Update README.md

README.md

@@ -6,21 +6,38 @@ Only annotate the upper half of the body.
 
 ## Annotation Rule
 
-* Annotate **upper half of the person**, as tight as possible
+* Annotate **upper half of the body**, as tight as possible
   * Thanh's gut feeling: "It will loosen up after training"
 
+* Visibility rule
+  Only annotate if **all** of these rules are satisfied
+
+  * Head must be visible
+  * The visible part of the upper half of the body must be larger than 50% of the upper body
+    * Example: if the stomach is not visible, the person can still be annotated, because the stomach usually only takes up 1/3 the size of the upper body, so the visible part is 2/3
+  * The person must not be too small
+
 * Bounding box rule
-  * Bottom edge touches the straight belt/hip:
+  * Bottom edge:
+    * Aligns with the horizontal belt line:
   
       ![Straight belt](http://192.168.0.101:8929/nvmnghia/cvat-annotation-rule/raw/master/straight%20belt.png)
 
-  * Bottom edge touches the top point of the oblique belt/hip
+    * Touches the top point of the oblique belt line:
+
+      ![Oblique belt](http://192.168.0.101:8929/nvmnghia/cvat-annotation-rule/raw/master/oblique%20belt.png)
 
-      ![Oblique belt](http://192.168.0.101:8929/nvmnghia/cvat-annotation-rule/raw/c409536b319bff3e6c7bf69fc20404669cf85d84/oblique%20belt.png)
+  * If some parts of the upper half are hidden (by shelves,...), **imagine the belt line** and annotate
+    * The above rules of "straight belt" and "oblique belt" still apply
+
+  * Top edge touches the head
+
+  * Side edges:
+    * If the person is straight up: Side edges must touch the top notch of the shoulders, not the whole arm, and
+    * If the person is oblique: Side edges must touch the furthest point of the body, meaning that background in this case is acceptable:
+
+    ![Oblique body](http://192.168.0.101:8929/nvmnghia/cvat-annotation-rule/raw/master/oblique%20standing.png)
 
   * Height must be more than 1/8 of the frame's height
+    * Use CVAT's grid feature
 
-* Visibility rule
-  * Head must be visible
-  * The visible part of the upper half must be larger than 50% of the whole upper part
-  * The person must not be too small