Cloudless satellite image

I found excellent Image-compositing scripts for filtering weather out of satellite images https://github.com/celoyd/wheather and decided to give a try.

This analysis based on MODIS subsets image from NASA - https://lance-modis.eosdis.nasa.gov. See below:

Located directly on the Equator and covered with mountains and rainforest, Indonesia is one of the cloudiest places on Earth. Getting cloud free image from MODIS is difficult

Sample quick look, 23 July 2012

Following the script, I downloaded the MODIS quick look. And you can see every day sometimes cloud-free and mostly not.

1 - 31 July 2012, 1km pix res

If we could create an average image from all the collection in the previous picture, it will look as below picture.

Simple average

Then we can sort per pixel of all the image collection, and leave the least cloudy-looking layers and average the rest. Details are below:

• Split them into strips

• Sort the strips, pixelwise, to remove cloud cover

• Average the cloudless strips

• Rejoin the strips into a cloudless image.

Finally choose the top of quality and we got below picture.