AT 309 Week 3: Intro to ArcGIS Earth

Introduction

 In week 3, the class moved into more hands-on projects. We were introduced to ArcGIS Earth, an ESRI software that allows users to analyze maps projected on a globe similar to Google Earth. While Google Earth is mainly used as a globe to look at various locations around Earth, ArcGIS Earth provides users with many tools that allow them to manipulate and analyze data. The tools can be used to analyze data already recorded from UAS missions, but they can also be helpful in mission planning before users go out to fly. GIS software utilize geographic information to create 2D and 3D maps for analysis. These GIS software are very important in the UAS industry as UAS are widely used to capture geographic information. UAS may be used to capture this data, but the data is useless if users do not have software that can create maps and models using the data captured. This is where GIS software come in.

Navigation

 Navigating around the globe in ArcGIS Earth is fairly simple. Listed below are some of the basic controls that users have access to to better navigate and get the desired orientation when looking at their map.

Zoom - Using the scroll wheel on your mouse will zoom in and out of the map.

Pan - Holding the left mouse button while dragging the mouse allows you to pan around the map and put the focus area in the center of the map.

Tilt and Rotate - Holding the right mouse button while moving the cursor can tilt or rotate the map about the center of the image. This makes it easy to orient the map or 3D model to different view points such as a top-down view or a bird's eye view.

Navigation Tools - There are two tools that may be helpful for quick navigation: the Home button and the Compass button. The home button zooms out until the projection is entirely in view and pointing North. The compass button rotates the map to where North is pointing up.

Tools

The toolbar is located in the top left of ArcGIS Earth. A brief summary of some of the tools that are useful in UAS projects is listed below.

Add Data - The 'Add Data' section is where users add map layers. There are many selections in the 'ArcGIS Online' section that include satellite data around the world. The maps located here vary between terrain maps, true color maps, and false color maps. UAS are used to capture many different types of data. This data could could be a simple map of the area or it could be a false color map looking at vegetation. The 'ArcGIS Online' section provides users with different examples of data which could be useful to someone that needs practice analyzing these types of data. Additionally, the 'Expand Table of Contents' tool allows users to quickly apply or remove the layers that they added to their map.

Interactive Analysis - This section has 3 tools that may be very useful to UAS teams in mission planning: Elevation Profile, Line of Sight, and Viewshed. 

Elevation Profile - This tool allows users to draw a line on the map and see the elevation changes along the line. 

Elevation Profile Tool used to observe the elevation change in a canyon.

The photo above is a screenshot of the 'Elevation Profile' tool in use. The blue line is the path I wanted to analyze. This area is a canyon near Death Valley, where there should be a noticeable elevation change.  

Elevation Profile Graph exported from ArcGIS Earth.

When exporting the map through ArcGIS, the elevation profile graph disappears. This is not a problem as there is an option to export the graph separately. The graph above is the graph that was generated for the elevation profile shown above. This tool is very helpful in mission planning as UAS teams need to know elevation changes in order to make accurate flight plans. When looking at the base map, without Elevation Profile, there is information at the bottom that includes elevation but this tool is more useful as it gives users an easily interpreted graph of the elevation changes along the line. Users could decide the path of the flight plan and then replicate the lines between waypoints with 'Elevation Profile' and use the provided graph to determine an appropriate elevation for the waypoints. Using tools like this to assist in mission planning will make the flight plan safer as users can make sure the flight plan will not lead the UAS into obstacles that could cause damage.

Line of Sight - Line of Sight is a tool that allows users to plot points with lines extending from them that show how far the line of sight extends before an obstacle blocks their view. 

Line of Sight tool applied to a canyon.

This tool could be used to check visibility from a point on the ground or from a camera at the desired elevation. This is useful in mission planning because it could show the visibility from the ground control point. Users could even put in the waypoints at the correct elevation to see how far their UAS will be able to see during its mission. 

Viewshed - Viewshed is the final tool in the 'Interactive Analysis' tab. This tool allows users to put in UAS sensor information like heading, tilt, horizontal angle, and vertical angle.

Viewshed tool demonstrating UAS' sensor view.

This tool is useful because it allows users to input specific sensor information in order to see what the sensor will see when it is collecting data. The picture above shows a point above the ground where a waypoint could be placed. The tilt is adjusted to -90 degrees, where the sensor is pointed straight down, and the surrounding box is the amount of land that the sensor will be able to view at a specific elevation.

Using all three of these tools in conjunction, a UAS team could get a pretty good idea of what to expect when they go out to perform their mission.

Satellite and UAS Imagery

After going through the navigation controls and the various tools that could be useful to UAS users, the lab had us look at satellite and UAS imagery. Below, the different types of imagery were separated into three types of UAS projects that a pilot may encounter in a UAS career. 

Vegetation Health - Vegetation health is very important in various jobs like farming and forestry. People could go in and monitor individual plants in person to see vegetation health, but this is very time consuming. With the use of special sensors, aircraft can be used to create false color maps that make vegetation health easy to interpret. The ArcGIS Online section of the Add Data tool, mentioned above, has many false color maps that can be viewed for analysis. One example is the USA NAIP (National Agricultural Imagery Program) which regularly images the United States with true color, NDVI, and false color infrared sensors. 

Map of the Lafayette area (Google earth on the left and USA NAIP NDVI on the right).

The NDVI (Normalized Difference Vegetation Index) shows vegetation health in a green-to-red spectrum. Red vegetation is unhealthy and bright green healthy. Only looking at the NDVI map, it was hard to understand what the dark green areas meant. Comparing the NDVI to Google Earth, it seems like urban areas get blocked out of the map. Google Earth showed that the patches in the bottom left of the image are farmland. The red patches are unhealthy, or perhaps recently harvested, whereas the bright green patches are healthy. 

USA NAIP Imagery: Color Infrared (Lafayette Area)

Another form of false color imagery used to monitor vegetation health is Color Infrared. Unlike NDVI, bright red indicates healthy vegetation and dull red indicates unhealthy vegetation. Additionally, color infrared highlights urban areas in blue. This is helpful because the urban areas have a high contrast to vegetation. Where the NDVI blocked out city areas, color infrared allows viewers to zoom in on the cities and see vegetation health within the city. Color infrared is also easier to interpret because the added detail allows users to understand the map area without the use of another map.

Disaster Relief - Another job in the UAS industry is disaster relief. This includes jobs like search and rescue and wildfire response. This lab, the focus for disaster relief was wildfire response. One of the map layers that can be viewed is the NASA MODIS (Moderate Resolution Imaging Spectroradiometer). One of the MODIS options in ArcGIS Online highlights thermal hotspots and fire activity. 

MODIS Thermal Hotspots and Fire Activity shows that there are wildfires all around the world.

Each red blip in the photo above represents a different wildfire. This map shows where the demand is for wildfire response. UAS operators could use this to locate wildfires in which they may be able to help response teams.

MODIS Fire Activity Map zoomed in on California.

When zoomed in, the map shows the affected areas of each wildfire. The wildfire points can also be clicked on to see information about the wildfire including how much of the fire is contained.

Mapping - One of the more simple tasks that can be performed with a UAS is mapping. Both of the potential UAS projects listed above include mapping, but regular mapping is also something UAS operators will likely encounter in their careers. 

USA NAIP True Color Image

The above image was also taken from the NAIP map layer. The map has pretty good detail. As you zoom in, the map increases its detail. While it has good detail for a map of the United States, the picture can only be zoomed in so far before it becomes blurry. In situations where someone wants a small area mapped out, satellites and planes are too far away to capture enough detail. UAS are often used in these cases because they can fly much closer to the ground and capture more detail. 

USA NAIP Map of area near West Lafayette

The last imagery looked at in this lab was UAS imagery of a burn sight near West Lafayette. Before showing that imagery, here is a photo taken from the NAIP map layer of the same area. The photo was zoomed in to an elevation around 360 meters. At this point, the NAIP map is blurry and begins to lose detail.

Martell RGB Map of area near West Lafayette

This is the UAS imagery of the same area. The elevation is also the roughly the same, within 10 meters. It is easy to see that the UAS imagery is much more detailed. 

Conclusion

ArcGIS Earth has very many useful tools in UAS for mission planning as well as analysis after the mission. In previous UAS classes, we used ArcGIS to analyze burn photos, but the focus was only on the images. I thought these software were only used after the mission takes place. Mission planning seems much more convenient when tools like the ones in ArcGIS Earth are used.