diff --git a/ovr/devices/ospray/device_impl.cpp b/ovr/devices/ospray/device_impl.cpp
index 85a7111..2947a8e 100644
--- a/ovr/devices/ospray/device_impl.cpp
+++ b/ovr/devices/ospray/device_impl.cpp
@@ -248,6 +248,18 @@ DeviceOSPRay::Impl::create_ospray_geometry(scene::Geometry::GeometryTriangles ha
   return mesh;
 }
 
+OSPGeometry 
+DeviceOSPRay::Impl::create_ospray_geometry(scene::Geometry::GeometrySpheres handler) {
+  OSPGeometry sphere = ospNewGeometry("sphere");
+  assert(handler.position->type == ovr::VALUE_TYPE_FLOAT3);
+  auto position = ospNewSharedData1D(handler.position->data(), OSP_VEC3F, handler.position->dims.v);
+  ospSetObject(sphere, "sphere.position", position);
+  ospSetFloat(sphere, "radius", handler.radius);
+  ospCommit(sphere);
+  ospRelease(position);
+  return sphere;
+}
+
 OSPGeometry
 DeviceOSPRay::Impl::create_ospray_geometry(scene::Geometry::GeometryIsosurfaces handler) {
   OSPGeometry geom = ospNewGeometry("isosurface");
@@ -262,6 +274,7 @@ OSPGeometry
 DeviceOSPRay::Impl::create_ospray_geometry(scene::Geometry handler) {
   switch (handler.type) {
   case scene::Geometry::TRIANGLES_GEOMETRY:  return create_ospray_geometry(handler.triangles);
+  case scene::Geometry::SPHERES_GEOMETRY:    return create_ospray_geometry(handler.spheres);
   case scene::Geometry::ISOSURFACE_GEOMETRY: return create_ospray_geometry(handler.isosurfaces);
   default: throw std::runtime_error("unknown geometry type");
   }
diff --git a/ovr/devices/ospray/device_impl.h b/ovr/devices/ospray/device_impl.h
index c5d02f9..79a8361 100644
--- a/ovr/devices/ospray/device_impl.h
+++ b/ovr/devices/ospray/device_impl.h
@@ -62,6 +62,7 @@ struct DeviceOSPRay::Impl {
 
   OSPGeometry create_ospray_geometry(scene::Geometry::GeometryTriangles handler);
   OSPGeometry create_ospray_geometry(scene::Geometry::GeometryIsosurfaces handler);
+  OSPGeometry create_ospray_geometry(scene::Geometry::GeometrySpheres handler);
   OSPGeometry create_ospray_geometry(scene::Geometry handler);
   
   OSPTexture create_ospray_texture(scene::Texture::TransferFunctionTexture handler);
diff --git a/ovr/scene.h b/ovr/scene.h
index c741df1..74d1fa3 100644
--- a/ovr/scene.h
+++ b/ovr/scene.h
@@ -273,7 +273,7 @@ struct Material {
     vec3f kd = vec3f(0.8f); // diffuse reflectivity
     vec3f ks = vec3f(0.0f); // specular reflectivity
     float ns = 10.f; // specular exponent
-    float d = 1.f; // opacity
+    float d = 2.f; // opacity
     vec3f tf = vec3f(1.f); // transparency filter
     // texture maps
     int32_t map_kd = -1;
@@ -284,6 +284,7 @@ struct Material {
 struct Geometry {
   enum {
     TRIANGLES_GEOMETRY,
+    SPHERES_GEOMETRY,
     ISOSURFACE_GEOMETRY,
   } type;
 
@@ -297,6 +298,11 @@ struct Geometry {
     } verts, faces;
   } triangles;
 
+  struct GeometrySpheres {
+    array_1d_float3_t position;
+    float radius = 0.01f;
+  } spheres;
+
   struct GeometryIsosurfaces {
     int32_t volume_texture;
     std::vector<float> isovalues;