AT 309 Week 4: Exploring ESRI Landsat Explorer

Introduction

Lab 4, in AT309, had the class doing an online tutorial for ESRI's Landsat Explorer application. Landsat Explorer allows users to look at satellite imagery of Earth and apply different spectral bands to highlight various objects on the map.

The tutorial shows users how to change the spectral resolution while explaining what the different bands are used for. The satellite imagery in Landsat Explorer is continuously updated which means ESRI has imagery dating back to the 1970s. One of the other features in Landsat Explorer allows users to look at all the imagery taken over the years. 

Spectral and temporal resolution are very important aspects of UAS jobs. UAS are often equipped with spectral sensors to collect data that is used in ways similar to satellite data. Temporal data is also often collected with UAS. Unmanned systems are used in construction to show progress when buildings are being built.

Color Infrared (5,4,3)

Color infrared is the first spectral resolutions shown in the ESRI tutorial. It uses a near infrared band which makes it useful in analyzing vegetation. Due to chlorophyll, vegetation is highly reflective of infrared waves. Vegetation shows up as bright red in color infrared. 

Purdue University in Color Infrared

The image above was taken from ESRI. All the red areas are areas that are covered in vegetation. Some of the red areas are very bright and other areas are a darker shade of red. Color infrared is useful for analyzing vegetation because healthy vegetation will be bright red and less healthy vegetation will be more a more dull red.

Agricultural Band (6,5,2)

Another spectral band that is useful for monitoring vegetation is the agricultural band. This band highlights vegetation in green. While color infrared is useful for looking at vegetation health, the agricultural band makes it easier to see the health of vegetation. In the agricultural band, vigorous vegetation is bright green, healthy vegetation is a darker green, and stressed vegetation is dull green. 

Midwestern Plains in the Agricultural Band

The image above is looking at plains in the Midwest United States. This area is good for showing off the agricultural band as it shows many different green patches. Although the patches are all connected to each other, they show up as different shades. The darker areas show where the healthiest vegetation is.

The Badlands in the Agricultural Band

This image shows the Badlands in California under the same agricultural band as the image with the plains. The first thing to notice is that this image has almost no green in it. The Badlands are a desert area with little vegetation. In the top right area of the photo, there is a small amount of dull green vegetation. While there is some vegetation in the Badlands, it is likely stressed which would make sense considering the desert area. There is also some brighter green vegetation surrounding the body of water in the middle of the photo. This also makes sense as vegetation would be able to thrive better by water.

Temporal Resolution

The next part of the ESRI tutorial shows users the time setting in Landsat Explorer. Temporal data is good for showing the way Earth has changed over large periods of time. This can be useful for showing construction progress, vegetation growth, and anything else that changes over time. 

Las Vegas (1975) in Natural Color

The photo above was taken from a satellite in 1975. The older satellite imagery has less options for spectral bands. The Las Vegas satellite imagery, from 1975, only used the natural color band. The image quality is lower than newer images as satellite imagery has gotten better since the 1970s. In 1975, Las Vegas' airport was located at the bottom edge of Las Vegas.

Las Vegas (2020) in the Agricultural Band

This image was taken in September of 2020. I chose the agricultural band for this photo as the natural color band appeared dull and the agricultural band highlights Las Vegas better. Comparing the two images shows that Las Vegas has grown out quite a bit since 1975. The airport mentioned above is now more towards the center of Las Vegas.

Relating to UAS

The various spectral settings and the temporal setting used in Landsat Explorer are very practical to UAS as a tool. Unmanned systems could benefit this type of application by integrating the large amount of satellite data with UAS data. Satellite imagery is good for imaging all of Earth but the resolution is not very detailed when zoomed in. UAS could be used to capture more detailed data of high profile areas. UAS could also be used to capture this data more often than satellites do. The temporal data provided in Landsat Explorer was taken at worst years in between and at best two weeks in between. Unmanned systems could be used to capture temporal data daily or even more often. Eventually UAS could possibly be used to create live maps that are always being updated.