diff --git a/map2loop/project.py b/map2loop/project.py
index 29f4d9e7..12943117 100644
--- a/map2loop/project.py
+++ b/map2loop/project.py
@@ -334,16 +334,16 @@ def sample_map_data(self):
         Use the samplers to extract points along polylines or unit boundaries
         """
         self.geology_samples = self.samplers[Datatype.GEOLOGY].sample(
-            self.map_data.get_map_data(Datatype.GEOLOGY)
+            self.map_data.get_map_data(Datatype.GEOLOGY), self.map_data
         )
         self.structure_samples = self.samplers[Datatype.STRUCTURE].sample(
-            self.map_data.get_map_data(Datatype.STRUCTURE)
+            self.map_data.get_map_data(Datatype.STRUCTURE), self.map_data
         )
         self.fault_samples = self.samplers[Datatype.FAULT].sample(
-            self.map_data.get_map_data(Datatype.FAULT)
+            self.map_data.get_map_data(Datatype.FAULT), self.map_data
         )
         self.fold_samples = self.samplers[Datatype.FOLD].sample(
-            self.map_data.get_map_data(Datatype.FOLD)
+            self.map_data.get_map_data(Datatype.FOLD), self.map_data
         )
 
     def extract_geology_contacts(self):
@@ -617,7 +617,7 @@ def save_into_projectfile(self):
         # Save structural information
         observations = numpy.zeros(len(self.structure_samples), LPF.stratigraphicObservationType)
         observations["layer"] = "s0"
-        observations["layerId"] = self.structure_samples["ID"]
+        observations["layerId"] = self.structure_samples["layerID"]
         observations["easting"] = self.structure_samples["X"]
         observations["northing"] = self.structure_samples["Y"]
         # observations["altitude"] = self.structure_samples["Z"]
diff --git a/map2loop/sampler.py b/map2loop/sampler.py
index ca5c6f66..73ad0876 100644
--- a/map2loop/sampler.py
+++ b/map2loop/sampler.py
@@ -4,6 +4,9 @@
 import pandas
 import shapely
 import numpy
+from .m2l_enums import Datatype
+from .mapdata import MapData
+from typing import Optional
 
 
 class Sampler(ABC):
@@ -31,12 +34,14 @@ def type(self):
 
     @beartype.beartype
     @abstractmethod
-    def sample(self, map_data: geopandas.GeoDataFrame) -> pandas.DataFrame:
+    def sample(
+        self, spatial_data: geopandas.GeoDataFrame, map_data: Optional[MapData] = None
+    ) -> pandas.DataFrame:
         """
         Execute sampling method (abstract method)
 
         Args:
-            map_data (geopandas.GeoDataFrame): data frame to sample
+            spatial_data (geopandas.GeoDataFrame): data frame to sample
 
         Returns:
             pandas.DataFrame: data frame containing samples
@@ -64,19 +69,24 @@ def __init__(self, decimation: int = 1):
         self.decimation = decimation
 
     @beartype.beartype
-    def sample(self, map_data: geopandas.GeoDataFrame) -> pandas.DataFrame:
+    def sample(
+        self, spatial_data: geopandas.GeoDataFrame, map_data: Optional[MapData] = None
+    ) -> pandas.DataFrame:
         """
         Execute sample method takes full point data, samples the data and returns the decimated points
 
         Args:
-            map_data (geopandas.GeoDataFrame): the data frame to sample
+            spatial_data (geopandas.GeoDataFrame): the data frame to sample
 
         Returns:
             pandas.DataFrame: the sampled data points
         """
-        data = map_data.copy()
+        data = spatial_data.copy()
         data["X"] = data.geometry.x
         data["Y"] = data.geometry.y
+        data["layerID"] = geopandas.sjoin(
+            data, map_data.get_map_data(Datatype.GEOLOGY), how='left'
+        )['index_right']
         data.reset_index(drop=True, inplace=True)
         return pandas.DataFrame(data[:: self.decimation].drop(columns="geometry"))
 
@@ -102,19 +112,21 @@ def __init__(self, spacing: float = 50.0):
         self.spacing = spacing
 
     @beartype.beartype
-    def sample(self, map_data: geopandas.GeoDataFrame) -> pandas.DataFrame:
+    def sample(
+        self, spatial_data: geopandas.GeoDataFrame, map_data: Optional[MapData] = None
+    ) -> pandas.DataFrame:
         """
         Execute sample method takes full point data, samples the data and returns the sampled points
 
         Args:
-            map_data (geopandas.GeoDataFrame): the data frame to sample (must contain column ["ID"])
+            spatial_data (geopandas.GeoDataFrame): the data frame to sample (must contain column ["ID"])
 
         Returns:
             pandas.DataFrame: the sampled data points
         """
         schema = {"ID": str, "X": float, "Y": float}
         df = pandas.DataFrame(columns=schema.keys()).astype(schema)
-        for _, row in map_data.iterrows():
+        for _, row in spatial_data.iterrows():
             if type(row.geometry) is shapely.geometry.multipolygon.MultiPolygon:
                 targets = row.geometry.boundary.geoms
             elif type(row.geometry) is shapely.geometry.polygon.Polygon:
@@ -133,7 +145,7 @@ def sample(self, map_data: geopandas.GeoDataFrame) -> pandas.DataFrame:
                 points = [target.interpolate(distance) for distance in distances]
                 df2["X"] = [point.x for point in points]
                 df2["Y"] = [point.y for point in points]
-                if "ID" in map_data.columns:
+                if "ID" in spatial_data.columns:
                     df2["ID"] = row["ID"]
                 else:
                     df2["ID"] = 0