diff --git a/glue_ar/common/volume_export_options.py b/glue_ar/common/volume_export_options.py
index bc17ba1..1e593a7 100644
--- a/glue_ar/common/volume_export_options.py
+++ b/glue_ar/common/volume_export_options.py
@@ -11,3 +11,4 @@ class ARIsosurfaceExportOptions(State):
 
 class ARVoxelExportOptions(State):
     opacity_cutoff = CallbackProperty(0.05)
+    opacity_resolution = CallbackProperty(0.01)
diff --git a/glue_ar/common/voxels.py b/glue_ar/common/voxels.py
index 7835656..c5f37e7 100644
--- a/glue_ar/common/voxels.py
+++ b/glue_ar/common/voxels.py
@@ -9,8 +9,9 @@
 from glue_ar.common.usd_builder import USDBuilder
 from glue_ar.common.volume_export_options import ARVoxelExportOptions
 from glue_ar.usd_utils import material_for_color
-from glue_ar.utils import BoundsWithResolution, alpha_composite, frb_for_layer, get_resolution, hex_to_components, \
-                          isomin_for_layer, isomax_for_layer, layer_color, unique_id, xyz_bounds
+from glue_ar.utils import BoundsWithResolution, alpha_composite, binned_opacity, clamp, clamped_opacity, \
+                          frb_for_layer, get_resolution, hex_to_components, isomin_for_layer, \
+                          isomax_for_layer, layer_color, unique_id, xyz_bounds
 
 from glue_ar.gltf_utils import add_points_to_bytearray, add_triangles_to_bytearray, \
                                clip_linear_transformations, index_mins, index_maxes
@@ -76,7 +77,8 @@ def add_voxel_layers_gltf(builder: GLTFBuilder,
     occupied_voxels = {}
 
     for layer_state, option in zip(layer_states, options):
-        opacity_cutoff = option.opacity_cutoff
+        opacity_cutoff = clamp(option.opacity_cutoff, 0, 1)
+        opacity_resolution = clamp(option.opacity_resolution, 0, 1)
         data = frb_for_layer(viewer_state, layer_state, bounds)
 
         isomin = isomin_for_layer(viewer_state, layer_state)
@@ -94,7 +96,7 @@ def add_voxel_layers_gltf(builder: GLTFBuilder,
 
         for indices in nonempty_indices:
             value = data[tuple(indices)]
-            adjusted_opacity = min(max(layer_state.alpha * opacity_factor * (value - isomin) / isorange, 0), 1)
+            adjusted_opacity = clamped_opacity(layer_state.alpha * opacity_factor * (value - isomin) / isorange)
             indices_tpl = tuple(indices)
             if indices_tpl in occupied_voxels:
                 current_color = occupied_voxels[indices_tpl]
@@ -137,7 +139,7 @@ def add_voxel_layers_gltf(builder: GLTFBuilder,
             mins=pt_mins,
             maxes=pt_maxes,
         )
-        rgba_tpl = tuple(rgba)
+        rgba_tpl = tuple(rgba[:3] + [binned_opacity(rgba[3], opacity_resolution)])
         if rgba_tpl in materials_map:
             material_index = materials_map[rgba_tpl]
         else:
@@ -191,7 +193,8 @@ def add_voxel_layers_usd(builder: USDBuilder,
     occupied_voxels = {}
 
     for layer_state, option in zip(layer_states, options):
-        opacity_cutoff = option.opacity_cutoff
+        opacity_cutoff = clamp(option.opacity_cutoff, 0, 1)
+        opacity_resolution = clamp(option.opacity_resolution, 0, 1)
         data = frb_for_layer(viewer_state, layer_state, bounds)
 
         isomin = isomin_for_layer(viewer_state, layer_state)
@@ -209,7 +212,7 @@ def add_voxel_layers_usd(builder: USDBuilder,
 
         for indices in nonempty_indices:
             value = data[tuple(indices)]
-            adjusted_opacity = min(max(layer_state.alpha * opacity_factor * (value - isomin) / isorange, 0), 1)
+            adjusted_opacity = clamped_opacity(layer_state.alpha * opacity_factor * (value - isomin) / isorange)
             indices_tpl = tuple(indices)
             if indices_tpl in occupied_voxels:
                 current_color = occupied_voxels[indices_tpl]
@@ -226,7 +229,7 @@ def add_voxel_layers_usd(builder: USDBuilder,
             continue
 
         center = tuple((index + 0.5) * side for index, side in zip(indices, clip_sides))
-        rgba_tpl = tuple(rgba)
+        rgba_tpl = tuple(rgba[:3] + [binned_opacity(rgba[3], opacity_resolution)])
         if rgba_tpl in materials_map:
             material = materials_map[rgba_tpl]
         else:
diff --git a/glue_ar/utils.py b/glue_ar/utils.py
index 645efb0..8174cc3 100644
--- a/glue_ar/utils.py
+++ b/glue_ar/utils.py
@@ -1,3 +1,4 @@
+from numbers import Number
 from os.path import abspath, dirname, join
 from uuid import uuid4
 from typing import Iterator, Literal, overload, Iterable, List, Optional, Tuple, Union
@@ -278,3 +279,16 @@ def get_resolution(viewer_state: Viewer3DState) -> int:
         pass
 
     return 256
+
+
+# TODO: What is the right typing here?
+def clamp(value: Number, minimum: Number, maximum: Number) -> Number:
+    return min(max(value, minimum), maximum)
+
+
+def clamped_opacity(opacity: float) -> float:
+    return clamp(opacity, 0, 1)
+
+
+def binned_opacity(raw_opacity: float, resolution: float) -> float:
+    return clamped_opacity(round(raw_opacity / resolution) * resolution)