diff --git a/src/batdetect2/plotting/clip_annotations.py b/src/batdetect2/plotting/clip_annotations.py
index ca4665b..b0b33a5 100644
--- a/src/batdetect2/plotting/clip_annotations.py
+++ b/src/batdetect2/plotting/clip_annotations.py
@@ -4,7 +4,9 @@ from matplotlib.axes import Axes
 from soundevent import data, plot
 
 from batdetect2.plotting.clips import plot_clip
+from batdetect2.plotting.common import create_ax
 from batdetect2.typing.preprocess import PreprocessorProtocol
+from batdetect2.typing.targets import TargetProtocol
 
 __all__ = [
     "plot_clip_annotation",
@@ -43,3 +45,31 @@ def plot_clip_annotation(
         facecolor="none" if not fill else None,
     )
     return ax
+
+
+def plot_anchor_points(
+    clip_annotation: data.ClipAnnotation,
+    targets: TargetProtocol,
+    figsize: Optional[Tuple[int, int]] = None,
+    ax: Optional[Axes] = None,
+    size: int = 1,
+    color: str = "red",
+    marker: str = "x",
+    alpha: float = 1,
+) -> Axes:
+    ax = create_ax(ax=ax, figsize=figsize)
+
+    positions = []
+
+    for sound_event in clip_annotation.sound_events:
+        if not targets.filter(sound_event):
+            continue
+
+        sound_event = targets.transform(sound_event)
+
+        position, _ = targets.encode_roi(sound_event)
+        positions.append(position)
+
+    X, Y = zip(*positions)
+    ax.scatter(X, Y, s=size, c=color, marker=marker, alpha=alpha)
+    return ax
diff --git a/src/batdetect2/plotting/common.py b/src/batdetect2/plotting/common.py
index 9a8b930..f9459a9 100644
--- a/src/batdetect2/plotting/common.py
+++ b/src/batdetect2/plotting/common.py
@@ -1,6 +1,6 @@
 """General plotting utilities."""
 
-from typing import Optional, Tuple
+from typing import Optional, Tuple, Union
 
 import matplotlib.pyplot as plt
 import numpy as np
@@ -25,7 +25,7 @@ def create_ax(
 
 
 def plot_spectrogram(
-    spec: torch.Tensor,
+    spec: Union[torch.Tensor, np.ndarray],
     start_time: float,
     end_time: float,
     min_freq: float,
@@ -34,12 +34,15 @@ def plot_spectrogram(
     figsize: Optional[Tuple[int, int]] = None,
     cmap="gray",
 ) -> axes.Axes:
+    if isinstance(spec, torch.Tensor):
+        spec = spec.numpy()
+
     ax = create_ax(ax=ax, figsize=figsize)
 
     ax.pcolormesh(
-        np.linspace(start_time, end_time, spec.shape[-1], endpoint=False),
-        np.linspace(min_freq, max_freq, spec.shape[-2], endpoint=False),
-        spec.numpy(),
+        np.linspace(start_time, end_time, spec.shape[-1] + 1, endpoint=True),
+        np.linspace(min_freq, max_freq, spec.shape[-2] + 1, endpoint=True),
+        spec,
         cmap=cmap,
     )
     return ax
diff --git a/src/batdetect2/train/labels.py b/src/batdetect2/train/labels.py
index 3dd9da6..176ee81 100644
--- a/src/batdetect2/train/labels.py
+++ b/src/batdetect2/train/labels.py
@@ -62,7 +62,7 @@ class LabelConfig(BaseConfig):
         diffuse targets.
     """
 
-    sigma: float = 3.0
+    sigma: float = 2.0
 
 
 def build_clip_labeler(
@@ -174,7 +174,7 @@ def generate_clip_label(
 
 
 def map_to_pixels(x, size, min_val, max_val) -> int:
-    return int(np.floor(np.interp(x, [min_val, max_val], [0, size])))
+    return int(np.interp(x, [min_val, max_val], [0, size]))
 
 
 def generate_heatmaps(