Add ensure_numerical call for USDZ colormap attribute values.

glue_ar/common/scatter_usd.py

@@ -1,5 +1,6 @@
 from collections import defaultdict
 from typing import List, Optional, Tuple
+from glue.utils.array import ensure_numerical
 
 from glue_vispy_viewers.scatter.layer_state import ScatterLayerState
 from glue_vispy_viewers.scatter.viewer_state import Vispy3DViewerState
@@ -118,7 +119,7 @@ def add_scatter_layer_usd(
         cmap = layer_state.cmap
         cmap_attr = "cmap_attribute" if vispy_layer_state else "cmap_att"
         cmap_att = getattr(layer_state, cmap_attr)
-        cmap_vals = layer_state.layer[cmap_att][mask]
+        cmap_vals = ensure_numerical(layer_state.layer[cmap_att][mask])
         crange = layer_state.cmap_vmax - layer_state.cmap_vmin
         normalized = [max(min((cval - layer_state.cmap_vmin) / crange, 1), 0) for cval in cmap_vals]
         colors = [tuple(int(256 * c) for c in cmap(norm)[:3]) for norm in normalized]