Hi Ingo,
Rather than adding the individual bands, can you add the entire multispectral raster to the Map and select it in the Contents pane? That will enable the Indices drop-down.
From where you are now, you can use the NDVI raster function as well. The function gives you a little more control over which specific bands to use in the NDVI analysis, so it might be a good idea to start here:
- Drop down the Raster Functions menu in the Analysis section of the Imagery Ribbon and Select Raster Functions.
- Once the Raster Functions pane opens, search for NDVI and select the NDVI function that's returned (if you'd like a colorized output, select the Colorized NDVI rather than just the plain old NDVI)
- For the Raster, click the little plus sign next to the parameter and navigate to your imagery file. Select the whole file, not an individual band.
- Enter the relevant bands (3 and 4) for the Visible Band ID and Infrared Band ID
- Click the Create New Layer button at the bottom of the pane and select "Create New Layer." We should see an NDVI layer get added to the Contents pane. Keep in mind that this layer is just in-memory and if you want to save it permanently, it should be exported (right-click on the layer, select Data, then Export Raster)
If you'd like to read some of the documentation on the NDVI raster function and raster functions in general in ArcGIS Pro, here's some of the relevant ones:
NDVI function—ArcGIS Pro | ArcGIS Desktop
Raster functions—ArcGIS Pro | ArcGIS Desktop
Raster Functions pane—ArcGIS Pro | ArcGIS Desktop
Hopefully that helps!
-Lauren
As you can see, the two images are shown on the left.