Local-Area-Enhanced, 2.5-Meter Resolution Natural-Color and 
Color-Infrared Satellite-Image Mosaics of the Ahankashan 
Mineral District in Afghanistan

By Philip A. Davis

Data Series 709-Y

2013

U.S. Department of the Interior
U.S. Geological Survey


Abstract:

The U.S. Geological Survey (USGS), in cooperation with the 
U.S. Department of Defense Task Force for Business and 
Stability Operations, prepared databases for mineral-
resource target areas in Afghanistan. The purpose of the 
databases is to (1) provide useful data to ground-survey 
crews for use in performing detailed assessments of the 
areas and (2) provide useful information to private 
investors who are considering investment in a particular 
area for development of its natural resources. The set of 
satellite-image mosaics provided in this Data Series (DS) 
is one such database. Although airborne digital color-
infrared imagery was acquired for parts of Afghanistan in 
2006, the image data have radiometric variations that 
preclude their use in creating a consistent image mosaic 
for geologic analysis. Consequently, image mosaics were 
created using ALOS (Advanced Land Observation Satellite; 
renamed Daichi) satellite images, whose radiometry has been 
well determined (Saunier, 2007a,b). This part of the DS 
consists of the locally enhanced ALOS image mosaics for the 
Ahankashan mineral district, which has copper and gold 
deposits.

ALOS was launched on January 24, 2006, and provides 
multispectral images from the AVNIR (Advanced Visible and 
Near-Infrared Radiometer) sensor in blue (420-500 
nanometer, nm), green (520-600 nm), red (610-690 nm), and 
near-infrared (760-890 nm) wavelength bands with an 8-bit 
dynamic range and a 10-meter (m) ground resolution. The 
satellite also provides a panchromatic band image from the 
PRISM (Panchromatic Remote-sensing Instrument for Stereo 
Mapping) sensor (520-770 nm) with the same dynamic range 
but a 2.5-m ground resolution. The image products in this 
DS incorporate copyrighted data provided by the Japan 
Aerospace Exploration Agency ((c)JAXA,2007,2008, 2009, 
2010),but the image processing has altered the original 
pixel structure and all image values of the JAXA ALOS data, 
such that original image values cannot be recreated from 
this DS. As such, the DS products match JAXA criteria for 
value added products, which are not copyrighted, according 
to the ALOS end-user license agreement. 

The selection criteria for the satellite imagery used in 
our mosaics were images having (1) the highest solar-
elevation angles (near summer solstice) and (2) the least 
cloud, cloud-shadow, and snow cover. The multispectral and 
panchromatic data were orthorectified with ALOS satellite 
ephemeris data, a process which is not as accurate as 
orthorectification using digital elevation models (DEMs); 
however, the ALOS processing center did not have a precise 
DEM. As a result, the multispectral and panchromatic image 
pairs were generally not well registered to the surface and 
not coregistered well enough to perform resolution 
enhancement on the multispectral data. Therefore, it was 
necessary to (1) register the 10-m AVNIR multispectral 
imagery to a well-controlled Landsat image base, (2) mosaic 
the individual multispectral images into a single image of 
the entire area of interest, (3) register each panchromatic 
image to the registered multispectral image base, and (4) 
mosaic the individual panchromatic images into a single 
image of the entire area of interest. The two image-
registration steps were facilitated using an automated 
control-point algorithm developed by the USGS that allows 
image coregistration to within one picture element. Before 
rectification, the multispectral and panchromatic images 
were converted to radiance values and then to relative-
reflectance values using the methods described in Davis 
(2006). Mosaicking the multispectral or panchromatic images 
started with the image with the highest sun-elevation angle 
and the least atmospheric scattering, which was treated as 
the standard image. The band-reflectance values of all 
other multispectral or panchromatic images within the area 
were sequentially adjusted to that of the standard image by 
determining band-reflectance correspondence between 
overlapping images using linear least-squares analysis. The 
resolution of the multispectral image mosaic was then 
increased to that of the panchromatic image mosaic using 
the SPARKLE logic, which is described in Davis (2006). Each 
of the four-band images within the resolution-enhanced 
image mosaic was individually subjected to a local-area 
histogram stretch algorithm (described in Davis, 2007), 
which stretches each band's picture element based on the 
digital values of all picture elements within a 500-m 
radius. The final databases, which are provided in this DS, 
are three-band, color-composite images of the local-area-
enhanced, natural-color data (the blue, green, and red 
wavelength bands) and color-infrared data (the green, red, 
and near-infrared wavelength bands).

All image data were initially projected and maintained in 
Universal Transverse Mercator (UTM) map projection using 
the target area's local zone (41 for Ahankashan) and the 
WGS84 datum. The final image mosaics were subdivided into 
five overlapping tiles or quadrants because of the large 
size of the target area. The five image tiles (or 
quadrants) for the Ahankashan area are provided as embedded 
geotiff images, which can be read and used by most 
geographic information system (GIS) and image-processing 
software. The tiff world files (tfw) are provided, even 
though they are generally not needed for most software to 
read an embedded geotiff image.

Disclaimer:

Although these data have been processed successfully on a 
computer system at the U.S. Geological Survey, no warranty 
expressed or implied is made regarding the display or 
utility of the data on any other system, or for general or 
scientific purposes, nor shall the act of distribution 
constitute any such warranty. The U.S. Geological Survey 
shall not be held liable for improper or incorrect use of 
the data described and (or) contained herein.

Contact Information:

If you have any questions regarding this dataset please 
feel free to contact:

Philip A. Davis, Research Geologist
U.S. Geological Survey
2255 North Gemini Drive, Building 4
Flagstaff, AZ 86001
pdavis@usgs.gov
(928) 556-7084

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This Data Series includes the following Information. 
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DIRECTORY

index_maps

Ahankashan_Area-of-Interest_Index_Map.pdf -- Index map 
stored in Adobe Acrobat (PDF) format displaying the 
location of the Ahankashan mineral district within 
Afghanistan in the geographic coordinate system. Index map 
is also provided in jpeg format.

Ahankashan_Image_Index_Map.pdf -- Index map of the image 
products showing the extent of the target area and tile or 
quadrant scheme that was used to subdivide the image 
mosaics for the target area. This information is displayed 
on the topographic shaded-relief base map of Bohannon 
(2007a,b) in the UTM map projection and stored in both PDF 
and jpeg formats. 

image_files

Local-area-enhanced, 2.5-m natural-color and color-infrared 
satellite-image mosaics in geotiff format with their tfw 
files. All images with their tfw and metadata files are 
compressed with standard file compression software to 
facilitate file transfer.

metadata

AHANKASHAN_UTM_WGS84_Z41_NC_Qx.tif.txt -- FGDC compliant 
metadata files for each image tile or quadrant (designated 
by Qx). NC designates natural-color image data.

AHANKASHAN_UTM_WGS84_Z41_CIR_Qx.tif.txt -- FGDC compliant 
metadata files for each image tile or quadrant (designated 
by Qx). CIR designates color-infrared image data. 

shapefiles

Ahankashan_Image_Mosaic_Index.shp -- A shapefile showing 
the boundary for the area of interest.

index.html -- http://pubs.usgs.gov/ds/709/y/

1_readme.txt -- This file.

References Cited:

Bohannon, R.G., 2007a, Topographic map of quadrangle 3462, 
Herat (409) and Chesht-Sharif (410) quadrangles, 
Afghanistan: U.S. Geological Survey Open-File Report 2005-
1104-B, 1:250,000 scale, available at 
http://pubs.usgs.gov/of/2005/1104/B/.

Bohannon, R.G., 2007b, Topographic map of quadrangle 3464, 
Shahrak (411) and Kasi (412) quadrangles, Afghanistan:  
U.S. Geological Survey Open-File Report 2005-1105-B, 
1:250,000 scale, available at 
http://pubs.usgs.gov/of/2005/1105/B/.

Davis, P.A., 2006, Calibrated Landsat ETM+ nonthermal-band 
image mosaics of Afghanistan: U.S. Geological Survey Open-
File Report 2006-1345, 18 p., available at 
http://pubs.usgs.gov/of/2006/1345/.

Davis, P.A., 2007, Landsat ETM+ false-color image mosaics 
of Afghanistan: U.S. Geological Survey Open-File Report 
2007-1029, 22 p., available at 
http://pubs.usgs.gov/of/2007/1029/.

Saunier, S., 2007a, Final calibration/validation report, 
PRISM: GAEL Consultant report, 27 p., accessed April 23, 
2012, at http://earth.esa.int/pub/ESA_DOC/ALOS011.pdf.

Saunier, S., 2007b, Final calibration/validation report, 
AVNIR-2: GAEL Consultant report, 25 p., accessed April 23, 
2012, at http://earth.esa.int/pub/ESA_DOC/ALOS012.pdf.