Establish an Air Quality Monitoring Map on the Web with SuperGIS Server API
As a known fact, the air is an essential element for all kind of organisms. But in this modern world full of chimneys from factories, it is often hard to find clean and quality air that we can take a deep breath and relax. Located at urban areas, huge factories and power plants usually emit exhaust gas contain complex chemical compounds or micro particulates, which might cause chronic diseases for the respiratory system. In the developing countries such as China and India, the problem is particularly critical. Beijing, the capital of China, is a mega city famous for its fast development while is also notorious for serious air pollution. The problem is so severe that the residents of Beijing sometimes can’t even see the front entrance of the Forbidden City clearly while standing on the Tiananmen Square. On the other hand, citizens of developed countries such as the United States, the UK and Italy are also sometimes disturbed by the bad air quality despite more comprehensive environmental regulations and legal enforcement.
As mentioned above, the air quality is essential information for modern people, which might hugely influence our daily decisions. To gain an overall understanding of air quality and the distribution of pollutant emission sources, some of the environmental protection departments or weather forecasting institutions try to create online map services that reveal such information for citizens. But the monitoring stations or emission sources are often too many and lead to a slow-speed service, so users must wait a long time for getting the information. And also, the default visualization effects of GIS server software are generally not fancy enough for the citizens to use.
To create an air quality online map service that people are willing to use, two goals must be accomplished.
First, the map service should be fast enough, so users can pan the map view and adjust the scale of the map easily.
Second, the online map service should be able to create or integrate visualization that is attractive enough.
As one of the most developed countries in the world, the government of the US has released comprehensive data in almost all fields. The Environmental Protection Agency of the US has integrated resources across different departments to establish a platform for monitoring emission sources. We can find the sources that emit CO, Pb, NOx, VOCs, SO2 and PM on this website and can be downloaded or connected with ease. In this case, we will use SuperGIS server to establish an online map with these data.
▲ Fig.1 The Air Emission Sources Website built by EPA
To create an online map, the APIs of FeatureLayer and CSVLayer should be used first for adding feature services from SuperGIS Server and online CSV files from the air emission platform respectively. After setting the features and CSV files properly, users should use symbols and the renderer to design the map as they want.
In the demonstration map we built, we classified the emissions sources into several groups and displayed them in different colors and sizes by its emission amount with ClassBreakRenderer. And for solving the speed issue of online maps, ScaleDependentRenderer is used to present different layers only at specific scales, so the performance of online map will not effect by massive data amounts.
▲ Fig.2 The Online Map in Small Scale
▲ Fig.3 The Online Map in Large Scale
Last but not least, Chart.js is included to our SuperGIS Server API for creating a chart that can show the total emission of a specific state and federal average, which make the map service more informative and attractive.
By following the steps mentioned above, an online map for monitoring air quality was successfully established. This map has achieved the goals that we set previously. The map service is speed up, and the map display can be customized with other visualization effects. By applying the ScaleDependentRenderer, the data will not all be displayed simultaneously but at specific scales, which make our air quality online map fast-responsive. And the ClassBreakRenderer is used to make the data displayed in different sizes and colors, letting users understand the information of map effectively. The extra visualization effect from Chart.js is also integrated to make our online map more informative and attractive.
Anyone who wants to build an online map should consider using a GIS server with various APIs such as SuperGIS Server, which can help users to adjust and manipulate the map as they want. Institutions that have such demand are recommended to select SuperGIS Server to build their online geospatial platform, as Supergeo is a team that has long-term experience in cooperating with various enterprises and public sectors.