The Projection-on-fly is a program to align spatial coordinate systems for display and mapping. General audience can use it when printing a map that requires a different look than the original dataset. For the ArcToolbox Project and Transformation, it modifies the spatial coordinate data and creates a new version of the data layer with a different coordinate system. The properties of a layer and changes in the information are irreversible.
In addition, there are some advantages to use remotely sensed Landsat data for geographic analysis. First, it allows the analysts know the relevant changes in the past years. Besides, the analysts can easy to change or combine other geographical coverages in GIS. Also, it is a rapid and convenient tool to retrieve up-to-date information over a large geographical area.
For example, it would be useful to use Landsat for investigating the changes in the coastline of the Wreck Beach from 1975 to 2015. The geographic analysis I am interested in is the coastal process of erosion and deposition which affected the coastal area in Wreck Beach. By considering the time frame in research, I would like to use a 40-year interval in order to examine the geographical changes of the area. A 40-year time interval is chosen due to the coastal processes take time. As a result, a more significant coastline alteration can be investigated and examined from Landsat images. In addition, I set the year 1975 as the starting point because the Landsat data provides a more accuracy and a repository of raster data imaging since 1972.