Introduction

Social media is currently the most efficient channel to spread a news or organize a campaign.

For example in the paris terrorist attack on the evening of 13 November 2015, a twitter hashtag #PorteOuverte was created by a “hero” called Sylvain Lapoix, and quickly spread around Paris to helped frightened people on the nearby street to find a safe shelter.

Although we know that hashtag is now very popular around the world, we don’t know how such popular hashtag topics growing from a single original poster in a small region and finally with thousands or millions of responses spreading throughout the world.

In this project we are focusing on visualization of the spreading of popular Instagrams based on specific hashtag by using D3. We will visualize the spreading of hashtags from four perspective.

First, we will visualize the geographical spreading of popular hashtag from the Aerial View or "God View" as shown in the map below. At first, someone posted the fisrt uniquie hashtag in some loaction. A light point will be shown on the corresponding loaction on the map. As time passed, more people will post other instagrams with the same hashtag in other locations, therefore more light points will be shown on the map. The lumination of the light points corresponded to the number of instagrams in the specific loaction, the more hastags posted, the brighter the light. Finally, such hashtag become popular and we light up the world.

Second, we will visualize the increasing magnitude of hashtags as shown in the line chart below. We will show you how a hashtag become popular with number of hashtags posted over time from the original time.

Third, we will visualize the dynamic change of the instagram contents with the same hashtag as shown in the photo wall grapgh below. We will also show the top 20 representive hashtags over time to inform the viewers of the changing hashtag contents.

At last, we will visulaize geographical influence of the hashtag. Using a stacked bar chart, we will show you that with time growing, whether the hashtag is more popular in a small region or a global hot trend.