diff --git a/main.py b/main.py
index 19f825c7..5ef8b833 100644
--- a/main.py
+++ b/main.py
@@ -70,8 +70,8 @@
 
     if opt.O:
         opt.fp16 = True
-        opt.cuda_ray = True
         opt.dir_text = True
+        opt.cuda_ray = True
     elif opt.O2:
         opt.fp16 = True
         opt.dir_text = True
diff --git a/nerf/renderer.py b/nerf/renderer.py
index 005fc7d4..64dd2733 100644
--- a/nerf/renderer.py
+++ b/nerf/renderer.py
@@ -323,7 +323,7 @@ def run(self, rays_o, rays_d, num_steps=128, upsample_steps=128, light_d=None, a
         # random sample light_d if not provided
         if light_d is None:
             # gaussian noise around the ray origin, so the light always face the view dir (avoid dark face)
-            light_d = - (rays_o[0] + torch.randn(3, device=device, dtype=torch.float))
+            light_d = (rays_o[0] + torch.randn(3, device=device, dtype=torch.float))
             light_d = safe_normalize(light_d)
 
         #print(f'nears = {nears.min().item()} ~ {nears.max().item()}, fars = {fars.min().item()} ~ {fars.max().item()}')
@@ -457,7 +457,7 @@ def run_cuda(self, rays_o, rays_d, dt_gamma=0, light_d=None, ambient_ratio=1.0,
         # random sample light_d if not provided
         if light_d is None:
             # gaussian noise around the ray origin, so the light always face the view dir (avoid dark face)
-            light_d = - (rays_o[0] + torch.randn(3, device=device, dtype=torch.float))
+            light_d = (rays_o[0] + torch.randn(3, device=device, dtype=torch.float))
             light_d = safe_normalize(light_d)
 
         results = {}