Week 8 Lab

Week 7 Lab

 3D Rendering

 Aspect Map

 Shaded relief map

Slope map

The area I selected is the border between California and Nevada in the Sierra’s. This area includes Lake Tahoe and some of the immediately surrounding mountain ranges. The coordinates for the extent of 39.5319444439 degrees North at the top and 38.576666666 degrees at the bottom most extent. From east to west the map ranges from -119.5675 degrees to -120.421111111 degrees. The geographic coordinate system used was GCS North American 1983.

Week 6 Lab

Map projection plays a very significant role in geospatial information systems. Being as the world is generally shaped like a sphere, excluding protrusions and its slightly ellipsoidal shape, projecting the 3D world onto a 2D map can be a difficult process. As there is no way to flatten the Earth onto a map without distortion, there are no map projections that preserve distance, area and direction. We must rely on many different map projections to be used for their specific purposes. In the following paragraphs I will discuss the three factors that projections are created around.

                The first type of map discussed is a conformal map. Conformal maps preserve angles.  Conformal maps are great for navigation as they will not distort the angle (direction) in which one is trying to go. Many conformal maps however do no preserve distance and area. The first conformal map projection I used for the project was the Mercator. In this projection I found the distance from Washington DC to Kabul Afghanistan to be 10112 miles. In actuality this distance is 6930 miles. Likewise the Gall Stereographic projection, which is also conformal, read a distance of 7109 miles between the two points. Despite giving completely different distances, these are still accurate and useful maps just not for the purpose of measuring distance.

                The second type of map discussed is equal area. Equal area maps as the name suggests preserve the area of features on maps. These maps are useful for many statistics such as population per square mile or the size of a country. I used a Mollweide map projection to get the distance from Washington DC to Kabul Afghanistan and got 7870 miles between the two points. Likewise with the Sinusoidal projection I received a distance of 8098 miles. Neither of these are correct as they are not made for measuring distance.

                The third type of map projection is equidistance. As the name would suggest this preserves the distance between two features. These maps are great for finding the length of a trip or calculating the length of a flight and the fuel needed for the plane. For these I used the equidistant conic map projection and the equidistant cylindrical map projection. The equidistant conic map gave me a distance of 6964 miles between the two cities. This is very close to the actual distance, if not spot on. The equidistant cylindrical map projection on the other hand baffled me as it gave me a distance of 5067 miles. I am not sure if this is not an equidistant map as would be suggested by its name or if there was an error somewhere.

Thanks,

-Vinnie

Week 4 Cont.

ooops almost forgot this:

                ArcMap has a lot of potential. It is a highly powerful software program that not only allows you to create maps, but also analyze the data that is displayed on other maps. In the next few paragraphs I will explore some of the potentials and pitfalls of ArcMap. In the first exercise we were taught that one reason ArcMap is better than a regular map is because you can zoom in to see detail on ArcMap however on a physical map you are bound to the detail allowed by the scale of the map. ArcMap is also powerful because people can add script and images to maps.

                In exercise two I learned that ArcMap lets you switch between and work within multiple data frames so that multiple maps can be produced and compared in the same file. The placement and other properties of the map can be highly stylized to the users liking or needs. This level of stylization also allows for the ArcMap software to categorize certain data on a map by color or style. Another nice feature of ArcMap is the ability to turn off and on layers so that one only has to view the features necessary to their interest. Additionally other non-spatial information can also be attached to features and displayed in graphs or tables. The tables can be joined or even have a feature added to them.

                Another nice feature of ArcMap is its ability to calculate attribute values and due many calculations in a fraction of the time that it would take by hand. Other cool features of ArcMap are the snap tool and the parallel tool which make drawing and joining lines easy and precise. Digitization in ArcMap is far more accurate than can be duplicated by hand. Digitization of other features is also made easier by the ArcMap’s ability to compute boundaries.

                There are a few potential downfalls to ArcMap however. One such downfall is a failure to save properly. Unlike a physical map, an electronic map can cease to exist with the mis-click of a button. Another potential pitfall of ArcMap is building a reliance on the power of the program and thus losing one’s ability to compute data for themselves. Additionally it is easy to note that if one is not familiar with the ArcMap software it is hard to pick up by one’s self. Another potential pitfall is that data can confused if not properly stylized on a map. For example using very similar colors to display different dat can be confusing to someone reading the map.

Week 4 lab