Methods

I focused on studying the Volcanoes National Park, located on the borders of Rwanda, Democratic Republic of Congo, and Uganda. The images were either produced by using the ENVI software or obtained from websites that provided satellite images of the study area. Observing the growth and reduction of vegetation in this park over the years is important in studying the Virunga mountain gorillas' habitat as they depend highly on the vegetation for food resources and shelter.

Landsat Data

The Landsat Data is extremely helpful in creating time series images of the study area in order to see how the region has changed over time. Once downloaded, the Landsat Data could be uploaded into ENVI and used to create subsets of places of interest, density slices, NDVIs, 3D models, etc.

To obtain Landsat data, it was easiest to simply Google Landsat, which brought me to the Landsat Program page on the National Aeronautics and Space Administration (NASA) site. From there I selected "Images", then "Find Your Location", and then "USGS Global Visualization (Glovis) Viewer" which used Landsat 4-5 Thematic Mapper at 240 meter spatial resolution. From there I simply searched my location and selected the images with the least cloud cover in order to have the maximum amount of area available to study. I downloaded the images if it was available for download, opened the containing folder after the download was complete, and I double unzipped the file, which provided me with the multiple bands I would use for ENVI.

I could also find Landsat data by searching "Earthexplorer" on Google, selecting the "USGS EarthExplorer: Satellite Images, Aerial Photographs and Maps" link, checking all the boxes for Landsat data I wanted, searching my study area, and clicking "search". Any available data Earthexplorer has will be pulled up with a preview of the image. However, not all images are available for download.

ENVI

Once I downloaded the files and double unzipped them, I used ENVI to perform certain tasks that would display the information on vegetation and land composition I was studying for the Volcanoes National Park. I always started by selecting "Open Image File" from the Power bar and I selected the 1st, 2nd, 3rd, and 4th bands of the file. I would then select the order of band for RGB images; 321 for original color or 323 to show vegetation in dark greens against light purples, then click "Load". These images formed the basis for creating density slices, 3D models, etc.

Density Slices

The image above compares two density slices of the Volcanoes National Park. I obtained the data from the USGS Global Visualization Viewer which used Landsat 4-5 Thematic Mapper at 240 meter spatial resolution. Using ENVI, I did a subset of the Volcanoes National Park from the original image for 1987 and 2005. I then performed a density slice of both images to show the extent of vegetation as well as the density of vegetation. By comparing the two, it seems that some parts of the park have grown over the years while some parts have been deforested.

3D Model

This image was made using data obtained from EarthExplorer of Volcanoes National Park. The image is of the National Park in February 2005, captured by the Landsat 7 Enhanced Thematic Mapper Plus. Using the 3D Surface View tool on ENVI, I was able to make this 3D model of the national park and really show the contrast between the lowlands and the volcanoes by increasing the vertical exaggeration.

Elevation Data

Using Earthexplorer I was able to download Digital Elevation Data which uses Shuttle Radar Topography Mission 1 Arc and 3 Arc Second Digital Terrain Elevation Data. Then, by using ENVI I was able to make the four images, starting from the top left image and going clockwise: Topographic, Elevation, Aspect, and Shaded Relief.

Other Data

I obtained other data through doing research on various journals, which I found using Google Scholar, as well as searching satellite imaging sites for available images on my study area. These other images were obtained through the following satellites and sensors: Landsat TM, Landsat TM5 (resolution is 28.5 ), GeoEye, IKONOS (spatial resolution of 1 meter), and Space Shuttle/SIR-C/X-SAR. I also used University of Maryland's "Firefly" application which allowed me to collect data on fires that have been recorded for the past several years near or in my study area.

Data Analysis

I analyzed the data I created on ENVI as well as the data I found on other sites and journals by comparing them and seeing whether there were any correlations between patterns that were occurring and events that were happening. For example I was able to compare the data from a population table that provided a census of gorillas per year and I could see whether there was a correlation between the decrease in population, a decrease in vegetation, and an increase in civil warfare within Rwanda and the surrounding regions. By taking historical information and comparing it to numerical data and satellite imaging, we are able to connect the dots and create a story that sheds light on how something such as war can affect wildlife.