diff --git a/nerfacc/volrend.py b/nerfacc/volrend.py
index 34ff1c0..fdb8cbe 100644
--- a/nerfacc/volrend.py
+++ b/nerfacc/volrend.py
@@ -88,11 +88,12 @@ def rendering(
 
     # Query sigma/alpha and color with gradients
     if rgb_sigma_fn is not None:
-        if t_starts.shape[0] != 0:
-            rgbs, sigmas = rgb_sigma_fn(t_starts, t_ends, ray_indices)
-        else:
-            rgbs = torch.empty((0, 3), device=t_starts.device)
-            sigmas = torch.empty((0,), device=t_starts.device)
+        rgbs, sigmas = rgb_sigma_fn(t_starts, t_ends, ray_indices)
+        # if t_starts.shape[0] != 0:
+        #     rgbs, sigmas = rgb_sigma_fn(t_starts, t_ends, ray_indices)
+        # else:
+        #     rgbs = torch.empty((0, 3), device=t_starts.device)
+        #     sigmas = torch.empty((0,), device=t_starts.device)
         assert rgbs.shape[-1] == 3, "rgbs must have 3 channels, got {}".format(
             rgbs.shape
         )
@@ -115,11 +116,12 @@ def rendering(
             "rgbs": rgbs,
         }
     elif rgb_alpha_fn is not None:
-        if t_starts.shape[0] != 0:
-            rgbs, alphas = rgb_alpha_fn(t_starts, t_ends, ray_indices)
-        else:
-            rgbs = torch.empty((0, 3), device=t_starts.device)
-            alphas = torch.empty((0,), device=t_starts.device)
+        rgbs, alphas = rgb_alpha_fn(t_starts, t_ends, ray_indices)
+        # if t_starts.shape[0] != 0:
+        #     rgbs, alphas = rgb_alpha_fn(t_starts, t_ends, ray_indices)
+        # else:
+        #     rgbs = torch.empty((0, 3), device=t_starts.device)
+        #     alphas = torch.empty((0,), device=t_starts.device)
         assert rgbs.shape[-1] == 3, "rgbs must have 3 channels, got {}".format(
             rgbs.shape
         )