Abstract
Arc-GIS pro is a very powerful GIS mapping software. Using Arc GIS you can import collected data from flown missions to create detailed maps of the data collection. In addition using ARC-GIS allows you to evaluate a map using different data layers with each layer being that of different color bands. With the nature of the data being evaluated in this lab being that of a controlled burn, being able to investigate the relationship between certain color bands to how data is visually displayed allows for connections to be made between properties of the color bands and what certain band combination display in terms of information being represented.
Methods
With data already collected before this lab we where not required to conduct any outside data collection before beginning the lab. The data given to us surveyed controlled burn areas within Purdue Wildlife Association. First by examining the data by selecting each band layer such as that of red edge I was able to identify the properties of that band . Next I would turn that band off and turn on the blue band and see how the visual being presented changed based on the new color band being activated. With color bands it is important to understand there reflectance values and in terms of the color ramp and how the color ramp establishes a range of values that are indicative of each band. Towards the end of the lab instead of focusing on the effect of individual color bands the focus shifted to understanding color band combinations specifically the color band combinations that produce false IR images.
Discussion and Figures
Throughout this lab there where many key questions that I was tasked with thinking critically about. One such questions has to do with the importance of looking over data for its properties before getting into the nitty gritty with remote sensing. The main reason it is important to carefully look over your data is to make sure that everything is formatted correctly especially making sure all units being used are correctly selected. One such example of this is when surveying a mine it is important to account for the change in possible elevation values. When examining data that was processed throughout the lab some key observations that I made where how there is a relationship with the NDVI shows reflectance values of burned areas in orange while everything else that would normally be shown in the RGB color bands was then reflected in more of a light purple.
Red | Band 1 |
Green | Band 2 |
Blue | Band 3 |
Figure 1: Band assignments for normal RGB layers.
Red | Band 5 |
Green | Band 3 |
Blue | Band 2 |
Figure 2: False color IR band assignments.
Figure 3: This image uses the band assignments as referenced in figure 2 creating a false IR image.
When examining figure 3 and how the band assignments from figure 2 effect the overall image being displayed what sticks out is how it is displayed as a false color IR. What this means is that when looking at areas of say healthy vegetation, those areas would normally be shown is green but are instead being displayed by the purple/pink color which is not the real color of those areas.
Figure 4: Post burn using NDVI.
Something that is different when using the NDVI is that areas that are burned are now being displayed in the bright orange compared to the composite RGB which is normally displayed in purple. Furthermore it is important to analyze the density/brightness of the orange of the burn areas as when the color is more bright/dense is a good indicator of the extent of the burn itself.
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