push formulas

app.py

@@ -43,13 +43,18 @@ with cols[1]:
 ############################################
 # Hyperparameters
 ############################################        
-st.write("<h3><div style='text-align: center;'>User Inputs</div></h3>", unsafe_allow_html=True)
+st.write("<h2><div style='text-align: center;'>User Inputs</div></h2>", unsafe_allow_html=True)
 
 st.write("Select the vegetation indices to calculate:")
 all_veg_indices = ["NDVI", "EVI", "EVI2"]
+formulas = {
+    "NDVI": r"$\frac{NIR - Red}{NIR + Red}$",
+    "EVI": r"$G \times \frac{NIR - Red}{NIR + C1 \times Red - C2 \times Blue + L}$",
+    "EVI2": r"$G \times \frac{NIR - Red}{NIR + L + C \times Red}$",
+}
 veg_indices = []
 for veg_index in all_veg_indices:
-    if st.checkbox(veg_index, value=True):
+    if st.checkbox(f"{veg_index} = {formulas[veg_index]}", value=True):
         veg_indices.append(veg_index)
 
 st.write("Select the parameters for the EVI/EVI2 calculation (default is as per EVI's Wikipedia page)")
@@ -110,7 +115,7 @@ def add_indices(image, nir_band, red_band, blue_band):
     ndvi = (numerator).divide(nir.add(red)).rename("NDVI").clamp(-1, 1)
     # EVI formula taken from: https://en.wikipedia.org/wiki/Enhanced_vegetation_index 
     
-    denominator = nir.add(red.multiply(evi_vars['C1'])).subtract(blue.multiply(evi_vars['C2'])).add(evi_vars['L']).add(0.1)
+    denominator = nir.add(red.multiply(evi_vars['C1'])).subtract(blue.multiply(evi_vars['C2'])).add(evi_vars['L'])
     evi = numerator.divide(denominator).multiply(evi_vars['G']).rename("EVI").clamp(-1, 1)
     evi2 = numerator.divide(nir.add(evi_vars['L']).add(red.multiply(evi_vars['C']))).multiply(evi_vars['G']).rename("EVI2").clamp(-1, 1)
     return image.addBands([neg_cloud, ndvi, evi, evi2])