Calculating vegetation indices NDRE AND RECI using Sentinel 2

Question

I am trying to calculate NDRE and RECI using Sentinel imagery ON ArcGIS software . For RECI( RED EDGE CHLOROPHYLL INDEX) the formula is (NIR/RED-1). Can you tell me which band to use in order to calculate this, like for NIR do I have to use band 8 or 8A and for red band which band do I have to use band 4 which is red band or 5,6,7 which are red edge band?

When I use formula as float(band8/band5 -1) my result appears completely black.

And for NDRE (Normalized difference red edge index) I was calculating it like float(nir - red edge)/float (nir + red edge) I was using band 8 as nir and band 5 as red edge.

Do I have to use band 8A instead of band 8 for this and if I am using band 5 correctly for red edge or do I have to use some other band instead of band 5?

Answer 1

In this arcgis.com link, it defines NDRE (a.k.a. VRE Raw) as:

NIR(Band08) - VegetationRedEdge(Band05) / NIR(Band08) + VegetationRedEdge(Band05)

So your use of Band 5 is correct.