Changes Near the Giza Necropolis Visible in Landsat Images

By
Megan Sprague
Fall, 2013
ES 775 Advanced Image Processing
Emporia State University

(Wikimedia Commons)

Table of Contents
Abstract Landsat Background Information
Method Results
Conclusion References

Abstract

This project is for an advanced image processing class. The purpose of this project was to discover if changes to the area around the Giza Necropolis could be ascertained by using Landsat imagery, especially changes in the excavation sites. Various Landsat images were acquired and processed in the IDRISI Selva program. These images were then compared to each other in order to determine any changes.

Landsat Background Information

The Landsat program is a series of satellites that were designed to take multispectral images of the Earth. Since 1972 there have been 7 Landsat satellites in orbit. Landsats 1-5 were equiped with Multispectral Scanners or MSS. Landsats 4 and 5 had Thematic Mappers or TM and Landsat 7 had an Enhanced Thematic Mapper Plus (ETM+). Landsat 8 is equiped with the Operational Land Imager or OLI (Aber). There are usually two active satellites in orbit at one time. At this time those two are Landsat 7 and Landsat 8. In 2003 the Scan Line Corretor (SLC) on Landsat 7 failed and subsequent images need to be heavily processed before use.

Landsat OLI and ETM+ scanner comparison
Landsat 8
OLI band (m)
GSD
(m)
Landsat 7
ETM+ band (m)
Color Primary use
1. 0.4330.453
30
none
Violet-blue Shallow water, aerosols
2. 0.4500.515
30
1. 0.4500.515
Blue-green Shallow water, land cover
3. 0.5250.600
30
2. 0.5250.605
Green Vegetation, land cover
4. 0.6300.680
30
3. 0.6300.690
Red Minerals, soils, land cover
5. 0.8450.885
30
4. 0.7750.900
Near-infrared Vegetation, NDVI
6. 1.5601.660
30
5. 1.5501.750
Mid-infrared Soil moisture, minerals
7. 2.1002.300
30
7. 2.0902.350
Mid-infrared Soil moisture, minerals
8. 0.5000.680
15
8. 0.5200.900
Panchromatic Image sharpening
9. 1.3601.390
30
none
Mid-infrared Cirrus clouds

Figure-1. Table of Landsat Bands (Aber)

Method

These images are from Landsats 7 (1999-2003) and 8 (2013) and one from Landsat 4 (1989). The Landsat datasets were downloaded from the USGS website EarthExplorer where there is data available from several different satellites. The Landsat 7 images are from before the SLC failure in order to avoid complcations. The files come in a compressed form and need to be extracted. After extraction the GeoTIFF files were then imported into the IDRISI Selva program. GeoTIFF and IDRISI files are rather large and all extra files should be deleted to save space. The Landsat 8 images were processed into composites first, then the Landsat 7 images and finally the Landsat 4 image. Bands 2, 6 and 7 were chosen for their measurements of changes in soil and land cover. Landsat 4 and 7 bands 1, 5 and 4 were chosen for the same reasons and to keep the images as similar as possible. These composites were then zoomed in to the site of the Giza Necropolis and the area near the Pyramids was carefully examined.

A pan-sharpening was then attempted. The panchromatic band 8 is used in the pan-sharpening process, but it has a 15x15m resolution rather than the other bands 30x30m resolution. In order to pan-sharpen an image these other bands must be expanded by a factor of 2. After the expansion of the other bands, when the pan-sharpening process was attempted a strange error was discovered. The expansion of the bands resulted in a situation where they had one more row and column than band 8. This makes the pan-sharpening impossible to complete at this time.

A 123 composite or a natural color composite was then made of the Landsat 4 image to show the city of Cairo in relation to the Giza Necropolis. And windows were created in the 1989 image and one of the 2013 images for a before and after image.

Results

On their own the 267 Landsat 8 composites and the 154 Landsats 4 and 7 composites do not have enough resolution to determine detailed amounts of change. It is possible to see change but just barely. Since there was an issue with the pan-sharpening process it is unknown at this time if using band 8 would have made changes easier to see.

Figure-2. The city of Cairo in 1989. The red dot is where the Giza Necropolis is located.

Figure-3. Giza Necropolis. August 26, 2013

The most interesting change was in what appears to be the community of Hadabet El-Ahram (Google Maps). This community or suburb appears to be strictly planned out. The roads were laid out by 1989 and the buildings slowly filled in the open spaces over the next two decades. The following images show its progression.

Figure-4. August 9, 1989

Figure-5. July 11, 1999

Figure-6. December 2, 1999

Figure-7. August 23, 2000

Figure-8. November 11, 2000

Figure-9. January 30, 2001

Figure-10. August 8, 2002

Figure-11. May 3, 2003

Figure-12. August 3, 2013

before
after

Figure-13. A comparision of the Giza Necropolis in 1989 and 2013.

Conclusion

It is possible to see changes in the excavation sites at the Giza Necropolis, but just barely. Landsat imagery of 30x30m resolution should most likely be used for viewing changes on a slightly larger scale such as the development of the suburb near the Necropolis. Or perhaps in an area with a wider variety of surface sediments. Imagery of 15x15m resolution might be more useful, but that is unknown at this time.

References

  • Aber, J.S. 2013. ES 775 Lab 5 Landsat 8 OLI, Accessed online <http://academic.emporia.edu/aberjame/es775/lab05/lab05.htm> November 2013.

  • USGS. Landsat Archive, Accessed online <http://earthexplorer.usgs.gov/> November 2013.

  • Google Maps. 2013., Accessed online <https://maps.google.com/> November 2013.