diff --git a/block_nerf/block_nerf_model.py b/block_nerf/block_nerf_model.py
index 973d82d..bc70d84 100644
--- a/block_nerf/block_nerf_model.py
+++ b/block_nerf/block_nerf_model.py
@@ -109,8 +109,7 @@ def __init__(self, D=8, W=256, skips=[4],
             input_channel += in_channel_appearance
         if add_exposure:
             input_channel += in_channel_exposure
-        # 3层128
-        self.dir_encoding = nn.Sequential(  # RGB由dir,Exposure,Appearance决定
+        self.dir_encoding = nn.Sequential(
             nn.Linear(
                 input_channel,
                 W // 2
diff --git a/block_nerf/rendering.py b/block_nerf/rendering.py
index 7151d88..a260826 100644
--- a/block_nerf/rendering.py
+++ b/block_nerf/rendering.py
@@ -16,7 +16,7 @@ def get_cone_mean_conv(
     middle_t = (t0 + t1) / 2
     difference_t = (t1 - t0) / 2
     mean_t = difference_t ** 2 / 3 - 4 / 15 * (difference_t ** 4 * (12
-            * mean_t ** 2 - difference_t ** 2) / (3 * mean_t ** 2
+            * middle_t ** 2 - difference_t ** 2) / (3 * middle_t ** 2
             + difference_t ** 2) ** 2)
     variance_t = difference_t ** 2 / 3 - 4 / 15 * (difference_t ** 4
             * (12 * middle_t ** 2 - difference_t ** 2) / (3 * middle_t