Remote Sensing - Module 4 - Spatial Enhancement & Multispectral Data Analysis

This week's lab module for Remote Sensing and Photo Interpretation introduced us to a wealth of information related to image enhancements and multispectral data analysis. This involved topics ranging from image enhancements in ERDAS and ArcGIS Pro to interpreting histograms and additional forms of digital data used to identify features. In the final exercise, we were provided criteria that were used to identify three different features. We employed the four main methods we had learned to identify these three features. The four main methods were as follows: 

1. Examine the histogram data for shapes and patterns in the data. 

2. Visually examine the image in grayscale for light and dark shapes and patterns. 

3. Visually examine the image with multispectral band combinations to isolate features of interest.

4. Use the Inquire Cursor to validate the exact brightness value of a feature.

Once we had identified our features according to the specified criteria we used the Create Subset Tool in ERDAS to extract an area around the feature allowing us to then export this subset into ArcGIS Pro to create a map layout. 

The first map below displays water features that were identified by a spike in band/layer 4 pixel values of 12-18. I decided to use the False Color IR as my band combination as it creates a sharp contrast between the water and vegetation.

The criteria for the second feature included a small spike in layers 1-4 around pixel value 200 and a large spike between pixel values 9 and 11 in layers 5 and 6. I looked at layers 1-4 using the panchromatic image to see the brightest areas. I proceeded to do the same for layers 5 and 6 to see what areas appeared darkest since pixel values between 9 and 11 would be very dark. After consulting the histograms and using the Inquire Cursor, I confirmed that the snow and ice features fit the criteria. I chose the False Natural Color as my band combination which displays the snow and ice in a light blue teal color.

The third and final criterion was to locate an example area that shows variations in water using a band combination that makes them stand out. Evidenced by layers 1-3 becoming much brighter than normal, layer 4 becoming somewhat brighter, and layers 5 and 6 remaining the same I identified the areas in the map below using a custom band combination displaying shallow and deep water.