[GIS] How to combine bands and band ratios using earth engine

Question

I am trying to display a multispectral image of bands (4,5,6,4/6,6/5) using Landsat8 satellite imagery. I am doing this in Google Earth Engine using Python. I am new to earth engine and python, so I am taking this as an important learning exercise.

For example, I would like something as intuitive as the following to work (where "test" is an image from Landsat8):

Image(url=test.getThumbUrl({
         'region':safata_region,
         'bands':'B4,B5,B6,B4/B6,B6/B5'
        }))

But it doesn't (If I were to remove the ratios B4/B6 and B6/B5 it works)

Creating the ratios of bands 4,5, and 6 is simple. For example:

A = test.expression(
'RED/SWIR',{
    'RED' : test.select('B4'),        
    'SWIR' : test.select('B6')
    }
)

B = test.expression(
'SWIR/NIR',{
    'NIR' : test.select('B5'),        
    'SWIR' : test.select('B6')
    }
)

But I cannot combine this with the other bands in the same fashion as above because A and B are not bands of "test"… I tried finding something similar in Google's fantastic guides, but no luck… Anyone able to give some guidance?

Answer 1

You need to add the bands to your image using, for instance, addBands.

var combined = test
               .addBands(A.rename('B4B6'))
               .addBands(B.rename('B5B6'));