Clouds covered the bigemap map.

There are many reasons that affect the image definition of satellite maps, such as the weather. For example, in the following Google Earth History image, the image is blurred and covered by clouds. Because of this, the general presentation of satellite maps is filtered, because satellite map shooting often leads to unclear shooting because of the dark weather and sky.

Geographical location is also a reason that affects the clarity of satellite maps. Coastal cities often have sea breeze and little dust. For example, Japan is an island country, with the East Sea of China in the east and the Yellow Sea in the west. It is humid all the year round, with abundant precipitation. Not only is the vegetation coverage high, but also the sea breeze blowing from coastal cities rarely sees dust. Therefore, in the historical images in satellite maps, we usually see satellite maps with relatively high quality. So I continued to compare the imperfect satellite maps taken in historical images to see the gap in perception.