diff --git a/rtiow/src/scenes/bench.rs b/rtiow/src/scenes/bench.rs
index 5eaccf2..c7774a2 100644
--- a/rtiow/src/scenes/bench.rs
+++ b/rtiow/src/scenes/bench.rs
@@ -1,6 +1,7 @@
 use rand;
 use rand::Rng;
 
+use bvh::BVH;
 use camera::Camera;
 use hitable::Hit;
 use hitable_list::HitableList;
@@ -38,19 +39,28 @@ pub fn new(opt: &Opt) -> Scene {
             let g = rng.gen_range::<f32>(0., 1.);
             let b = rng.gen_range::<f32>(0., 1.);
 
+            let x_pos = (x - len / 2) as f32 + rng.gen_range(-0.1, 0.1);
+            let z_pos = (z - len / 2) as f32 + rng.gen_range(-0.1, 0.1);
+
             grid.push(Box::new(Sphere::new(
-                Vec3::new((x - len / 2) as f32, 0., (z - len / 2) as f32),
+                Vec3::new(x_pos, 0., z_pos),
                 0.5,
                 Box::new(Lambertian::new(Vec3::new(r, g, b))),
             )));
         }
     }
-    let use_kdtree = true;
     let world: Box<Hit>;
-    if use_kdtree {
-        let kdtree = KDTree::new(grid, time_min, time_max);
-        //trace!(target: "k-d tree", "World {}", kdtree);
-        world = Box::new(kdtree);
+    if opt.use_accel {
+        let use_kd = true;
+        if use_kd {
+            let kdtree = KDTree::new(grid, time_min, time_max);
+            trace!("k-d tree world {}", kdtree);
+            world = Box::new(kdtree);
+        } else {
+            let bvh = BVH::new(grid, time_min, time_max);
+            trace!("BVH world {}", bvh);
+            world = Box::new(bvh);
+        }
     } else {
         world = Box::new(HitableList::new(grid));
     }