell))
             {
                 Data = Data.Add(Durable.Octree.PointCountCell, HasPositions ? Positions.Value!.Length : 0);
             }
 
-#endregion
+            #endregion
 
-#region Durable.Octree.PointCountTreeLeafs
+            #region Durable.Octree.PointCountTreeLeafs
 
             if (!Has(Durable.Octree.PointCountTreeLeafs))
             {
@@ -243,9 +243,9 @@ Func<string, T> throwWhenNull<T>(Func<string, T?> f) where T : notnull
                 }
             }
 
-#endregion
+            #endregion
 
-#region Centroid*
+            #region Centroid*
 
             if (HasPositions && (!HasCentroidLocal || !HasCentroidLocalStdDev))
             {
@@ -268,9 +268,10 @@ Func<string, T> throwWhenNull<T>(Func<string, T?> f) where T : notnull
                     }
                 }
             }
-#endregion
 
-#region TreeDepth*
+            #endregion
+
+            #region TreeDepth*
 
             if (!HasMinTreeDepth || !HasMaxTreeDepth)
             {
@@ -316,9 +317,9 @@ Func<string, T> throwWhenNull<T>(Func<string, T?> f) where T : notnull
                 }
             }
 
-#endregion
+            #endregion
 
-#region KdTree
+            #region KdTree
 
             if (HasPositions && !HasKdTree && !IsTemporaryImportNode)
             {
@@ -419,34 +420,6 @@ PointRkdTreeF<V3f[], V3f> LoadKdTreeObsolete(string key)
                     );
             }
 
-            //(bool, PointRkdTreeF<V3f[], V3f>?) TryLoadKdTree(string key)
-            //{
-            //    var (ok, value) = Storage.TryGetPointRkdTreeFData(key);
-            //    if (ok == false) return (false, default);
-            //    var ps = Positions.Value!;
-            //    return (true, new PointRkdTreeF<V3f[], V3f>(
-            //        3, ps.Length, ps,
-            //        (xs, i) => xs[(int)i], (v, i) => (float)v[i],
-            //        (a, b) => Vec.Distance(a, b), (i, a, b) => b - a,
-            //        (a, b, c) => Vec.DistanceToLine(a, b, c), Fun.Lerp, 1e-6f,
-            //        value
-            //        ));
-            //}
-
-            //(bool, PointRkdTreeF<V3f[], V3f>?) TryLoadKdTreeObsolete(string key)
-            //{
-            //    var (ok, value) = Storage.TryGetPointRkdTreeFDataFromD(key);
-            //    if (ok == false) return (false, default);
-            //    var ps = Positions.Value!;
-            //    return (true, new PointRkdTreeF<V3f[], V3f>(
-            //        3, ps.Length, ps,
-            //        (xs, i) => xs[(int)i], (v, i) => (float)v[i],
-            //        (a, b) => Vec.Distance(a, b), (i, a, b) => b - a,
-            //        (a, b, c) => Vec.DistanceToLine(a, b, c), Fun.Lerp, 1e-6f,
-            //        value
-            //        ));
-            //}
-
             bool TryLoadKdTreeOut(string key, [NotNullWhen(true)] out PointRkdTreeF<V3f[], V3f>? result)
             {
                 var (ok, value) = Storage.TryGetPointRkdTreeFData(key);
@@ -922,8 +895,11 @@ public PersistentRef<byte[]>? Classifications
             Data.ContainsKey(Durable.Octree.PerCellPartIndex1i ) ||
             Data.ContainsKey(Durable.Octree.PerCellPartIndex1ui) ||
             Data.ContainsKey(Durable.Octree.PerPointPartIndex1b) ||
+            Data.ContainsKey(Durable.Octree.PerPointPartIndex1bReference) ||
             Data.ContainsKey(Durable.Octree.PerPointPartIndex1s) ||
-            Data.ContainsKey(Durable.Octree.PerPointPartIndex1i)
+            Data.ContainsKey(Durable.Octree.PerPointPartIndex1sReference) ||
+            Data.ContainsKey(Durable.Octree.PerPointPartIndex1i) ||
+            Data.ContainsKey(Durable.Octree.PerPointPartIndex1iReference)
             ;
 
         /// <summary>
@@ -937,12 +913,24 @@ public object? PartIndices
                 if (Data.TryGetValue(Durable.Octree.PerCellPartIndex1i, out var pcpi)) return pcpi;
                 else if (Data.TryGetValue(Durable.Octree.PerCellPartIndex1ui, out var pcpui)) return pcpui;
                 else if (Data.TryGetValue(Durable.Octree.PerPointPartIndex1b, out var pppi1b)) return pppi1b;
+                else if (Data.TryGetValue(Durable.Octree.PerPointPartIndex1bReference, out var key1b)) return Storage.GetByteArray((Guid)key1b);
                 else if (Data.TryGetValue(Durable.Octree.PerPointPartIndex1s, out var pppi1s)) return pppi1s;
+                else if (Data.TryGetValue(Durable.Octree.PerPointPartIndex1sReference, out var key1s)) return Storage.GetInt16Array((Guid)key1s);
                 else if (Data.TryGetValue(Durable.Octree.PerPointPartIndex1i, out var pppi1i)) return pppi1i;
+                else if (Data.TryGetValue(Durable.Octree.PerPointPartIndex1iReference, out var key1i)) return Storage.GetIntArray((Guid)key1i);
                 else return null;
             }
         }
 
+        [JsonIgnore]
+        public Guid? PerPointPartIndex1bId => Data.TryGetValue(Durable.Octree.PerPointPartIndex1bReference, out var id) ? (Guid?)id : null;
+
+        [JsonIgnore]
+        public Guid? PerPointPartIndex1sId => Data.TryGetValue(Durable.Octree.PerPointPartIndex1sReference, out var id) ? (Guid?)id : null;
+
+        [JsonIgnore]
+        public Guid? PerPointPartIndex1iId => Data.TryGetValue(Durable.Octree.PerPointPartIndex1iReference, out var id) ? (Guid?)id : null;
+
         /// <summary>
         /// Get per-point part indices as an int array (regardless of internal representation).
         /// Returns false if node has no part indices.
@@ -984,7 +972,7 @@ public bool TryGetPartIndices([NotNullWhen(true)] out int[]? result)
         [Obsolete("Use custom attributes instead.")]
         public PersistentRef<V3f[]>? Velocities => null;
 
-#endregion
+        #endregion
 
         #region KdTree
 
@@ -1278,7 +1266,7 @@ private static Guid ComputeAndStoreKdTree(Storage storage, V3f[] ps)
             return kdId;
         }
 
-#endregion
+        #endregion
 
         #region Durable codec
 
diff --git a/src/Aardvark.Geometry.PointSet/Utils/StorageExtensions.cs b/src/Aardvark.Geometry.PointSet/Utils/StorageExtensions.cs
index 50a90de2..874671a6 100644
--- a/src/Aardvark.Geometry.PointSet/Utils/StorageExtensions.cs
+++ b/src/Aardvark.Geometry.PointSet/Utils/StorageExtensions.cs
@@ -25,6 +25,7 @@ You should have received a copy of the GNU Affero General Public License
 using System.Text;
 using System.Text.Json.Nodes;
 using Uncodium.SimpleStore;
+using static Aardvark.Base.IL.Constant;
 
 namespace Aardvark.Geometry.Points
 {
@@ -80,6 +81,18 @@ public static int[] BufferToIntArray(byte[] buffer)
 
         #endregion
 
+        #region int16[]
+
+        /// <summary>int16[] -> byte[]</summary>
+        public static byte[] Int16ArrayToBuffer(short[] data)
+            => ArrayToBuffer(data, sizeof(short), (bw, x) => bw.Write(x));
+
+        /// <summary>byte[] -> int16[]</summary>
+        public static short[] BufferToInt16Array(byte[] buffer)
+            => BufferToArray(buffer, sizeof(short), br => br.ReadInt16());
+
+        #endregion
+
         #region V2f[]
 
         /// <summary>V2f[] -> byte[]</summary>
@@ -292,14 +305,15 @@ public static void Add(this Storage storage, string key, Array data)
         {
             switch (data)
             {
-                case null: throw new ArgumentNullException(nameof(data));
-                case byte[] xs: storage.f_add(key, xs, () => xs); break;
-                case int[]  xs: storage.f_add(key, xs, () => Codec.IntArrayToBuffer(xs)); break;
-                case V2f[]  xs: storage.f_add(key, xs, () => Codec.V2fArrayToBuffer(xs)); break;
-                case V2d[]  xs: storage.f_add(key, xs, () => Codec.V2dArrayToBuffer(xs)); break;
-                case V3f[]  xs: storage.f_add(key, xs, () => Codec.V3fArrayToBuffer(xs)); break;
-                case V3d[]  xs: storage.f_add(key, xs, () => Codec.V3dArrayToBuffer(xs)); break;
-                case C4b[]  xs: storage.f_add(key, xs, () => Codec.C4bArrayToBuffer(xs)); break;
+                case null      : throw new ArgumentNullException(nameof(data));
+                case byte[]  xs: storage.f_add(key, xs, () => xs); break;
+                case int[]   xs: storage.f_add(key, xs, () => Codec.IntArrayToBuffer(xs)); break;
+                case short[] xs: storage.f_add(key, xs, () => Codec.Int16ArrayToBuffer(xs)); break;
+                case V2f[]   xs: storage.f_add(key, xs, () => Codec.V2fArrayToBuffer(xs)); break;
+                case V2d[]   xs: storage.f_add(key, xs, () => Codec.V2dArrayToBuffer(xs)); break;
+                case V3f[]   xs: storage.f_add(key, xs, () => Codec.V3fArrayToBuffer(xs)); break;
+                case V3d[]   xs: storage.f_add(key, xs, () => Codec.V3dArrayToBuffer(xs)); break;
+                case C4b[]   xs: storage.f_add(key, xs, () => Codec.C4bArrayToBuffer(xs)); break;
                 default: throw new Exception($"Type {data.GetType()} not supported.");
             }
         }
@@ -444,6 +458,10 @@ public static void Add(this Storage storage, string key, IList<V3f> data)
         public static void Add(this Storage storage, string key, int[] data)
             => storage.f_add(key, data, () => Codec.IntArrayToBuffer(data));
 
+        /// <summary></summary>
+        public static int[]? GetIntArray(this Storage storage, Guid key)
+            => GetIntArray(storage, key.ToString());
+
         /// <summary></summary>
         public static int[]? GetIntArray(this Storage storage, string key)
         {
@@ -476,6 +494,51 @@ public static (bool, int[]?) TryGetIntArray(this Storage storage, string key)
 
         #endregion
 
+        #region int16[]
+
+        /// <summary></summary>
+        public static void Add(this Storage storage, Guid key, short[] data) => Add(storage, key.ToString(), data);
+
+        /// <summary></summary>
+        public static void Add(this Storage storage, string key, short[] data)
+            => storage.f_add(key, data, () => Codec.Int16ArrayToBuffer(data));
+
+        /// <summary></summary>
+        public static short[]? GetInt16Array(this Storage storage, Guid key)
+            => GetInt16Array(storage, key.ToString());
+
+        /// <summary></summary>
+        public static short[]? GetInt16Array(this Storage storage, string key)
+        {
+            if (storage.HasCache && storage.Cache.TryGetValue(key, out object o)) return (short[])o;
+
+            var buffer = storage.f_get(key);
+            if (buffer == null) return null;
+            var data = Codec.BufferToInt16Array(buffer);
+
+            if (storage.HasCache)
+                storage.Cache.Add(key, data, buffer.Length, onRemove: default);
+
+            return data;
+        }
+
+        /// <summary></summary>
+        public static (bool, short[]?) TryGetInt16Array(this Storage storage, string key)
+        {
+            if (storage.HasCache && storage.Cache.TryGetValue(key, out object o))
+            {
+                return (true, (short[])o);
+            }
+            else
+            {
+                return (false, default);
+            }
+        }
+
+        public static bool TryGetInt16ArrayFromCache(this Storage storage, string key, [NotNullWhen(true)] out short[]? result) => TryGetFromCache(storage, key, out result);
+
+        #endregion
+
         #region C4b[]
 
         /// <summary></summary>
diff --git a/src/Apps/Viewer/Program.fs b/src/Apps/Viewer/Program.fs
index 6bda0503..35118d70 100644
--- a/src/Apps/Viewer/Program.fs
+++ b/src/Apps/Viewer/Program.fs
@@ -14,7 +14,7 @@ let main args =
     //view @"C:\Users\sm\Downloads\C_30DN2.LAZ.store" [File.readAllText @"C:\Users\sm\Downloads\C_30DN2.LAZ.key"] (Args.parse [||])
     //view @"C:\Users\sm\Downloads\test.store" ["128330b1-8761-4a07-b160-76bcd7e2f70a"; "ab2f6f76-7eae-47c9-82d1-ad28b816abb9"] (Args.parse [||])
     
-    let store = @"C:\bla\store\lowergetikum\data.bin"
+    let store = @"W:\Datasets\Vgm\Stores\lowergetikum 20230321.e57_0.01_2\data.uds"
     let key = Path.combine [System.IO.Path.GetDirectoryName store;"key.txt"] |> File.readAllText
     view store [key] (Args.parse [||])