2 Image Fusion: LANDSAT-7 - Brovey transform

An illustrative example of visually improving a LANDSAT-7 scene can be done with the Brovey transformation. Here three multispectral channels (28.5m res.) and the panchromatic channel (14.25m res.) are merged in this process to three new Red, Green, Blue channels. After importing the prepared LANDSAT-7 subscene for Spearfish we run:

     i.fusion.brovey -l ms1=tm.2 ms2=tm.4 ms3=tm.5 pan=pan out=brovey

     g.region -p rast=brovey.red

 
       r.composite r=brovey.red g=brovey.green b=brovey.blue $\backslash$

               out=tm.brovey

     d.rast tm.brovey

Figure 15: NVIZ showing a LANDSAT-7 Brovey fusion composite

The input channels have to be 2, 4, 5 and the panchromatic channel and flag '-l' for the LANDSAT-7 sensor. Then we set the GRASS region settings to one of the resulting high resolution channels and create a new map from the three new R, G, B Brovey channels. We can display this map using the GIS manager or QGIS. Comparing to tm.4 or other channels you can observe the improved spatial resolution.

We can also drape the result of the image fusion over the high resolution DEM with NVIZ (see figure 15):

     nviz elevation.10m col=tm.brovey