Adds GenerateHeatmap transform

Adds a `GenerateHeatmap` transform to generate heatmaps from point data.

This transform creates heatmaps from point data, validating that the dtype
is a floating-point type.

Signed-off-by: sewon.jeon <[email protected]>

Author: eclipse0922

monai/transforms/__init__.py

@@ -293,6 +293,7 @@
     AsDiscrete,
     DistanceTransformEDT,
     FillHoles,
+    GenerateHeatmap,
     Invert,
     KeepLargestConnectedComponent,
     LabelFilter,
@@ -319,6 +320,9 @@
     FillHolesD,
     FillHolesd,
     FillHolesDict,
+    GenerateHeatmapd,
+    GenerateHeatmapD,
+    GenerateHeatmapDict,
     InvertD,
     Invertd,
     InvertDict,

monai/transforms/post/array.py

@@ -799,6 +799,9 @@ def __init__(
         self.normalize = normalize
         self.torch_dtype = get_equivalent_dtype(dtype, torch.Tensor)
         self.numpy_dtype = get_equivalent_dtype(dtype, np.ndarray)
+        # Validate that dtype is floating-point for meaningful Gaussian values
+        if self.torch_dtype not in (torch.float16, torch.float32, torch.float64, torch.bfloat16):
+            raise ValueError(f"dtype must be a floating-point type, got {self.torch_dtype}")
         self.spatial_shape = None if spatial_shape is None else tuple(int(s) for s in spatial_shape)
 
     def __call__(self, points: NdarrayOrTensor, spatial_shape: Sequence[int] | None = None) -> NdarrayOrTensor: