In Part I, we will explore and obtain publicly available datasets from the Pennsylvania Spatial Data Access (PASDA ) website. We will also review the private data for this lesson and organize the map for analysis.
When working with raster data that you have downloaded, you need to be careful when placing it on your computer. Many raster datasets have an associated Info folder that contains critical reference information. The files contained within this folder are numerically named based on the particular order in which they were originally created. As a result, it is possible that different raster datasets have identically named reference files within this folder.
It is important to note that although these files may have the same name, they do not contain the same information. Therefore, it is possible to corrupt your data if you overwrite one set of a raster dataset’s files with another’s. You can avoid this potential problem by creating new folders for each dataset and extracting each zip file within its own folder.
What are the largest towns within the study area? Where is the study site in relation to the overall area of Pennsylvania?
Raster attribute tables are different from vector attribute tables. Unlike with vector files, each unique value is only listed once.
Do all of the land cover raster datasets have the same number of coded values? How many unique codes does each raster dataset contain? Are any of the codes the same? Do they have the same extent and cell size? Do all of the datasets have the same spatial reference information?