diff --git a/slides/cours_19.md b/slides/cours_19.md
index ae4830a1b862c3badbecfae415cf754b76175ca4..57d323959ce4d50a7b71452572019a754df3ed65 100644
--- a/slides/cours_19.md
+++ b/slides/cours_19.md
@@ -365,7 +365,7 @@ Son équivalent tri-dimensionnel est l'octree (chaque noeud a 8 enfants ou aucun
```{.mermaid format=pdf width=400 loc=figs/}
graph TD;
- id0((0))-->id1((0));
+ id0(( ))-->id1((0));
id0-->id2(( ));
id0-->id3(( ));
id0-->id4(( ));
@@ -381,8 +381,14 @@ graph TD;
id4-->id14((0))
id4-->id15((1))
id4-->id16(( ))
- style id8 fill:#fff,stroke:#fff
- style id13 fill:#fff,stroke:#fff
+ id5-->id17((0))
+ id5-->id18((1))
+ id5-->id19((1))
+ id5-->id20((0))
+ id16-->id21((1))
+ id16-->id22((1))
+ id16-->id23((1))
+ id16-->id24((0))
```
::::
diff --git a/slides/figs/board_blacked_parts.svg b/slides/figs/board_blacked_parts.svg
new file mode 100644
index 0000000000000000000000000000000000000000..50d056aa58cc54b474049bfa27e4064318724b5a
--- /dev/null
+++ b/slides/figs/board_blacked_parts.svg
@@ -0,0 +1,163 @@
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