Fixing Misaligned and Improperly Referenced Spatial Data, and Advantages to Using Landsat Data
How to Fix Misaligned and Improperly Referenced Spatial Data: Step-By-Step Guide
1. Launch ArcCatalog and preview your data information for each layer. This can be done by right clicking on each of the layers, go to Properties, then to the XY Coordinate System tab. The coordinate system will indicate “unknown” if Spatial Data is missing. Refer to and take note of spatial data of the other layers that are not missing spatial data to assure the same datasets are used later on.
2. When the layer is added to the Table of Contents (by clicking on the add data button at the top of the toolbar), a warning will pop up to state that the spatial reference is missing and the layer will not appear visible on the map. If this occurs, remove layer from Table of Contents.
3. In the Catalog tab, launch Properties of the layer. Under the XY Coordinate System Tab, click on Geographic Coordinate Systems and find the same systems as the other layers.
4. Add layer that was missing spatial data back to the Table of Contents. The layer should be visible as everything should line up.
5. To do a specific analysis on the data provided, it is possible to project layers with different coordinate systems to be on the same coordinate system. The coordinate system depends on what type of analysis is being conducted. To create a new version of the data with a different coordinate system, launch ArcToolbox. Navigate over to Data Management Tools and find Projections and Transformations, then click on Project. To modify data, change Output Dataset and Output Coordinate System to match the coordinate systems of the other layers. Click Ok and operations will be completed. Add new layer to the map.
Advantages to using remotely sensed Landsat data for geographical analysis:
Remotely sensed Landsat data enables geographers to examine land changes over a long period of time by collecting data using a satellite that detects reflected solar radiation in which a visual image of the area is created. The satellite is continuously orbiting around the world collecting data, but an image of a singular spot is collected on a 16-day cycle. The information collected is important for geographical analysis because it allows geographers to view the land changes over time, from minute to large scale differences. Landsat is also able to detect near-infrared, mid-infrared, and thermal-infrared light that the human eyes cannot perceive. Examples of what Landsat data is useful for include monitoring water quality, glacier recession, invasive species, coral reef health, deforestation and population growth. A huge advantage to Landsat data is that during time of natural disasters, Landsat can provide data for areas that are too dangerous to survey by land. Landsat can help assess damage from natural disasters, such as fires, floods, tsunamis, hurricanes, and volcanic eruptions.