Add https://youtu.be/96NkhsV-W1U to docs and `heatmaps` fix (#7944)

Co-authored-by: UltralyticsAssistant <web@ultralytics.com>
Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

docs/en/guides/index.md

@@ -10,6 +10,17 @@ Welcome to the Ultralytics' YOLO 🚀 Guides! Our comprehensive tutorials cover
 
 Whether you're a beginner or an expert in deep learning, our tutorials offer valuable insights into the implementation and optimization of YOLO for your computer vision projects. Let's dive in!
 
+<p align="center">
+  <br>
+  <iframe width="720" height="405" src="https://www.youtube.com/embed/96NkhsV-W1U"
+    title="YouTube video player" frameborder="0"
+    allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share"
+    allowfullscreen>
+  </iframe>
+  <br>
+  <strong>Watch:</strong> Ultralytics YOLOv8 Guides Overview
+</p>
+
 ## Guides
 
 Here's a compilation of in-depth guides to help you master different aspects of Ultralytics YOLO.

ultralytics/solutions/heatmap.py

@@ -167,9 +167,10 @@ class Heatmap:
         """
         self.im0 = im0
         if tracks[0].boxes.id is None:
+            self.heatmap = np.zeros((int(self.imh), int(self.imw)), dtype=np.float32)
             if self.view_img and self.env_check:
                 self.display_frames()
-            return
+            return im0
         self.heatmap *= self.decay_factor  # decay factor
         self.extract_results(tracks)
         self.annotator = Annotator(self.im0, self.count_txt_thickness, None)

ultralytics/solutions/object_counter.py

@@ -256,7 +256,7 @@ class ObjectCounter:
         if tracks[0].boxes.id is None:
             if self.view_img:
                 self.display_frames()
-            return
+            return im0
         self.extract_and_process_tracks(tracks)
 
         if self.view_img:

ultralytics/solutions/speed_estimation.py

@@ -164,7 +164,7 @@ class SpeedEstimator:
         if tracks[0].boxes.id is None:
             if self.view_img and self.env_check:
                 self.display_frames()
-            return
+            return im0
         self.extract_tracks(tracks)
 
         self.annotator = Annotator(self.im0, line_width=2)