Mod 4: Spatial Enhancement, Multispectral Data, and Band Indices
This week covered a ton of material which included spatial enhancement, multispectral data, and bands. First, we took a trip over to Glovis to download some satellite imagery to begin this week's map. Then I used the tools I discovered in the lab exercise to make the below three maps manipulating the image in ERDAS and creating the final map in ARCGIS.
In ERDAS Imagine I used the histogram tool and inquire cursor to identify the various spikes I was looking for in the three features. I started with creating a map with False Color Infrared to identify a feature that had a spike in pixel values between 12 and 18. The feature I was able to find was identified as the water on the map but I chose the deep body of water located in the Puget Sound on the image because of the deep black in contrast to the red most other things showed up as (Map1_FalseIR). By using False Color IR the water bodies were clearly distinguishable in contrast from land and other features on the map. For the second feature, I identified the ice/snow-capped mountains by using the histogram and inquire cursor in ERDAS Imagine identifying small spikes in layers 1-4 at pixel value 200 and a big spike in layers 5-6 at pixel value 9-11 (Map2_FalseNat). To see this contrast I chose False Natural Color because it clearly showed the difference between the land in bright green to the snow/ice-capped mountains in bright blue. Then finally the third feature I was looking for was an area in the water where layer 4 was slightly brighter but 5-6 were unchanged (Map3_True). The example area I chose was a runoff area near my initial point found with the False Color IR. I did initially discover the area with the False Color IR but chose to showcase the feature with TrueColor because even with the True Color you can clearly see the sediment and nutrient runoff in contrast to the rest of the water and surrounding land mass. I also chose this display of the feature because these are the types of maps I am familiar with when I’m researching environmental subjects. Typically when we present a map we try to produce a real-life image of what is happening in the estuary or bays which is typically more relatable to the public.
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