Clean up presenter notes

src/index.html

@@ -29,7 +29,7 @@
               - Help _others_ build robots
             </aside>
           </section>
-          <section data-background-iframe="https://www.youtube-nocookie.com/embed/xiDS58Htuh4?autoplay=1&start=24">
+          <section data-background-iframe="https://www.youtube-nocookie.com/embed/xiDS58Htuh4?autoplay=1&start=25">
             <aside class="notes" data-markdown>
               - I volunteer for Student Robotics
               - Charity to help students get into STEM
@@ -58,7 +58,7 @@
           <section>
             <h2 class="r-fit-text">How do fiducial markers work?</h2>
             <aside class="notes" data-markdown>
-              - How does it actually _work_?
+              - How do they work?
             </aside>
           </section>
         </section>
@@ -95,6 +95,7 @@
             - Markers are squares
               - Well, quadralaterals
             - Find collections with 4 sides
+              - Filter out rectangles, nested collections etc
           </aside>
         </section>
         <section data-background-image="https://docs.opencv.org/4.x/singlemarkersoriginal.jpg">
@@ -106,7 +107,6 @@
               - Make our lives easier!
             - Skew the image a bit
               - Same process used for those paper scanning apps
-            - Markers are now always straight on
           </aside>
         </section>
         <section data-background-image="https://docs.opencv.org/4.x/bitsextraction2.png" data-background-size="contain">
@@ -117,7 +117,7 @@
             - We know how many pixels are in a marker
               - Divide it down into cells
               - Add some margins in case we're slightly off
-            - Average the remaining pixels in each cell
+            - If it's over 50% white, it's a 1
             - Convert into 2D list
           </aside>
         </section>
@@ -125,7 +125,7 @@
             <h2 class="r-fit-text">6. Decoding</h2>
             <aside class="notes" data-markdown>
               - Just 1s and 0s now
-              - 7x7 markers have 2041 combinations
+              - Keen eyed may have noticed 7x7 markers have 2041 combinations
                 - There are only ~255 possible combinations
               - Error checks
                 - Single pixel flips can be corrected
@@ -141,6 +141,7 @@
                 - Which way is it facing?
               - We know where the corners are
                 - We can get the angle from that
+                - Much like when we removed distortion
                 - If we know the size of the marker, we can calculate its distance
               - Some calibration per camera model is required
                 - Done once upfront
@@ -148,7 +149,6 @@
                 - _complicated maths_
                 - `solvePnP` in OpenCV (entertaining name)
                 - "Perspective 'n' Point"
-                - Requires calibration for each camera model
               - With simpler maths, can be turned into angles, distances etc
             </aside>
         </section>
@@ -215,7 +215,7 @@
               from zoloto import MarkerType
               from zoloto.cameras import Camera
 
-              with Camera(marker_type=MarkerType.ARUCO_6X6) as camera:
+              with Camera(marker_type=MarkerType.APRILTAG_36H11) as camera:
                 for frame in camera:
                   print(
                     "Markers I can see:",