Fixing Misaligned Data
Often when we download or receive data, it doesn’t match or line up with the data that we already have. One common problem is when the coordinate systems are misaligned and improperly referenced, this can lead to distorted distances, areas, shapes or angles.
Depending on the project, we can fix this in one of two ways, either ‘projecting on the fly’, or by using commands that actually changes the coordinates. ‘Projecting on the fly’ is used when we are simply trying to make the map more visually appealing, there is no actual change to the coordinates. In contrast, using the commands in ArcToolbox allows us to change the coordinates so that in depth analysis can be performed.
Landsat Imaging
Landsat, a type of remote sensing, is used to gather information about an object or surface from a distance. Landsat remote sensing uses solar energy powered satellites that scan the earth’s surface to measure changes and responses to the surface, current technologies allow for a new picture every sixteen days.
This is useful to geographic analysis because we can compare before and after photos to see how the landscape changes. A great example of this is using Landsat imagery to compare before and after photos of the Mt. St. Helens eruption, we can clearly see how the landscape changed from 1979 to today.