Uploaded on 2015-04-20 by CupidKing

[1]: https://edxuploads.s3.amazonaws.com/1429534488712097.jpg I live in Dalian,China. The photo updated is the urban area that I can reach within miles. From the picture, we can see how many buildings there are in this place. We can see several cars and small crowds. There is a river and buildings still under construction. That is what we can get directly from the photo. What we can't see is how many people resident in this area and how many people come to visit it everyday. These are invisible information. But when night comes and lights turn on ,we can roughly calculate the number of light on and draw a conclusion on the assumption that each family is made up of three people. We can see that there are pines which indicate that the average temperature per year is not high. By knowing how many people dwell in this area, we can make better decisions on traffic planning, which is critical for people's life here. And by knowing the number of people , we can decide whether to build more or slower the development in this area, which does help in city planning.