1

The GEE tutorial shows how to mask an image for one pixel value using .eq(pixel value).

However, I want to mask all pixels in an image with a value of 15 or less in this dataset

var riverflow = ee.Image('WWF/HydroSHEDS/15ACC');

var flowAccumulation = riverflow.select('b1');

And now I need to use .updateMask. This must be very straightforward right?

2

If you want to keep pixels that have a value of 15 or less than 15 and mask the rest of the pixels:

var riverflow = ee.Image('WWF/HydroSHEDS/15ACC');

var flowAccumulation = riverflow.select('b1');
//Map.addLayer(flowAccumulation)

var masked = flowAccumulation.updateMask(flowAccumulation.lte(15)); 
//Map.addLayer(masked)

On the other hand, If you want to mask the pixels that have a value of 15 or less than 15 and keep the rest of the pixels:

var riverflow = ee.Image('WWF/HydroSHEDS/15ACC');

var flowAccumulation = riverflow.select('b1');
//Map.addLayer(flowAccumulation)

var masked = flowAccumulation.updateMask(flowAccumulation.gte(15)); 
//Map.addLayer(masked)

Hope it helps.

2
  • Just tried this, unfortunately it does the exact opposite. But I did some research and using .gt instead of .lt worked! Not sure what they stand for...
    – Olivier
    Jun 1 '20 at 14:22
  • 1
    "gt" stands for greater than, while "lte" stands for less than equal. In the question you mentioned "mask all pixels in an image with a value of 15 or less". Although the question is different from what you want, I edited the answer.
    – HamiEbra
    Jun 2 '20 at 12:12

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