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The Difference of Filtering Clouds and Masking Cloud in Google Earth Engine
Cloud is one of the main barriers for scientists who want to analyze the object on the earth’s surface. Cloud strongly limits the ability of optical usefulness of satellite imagery, unless the intention is specifically directed to analyze clouds themselves. Cloud may establish noise in the image statistic analysis due to its stretched ranges instead of focusing on the pixel value range. Basically, it increases the radiometric distortion of land surfaces. Aside from that, masking feature is also necessary to remove dark pixels due to the effect of cloud shadow.
My previous article discussed how to filter cloud from certain area of interest. There are two ways to minimize the effect of clouds on the image, by filtering the image or masking the image. Here is the difference:
- Filtering the cloud
Filtering the cloud means that we create our script to choose the date that has the least cloud cover within a specific time range. We can establish the threshold of cloud cover that we want inside the code.
2. Masking the cloud
Masking cloud is used with the multi-temporal satellite. There are several methods to mask the cloud. The underlying concept of masking cloud is equalizing pixel value of cloud into zero ‘0’
The area chosen in this exercise is Palu, Indonesia. You may choose your own area of interest.
