Description

The Naval Research Laboratory captured 1 meter resolution aerial photography for Afghanistan from 2004-2006. NRL's high-resolution, terrain-corrected imagery offers an unprecedented level of precision for previously uncharted areas of Afghanistan.

About the Data

Methodology

The raw imagery was obtained programmatically from the USGS Afghanistan Map Server, and subsequently processed using the open-source library Geospatial Data Abstraction Library (GDAL)

#!/bin/bash
export GDAL_CACHEMAX=3000
ADDO="2 4 8 16 32 64 128 256 512 1024 2048 4096 8192"
FILES=('/afghan/nrl/196/196241990');
let ACTIVE=0
for FILE in ${FILES[@]}; do
	(wget \
	    http://afghanistan.cr.usgs.gov$FILE.tif.bz2 && \
	IMAGE=$(echo $FILE |  sed -E "s_/afghan/nrl/[0-9]+/(.*)_\1_g") &&\
	bunzip2 \
	   -f \
	   $IMAGE.tif.bz2 && \
	gdalwarp \
	   -r lanczos \
	   -multi \
	   -wm 1000 \
	   -srcnodata "0 0 0" \
	   -dstnodata "0 0 0" \
	   -dstalpha \
	   -wo OPTIMIZE_SIZE=TRUE \
	   -wo UNIFIED_SRC_NODATA=YES \
	   -t_srs EPSG:3785 \
	   -co COMPRESS=LZW \
	   -co TILED=YES \
	   $IMAGE.tif \
	   ${IMAGE}_3785.tif && \
	gdaladdo \
	    -r cubic \
	    --config COMPRESS_OVERVIEW LZW \
	    ${IMAGE}_3785.tif \
	    $ADDO) &
   let ACTIVE=$ACTIVE+1
   if [ "$ACTIVE" -eq "4" ]; then
      wait
     let ACTIVE=0
   fi
done
gdalbuildvrt  \
    -resolution highest \
    combined.vrt \
    afghanistan-open-data-project/imagery/*3785.tif && \
cat combined.vrt |\
    sed \
       -E \
       's_([123])</SourceBand>_\1</SourceBand><LUT>47:1,90:110,160:255</LUT>_g' > tmp && \
mv -f tmp combined.vrt &&\
rm combined.vrt.ovr &&\
gdaladdo \
    -r cubic \
    -ro \
    --config COMPRESS_OVERVIEW LZW \
    combined.vrt \
    $ADDO

About