DEM's: Making Maps from Elevation Data!

This week was my favorite project because for the first time we got to work with 3D modeling using elevation/topographic data--also known as DEMs (Digital Elevation Models). I chose to use data from the San Francisco Bay Area because as a Northern California native I know how interesting the terrain is due to the large amounts of geologic activity there. At first using/making DEM's seemed like a daunting task, but the most difficult part of the entire lab was simply downloading the information from the USGS website. ArcMap/ArcScene were very user friendly and allowed for a lot of creative expression by being able to change the different elevation color schemes and backgrounds for the map. I used ArcMap to create several maps including the Shaded relief model which displays various elevation areas using a scale of light to dark purples. The slope model shows that there is a steep slope in the area as almost the entire map is colored in with the magenta representing the steepest grade of slope. The aspect model demonstrates which direction areas of the map are facing and shades them a certain color (indicated by the legend). Finally, the 3D model demonstrates how the area would look if one were looking in reality from a birds eye perspective. Below I've included the Raster Download Information which includes the decimal and geographic coordinates of the area in the Bay I mapped.

Raster Download Information for this portion of the San Francisco Bay Area:

Number of columns: 3707

Number of rows: 6427

Resolution in x direction: 0.000277777777796473 Degree

Resolution in y direction: 0.000277777777796473 Degree

Coordinate system ID Native: 4269

Top edge Native: 38.5024999993735 Degree

Bottom edge Native: 36.7172222214756 Degree

Left edge Native: -123.098611111054 Degree

Right edge Native: -122.068888888763 Degree

Coordinate system ID WGS84: 4326

Top edge WGS84: 38.5024999993735 Degree

Bottom edge WGS84: 36.7172222214756 Degree

Left edge WGS84: -123.098611111054 Degree

Right edge WGS84: -122.068888888763 Degree

The final product--the 3D model:

The Original image produced when ArcMap processed the Raster Data:

Map Projections

Map projections are essential when creating a two dimensional interpretation of our three dimensional world. Map projections are significant because of their ability to represent the earth on a flat surface--a huge convenience for map users. Without projections, we would be forced to refer to globes when wanting to view a representation of the earth. Imagine having to carry around a globe on a hike or while driving in your car while looking for directions!?!

Some caveats to creating projections is that no projection can preserve real life distances, shape, area and right triangles exactly as they appear in reality/on a three dimensional surface simultaneously. Moreover, an unskilled or unaware map user may not be aware of the built in biases of projections. The mercator projection is infamous for creating misleading perceptions of continent size and area amongst users. Yet, it is still one of the most popular ways of displaying the earth and can be found in various classrooms/textbooks!


Projections can, however, be manipulated to show one of these features extensively. Therefore, different projections are more appropriate for certain contexts. For example, the mercator projection featured above is meant for Nautical navigation. Meanwhile, the conformal conic projection (also represented in the diagram above) is better suited towards aeronautic navigation because it presents circles as straight lines.

Finally, new and improved electronic technologies oriented towards the field of map projections and cartography specifically should allow for more accurate and varied cartographic representations of the earth. These same technologies also allow projections to be incorporated further in our daily lives and allow more 'average joes' to be able to create and use their own maps. This, however, has several consequences as most people are still very unaware of which projection is appropriate for which context. As previously stated, a projection used in the wrong context can provide wrong and/or misleading information.

Arc GIS Tutorial

Exploring GIS: Potentials and Pitfalls

Over the past two weeks I had the wonderful (and honestly draining) opportunity to explore the ArcGIS tutorial. The tutorial aims to instruct and introduce the essential aspects of ArcGIS software. The tutorial is divided into cumulative sections in order to present a chance for students to repeat some skills and to reach a point where they can operate the software independently. During this short period of exploration I discovered that there are several potentials and pitfalls to using ArcGIS.

Potentials:

When one begins to use the ArcGIS tutorial one realizes exactly why this software is worth approximately 10,000 dollars a bundle. The software is clearly capable of performing a variety of analytical functions. While it displays maps and allows for cartographic manipulation based on data layering, it can also perform general statistical analysis. For example, in the ArcGIS tutorial one can create graphs, charts, tables based on data sets and layers. Not only does ArcGIS have a lot of built in capabilities, it can also serve a variety of purposes and uses in many different fields including: city planning (as demonstrated by the tutorial), tax purposes, business marketing, emergency planning, interpreting census data, political science and so much more!!!

Moreover, the software is surprisingly relatively simple and easy to use. I am not the most technologically inclined individual and the software was easy to explore through the tutorial. My real frustrations came from a lack of knowledge about windows operating systems in general rather than the program itself. In fact, by stage five of the tutorial I caught myself having fun playing with the borders, shading and coloring of my project.

Pitfalls:

While ArcGIS is an incredible software with a lot of capabilities it was certainly not without its own downfalls. The software can become easily overwhelmed and experience freezing/slow down and sometimes crash. Thus it is imperative to press save after every stage completed. Unfortunately, I learned this the hard way when at the end of stage five the program experienced a 'fatal error' and decided to reboot without recovering my progress. While this issue is easily avoided if one repeatedly remembers to save ones work, it would probably get frustrating if I was researching a big project and had to fear that I could lose all my progress at any given stage.

Another grave pitfall for this software is being available only to PC users and not to other platforms like Mac and Linux. Mac and Linux are better known for their graphic capabilities and for their ability to multi task--two features that are essential for running ArcGIS. In addition, more college students are beginning to use macs and this is the prime age group for learning geo-spatial technologies.

Finally, one of the gravest pitfalls of ArcGIS is its price. This software has the proven capability of having so many functions. It can give anyone who knows how to use it the power to learn more about the surrounding world and to make changes politically, economically and for our own personal safety. Yet, at a price of 10,000 dollars a bundle this software quickly becomes unaccessible to the average individual and only truly available to college students fortunate enough to be at a University with a Geography program, rich professionals and to politicians and some planning/emergency services organizations.

Despite my complaints ArcGIS is an amazing software and here is my finished product as a result of the tutorial: