here we go

app.py

@@ -53,7 +53,7 @@ Pan and zoom to the desired location on the map. Then, use the map tools to draw
 built = "https://huggingface.co/datasets/boettiger-lab/yellowstone/resolve/main/diffs_cog.tif"
 
 
-m = leafmap.Map(center=(-110.6, 45.45), zoom=10)
+m = leafmap.Map(center=(-110.6, 45.45), zoom=8)
 m.add_basemap("Esri.NatGeoWorldMap")
 
 ## Map controls sidebar
@@ -66,9 +66,10 @@ with st.sidebar:
 
     selection = st.radio("Data", cog_layers)
     cog = cog_layers[selection]
-    m.add_cog_layer(cog, palette="reds", name=selection,
-                    transparent_bg=True, opacity = 0.8, 
-                    zoom_to_layer=False)
+    m.add_cog_layer(cog, name=selection, palette="reds",
+                    opacity = 0.3, 
+                    transparent_bg = True,
+                    zoom_to_layer=True)
 
 
 st_data = m.to_streamlit(height=400, bidirectional=True)
@@ -79,10 +80,12 @@ if polygon is not None:
     gdf = read_polygon(polygon)
     x = extract_geom(gdf, cog).fillna(0)    
     count = x.count()
+    impact_pixels = x.sum()
     area = round(float(area_hectares(gdf)))
+    impact_area = area * impact_pixels / count
     carbon_total = round(float(x.mean()) * area) # no, mean does not include zeros
-    col2, col3 = st.columns(3)
-    col2.metric(label=f"Area", value=f"{area:,} Hectares")
+    col2, col3 = st.columns(2)
+    col2.metric(label=f"Area", value=f"{impact_area:,.2f} Hectares")
     col3.metric(label=f"pixels", value=f"{count:,}")