lab6 DEMs in ArcGIS

The area for my map I choose is the range of mountains located in the southwest of Texas, near the Bid Bend National Park. The reason I choose here is the continuous and steep mountain ranges are easily to tell in a topographic map. The extent information of this location is:Top:30.001666666664, Bottom:28.99833333333, Left:-104.0016666667, Right: -102.998333333. The geographic coordinate system used in this map is the GCS North American 1983.

lab5 Projections in ArcGIS

Conformal projection: 

Stereographic projection: the distance from Kabul to Washington D.C is: 9878miles Mercator projection: the distance from Kabul to Washington D.C is: 10112miles





Equidistant projection:

 Two-point equidistant projection: the distance from Kabul to Washington D.C is: 8098miles

 Sinusoidal projection: the distance from Kabul to Washington D.C is: 8098miles

Equal area projection:

Bonne projection: the distance from Kabul to Washington D.C is: 7244miles
Eckert Ⅱ projection:the distance from Kabul to Washington D.C is: 6916miles



Maps were used by people for navigation since a long time. However, after Columbus discovered that the earth is round, people realized that flat maps are not enough and developed Globes. But people use projections on maps again nowadays. Projection of 3D earth on 2D maps is not easy and deformation is also inevitable, because projection can only preserve one property out of distant, area, and shapes & angles. 
Different projections have different functions. Equal area projection preserves the area of earth and can show accurate sizes of landmass. For example, equal area projection is useful in population density and land use, especially in agriculture. Equidistant projection preserves the actual distance from a point or a line, and it is useful for people to calculate distance as we calculate the distance from Washington D.C to Kabul, Afghanistan. The last one, conformal projection, preserves angles and shapes, and is most used for navigation in a local area. 
However, one projection can only offer limited information and distort other properties. If people would like to see the whole earth, they need to combine information from several projections. The most pitfall of projection is that it is country-oriented. For example, in the Mercator projection, Greenland seems like the largest area on the earth, which is really inaccurate and misleading! I guess the reason for the enlarged Greenland area is that the designer of Mercator projection is Flemish, who would like to make his homeland like the center of the world. But maps play an significant role in portraying the world around us, and can easily manipulate our minds. Maybe people in the past used to believe that Europe is the center of world. Another pitfall of projection is that it distorts distance in large scale. When we calculate the distance from Washington D.C to Kabul, Afghanistan, the data varies greatly in different maps. For example, in stereographic projection the distance is 9878miles, while the distance in EckertⅡ projection is only 6919miles. Look at how big the difference is! It is really difficult to complete a large-scale a mission which demands highly precision.

Despite the pitfalls, projection is also really useful in our life as it shows the whole earth on a 2D plane. For example, when people need navigation in a local area, they can use Mercator projection as a guide. And when scientists study the earth structure, they can apply Stereographic projection as a tool. The errors can be minimized if people take some time to choose suitable projections according to their demands. And I hope in the future people can develop better projection to represent the earth and maybe invent a tool to combine all the benefits from each projection.

lab4 Introducing Arcmap

 My first experience with arcmap is really frustrating and disappointed. It pushes me to do much more work than just follow the instructions in the tutorial. I spent nearly six hours to deal with the data of noise pollution, population density, land use, proximity to schools, and I countered lots of difficulties due to the new version of the Arcmap. For an example, some tabs are not in the positons according to the instruction, such as Draw palette is actually not at the bottom of the data frame, so I have to discover them and search the website for help. I even left my USB memory device in the computer lab which contains all my lab work, but fortunately I found it at last.

However, I learned a lot and felt really successful when I finished the lab even it is not perfect. Through   solving the problem of noise of the airport area, I deal with variables such like noise, population, land use, and proximity to schools to solve the problem. First, if the noise expansion is in the school area, it will be reconsidered. And the public also plays an significant role because the airport should be convenient to serve most people. At last the land use is also important as the airport should not influence human activity. I learned the steps of basic GIS: updating, storing, manipulating and presenting the given data. And I found that ArcGIS is much more complex than handmade map. Collecting the data must be more complex and time-consuming than operating the database.

So the pitfall of the ArcGIS is that the program is complex and time-consuming to operate. People need to be carful enough and focus on the detail because a simple inaccurate step or a skipped step may ruin the whole map. Second is that the database for the ArcGIS should be precise enough to offert the accurate information. So it will take a long time to collect data and finish an arcmap. Finally, ArcGIS is still too professional to average people. People without GIS knowledge have difficulty to understand the arcmap and reach the data contained in arcmap, not to mention operate on ArcGIS. They may prefer to easily understood map such as Google maps and MapQuest. 

ArcGIS still have some advantages unattained by other programs. The biggest advantage is the convenient manipulation over data. ArcGIS offers an opportunity to put different data together, make them related and let us to operate them at the same time in one program. Second is that ArcGIS is costumed to satisfy different purposes because people can just download the database and hide the database according to their preferences and intentions. For example, if I would like to know the relationship between the population density and airport are, I can realize it by simply checking the box for population density data frame and closing other database to make my own thematic map. Third is that the database for ArcGIS is obtained carefully and more reliable than that of neogeographic maps.

ArcGIS now is under the control of government to protect the data accuracy, but I hope one day it can be accessible to ordinary people. In this way, the modernization will speed as people can obtain information more easily. And I hope ArcGIS can offer dynamic maps one day by updating the data

 automatically. ArcGIS is still on its way to provide a better view of the world.