diff --git a/tsd/src/tsd/io/importers/import_NVDB.cpp b/tsd/src/tsd/io/importers/import_NVDB.cpp
index 53e7433d..89750231 100644
--- a/tsd/src/tsd/io/importers/import_NVDB.cpp
+++ b/tsd/src/tsd/io/importers/import_NVDB.cpp
@@ -30,6 +30,34 @@ SpatialFieldRef import_NVDB(Scene &scene, const char *filepath)
   try {
     auto grid = nanovdb::io::readGrid(filepath);
     auto metadata = grid.gridMetaData();
+
+    bool hasActiveVoxels = false;
+    switch (metadata->gridType()) {
+    case nanovdb::GridType::Fp4:
+      hasActiveVoxels = grid.grid<nanovdb::Fp4>()->activeVoxelCount() > 0;
+      break;
+    case nanovdb::GridType::Fp8:
+      hasActiveVoxels = grid.grid<nanovdb::Fp8>()->activeVoxelCount() > 0;
+      break;
+    case nanovdb::GridType::Fp16:
+      hasActiveVoxels = grid.grid<nanovdb::Fp16>()->activeVoxelCount() > 0;
+      break;
+    case nanovdb::GridType::FpN:
+      hasActiveVoxels = grid.grid<nanovdb::FpN>()->activeVoxelCount() > 0;
+      break;
+    case nanovdb::GridType::Float:
+      hasActiveVoxels = grid.grid<float>()->activeVoxelCount() > 0;
+      break;
+    default:
+      break;
+    }
+
+    if (!hasActiveVoxels) {
+      logStatus("[import_NVDB] no active voxels, skipping '%s'", filepath);
+      scene.removeObject(field.data());
+      return {};
+    }
+
     if (!metadata->hasMinMax()) {
       switch (metadata->gridType()) {
       case nanovdb::GridType::Fp4: {
diff --git a/tsd/src/tsd/io/importers/import_USD.cpp b/tsd/src/tsd/io/importers/import_USD.cpp
index e30ce42f..2f1b2620 100644
--- a/tsd/src/tsd/io/importers/import_USD.cpp
+++ b/tsd/src/tsd/io/importers/import_USD.cpp
@@ -910,7 +910,8 @@ static void import_usd_volume(Scene &scene,
   VolumeTransferFunction tf = get_volume_transfer_function(prim);
 
   ArrayRef colorArray;
-  math::float2 valueRange;
+  // Default to the field's value range to avoid undefined ranges.
+  math::float2 valueRange = field->computeValueRange();
 
   // Create a volume node and assign the field, color map, and value range
   auto [inst, volume] = scene.insertNewChildObjectNode<Volume>(
@@ -922,7 +923,8 @@ static void import_usd_volume(Scene &scene,
     // Use transfer function from USD material
     colorArray = scene.createArray(ANARI_FLOAT32_VEC4, tf.colors.size());
     colorArray->setData(tf.colors.data(), tf.colors.size());
-    valueRange = tf.domain;
+    if (tf.domain.x < tf.domain.y)
+      valueRange = tf.domain;
 
     // Create opacity control points from USD transfer function
     std::vector<math::float2> opacityControlPoints;