# QuickBird

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## Overview

Scenes are 16.5km x 16.5km.

Data is 11-bit integers stored in a 16-bit integer field. Thus band minimum = 0, band maximum = 2047. (${\displaystyle 2^{11}-1}$)

Multi-spectral bands (2.44 - 2.88m pixel res)

```band 1 = blue
2 = green
3 = red
4 = Near IR
```

Panchromatic band (61-72cm pixel res)

## Import

Data comes in a GeoTiff file. Use the `gdalinfo` program to check projection settings. You can then set up a location based on this, e.g. UTM zone 23 South.

• Once in the appropriate location import with the r.in.gdal module

## Cleanup

Rename the NIR band

```g.rename QBird_Multichrom.4,QBird_Multichrom.NIR
```

Red and blue bands are swapped, so fix that by renaming them. (see [1])

```g.rename QBird_Multichrom.blue,QBird_Multichrom.realred
g.rename QBird_Multichrom.red,QBird_Multichrom.blue
g.rename QBird_Multichrom.realred,QBird_Multichrom.red
```

No data is set to 0, so convert that to NULL with r.null:

```for BAND in red green blue NIR ; do
r.null QBird_Multichrom.\$BAND setnull=0
echo \$BAND:
r.info -r QBird_Multichrom.\$BAND
echo
done
```

Set color tables appropriately for 11-bit data:

```for BAND in red green blue NIR ; do
r.colors QBird_Multichrom.\$BAND color=rules << EOF
0 black
2047 white
EOF
done
```

It is not necessarily needed, but if you wish to rescale to 8-bit data you can use r.rescale as follows:

```for BAND in red green blue NIR ; do
r.rescale in=QBird_Multichrom.\$BAND from=0,2047 \
out=QBird_Multichrom255.\$BAND to=0,255
done
```

Display the 3-band RGB image:

```d.rgb r=QBird_Multichrom.red g=QBird_Multichrom.green b=QBird_Multichrom.blue
```

If the image is excessively dark you might try using the i.landsat.rgb module to auto-balance the colors and redraw:

```i.landsat.rgb r=QBird_Multichrom.red g=QBird_Multichrom.green b=QBird_Multichrom.blue
d.redraw
```