AT 309 Lab 3: Introduction of Remote Sensing

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Introduction


Ever since history has started being documented, humans have been obsessed with looking at things at a birds-eye view. Maps give us exactly that without requiring the hardware to do so. For the select few that have the hardware, there are different applications with this type of data: orthomosiacs, geospatial data, counterintelligence, remote sensing to name a few. Focusing our attention on the gist of the lab, Remote Sensing is the process of analyzing an object, area, or phenomenon through acquired data using a that is not intertwined with the subject being analyzed. A lot of the technology being used is satellites and more recently UAS. The use of UAS within the Remote Sensing industry relates to a much smaller application. There are lots of software that make accessing these types of data easier, such as ArcGIS Earth. This software enables users to access a wide library of online data sets and have tools relating to elevation.

Methods

For the purpose of this lab, ArcGIS Earth was used to dive into remote sensing and how to use software relating to it. Through ArcGIS Earth, students were tasked with exploring the different features offered by this software and see examples of all the types of data it has to offer. The data that was observed was then used to bridge into what it means in terms of UAS planning and how each of the tools that were used is useful for the planning process.

Discussion

For the lab, it was broken down into various parts/steps that we were tasked to do. Within those steps, we explored the various tools that ArcGIS Earth is equipped with. The first step was exploring basemaps and the types of data that we could explore. Figure 1 shows a basic terrain with labels map.

Figure 1: Above West Lafayette and Lafayette, IN are pictured within the terrain with labels map data set.
Next, one of the various tools available is explored within the next step. We used an elevation profile line, which plots out the levels of elevation across a generated line. This allows for UAS operators to get an idea of the elevation upon a certain path. Figure 2 shows a profile line between West Lafayette and Lafayette.

Figure 2: On the map, it shows the profile line between West Lafayette and Lafayette, while the graph right below graphs the elevation of the line.
The next tool that was used was line of sight. The purpose of this tool is to plot out can be seen and what will obstruct the view from a certain point if trying to see a different point. This would be useful for UAS planning because it would give a pilot an idea of what could potentially be obstructing a certain view point when trying to fly visually. Figure 3 shows an example of a line of sight.

Figure 3: Above the image shows what can be seen between the two points. The blue color is an example of what can be seen, while the pink shows what cannot be.
Viewshed is similar to line of sight, but it shows a wider range rather than one singular line. this would be especially useful since it gives a general direction of view, and it allows for pilots to see what will obstruct view close by. Figure 4 shows an example of viewshed.

Figure 4: Above shows a viewshed of 360 degrees and shares the same model of blue being visible and pink showing obstructions.
With the basic tools cleared out of the way, we then explored the different data sets that can be downloaded online for analyzing. Using different data sets give more information on the landscape and can also be acquired through UAS as well. Figure 5 shows the USA NAIP Normalized Difference Vegetation Index (NDVI), and it gives information on the health of plants.

Figure 5: This data set shows the NDVI data of the West Lafayette region. If an area is a deeper green, it means that the vegetation is healthy, while a red or close to shows either inanimate or unhealthy plants.
The next data set is the USA NAIP Color Infrared set, which shows the same type of data as the NDVI set, but it instead shows healthy vegetation as red and bareground or urban areas are a light blue color. Figure 6 shows an image of it.

Figure 6: Above shows the same area of West Lafayette, which shows lots of urban area surrounded by vegetation.
For the last part, we got to look at data sets acquired by UAS. An orthomosaic was needed to created these data sets since UAS is a smaller application, and it lacks in stability unlike satellites. Figure 7 shows the standard RGB data set. The only issue is that the data set needs to be viewed at a certain viewpoint, otherwise it does not display. The main reason for this is to see it from the same angle as it was obtained to ensure accuracy.

Figure 7: Above is a field near West Lafayette that was studied.
Again, the angle at which it was taken might make it slightly difficult to analyze since there is not a top-down view, but it does it's job nevertheless. Figure 8 shows the same field but in infrared.

Figure 8: This is the same field, but it had to viewed at a higher zoom percentage otherwise it would not display.

Conclusion

As displayed above, the use of UAS for remote sensing is limited and only works for certain instances, but it serves its purpose and does so effectively. The use of ArcGIS Earth proved to show how important and powerful GIS data can be and shows analyzing it is not difficult. In terms of UAS planning, ArcGIS Earth would also be useful since it gives the crew access to view a potential working site and can see the different characteristics of such area. Once the data is collected, it allows for the crew to map out their data to make the analysis process easier.

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