From 07beb326fa7221eba55372ea511137ef099a15ea Mon Sep 17 00:00:00 2001
From: Hui Wang <wanghehv@sjtu.edu.cn>
Date: Wed, 12 Apr 2023 13:55:47 +0000
Subject: [PATCH] Update environment_lighting.md

---
 docs/pathtracer/environment_lighting.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/docs/pathtracer/environment_lighting.md b/docs/pathtracer/environment_lighting.md
index 684ca8b..785830f 100644
--- a/docs/pathtracer/environment_lighting.md
+++ b/docs/pathtracer/environment_lighting.md
@@ -8,6 +8,10 @@
 <video width="750" height="500" controls><source src="videos/Task7_EnvMap.mp4" type="video/mp4"></video>
 ![](./videos/Task7_EnvMap.mp4)
 
+**Note**: The phi/theta direction in the video may be confusing, so please refer to the axis direction in the following figure. We will fix the video soon.
+
+![envmap_angle_figure](./figures/envmap_angle_figure.png)
+
 The final task of this assignment will be to implement a new type of light source: an infinite environment light. An environment light is a light that supplies incident radiance (really, the light intensity dPhi/dOmega) from all directions on the sphere. Rather than using a predefined collection of explicit lights, an environment light is a capture of the actual incoming light from some real-world scene; rendering using environment lighting can be quite striking.
 
 The intensity of incoming light from each direction is defined by a texture map parameterized by phi and theta, as shown below.
-- 
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