gdalbuildvrt testing.vrt 6403_1_10m_z32.dem 6403_4_10m_z32.dem 6502_2_10m_z32.dem 6503_3_10m_z32.dem 6503_2_10m_z32.dem
gdalwarp -te 569312 5872503 580988 5878088 testing.vrt small.tif
gdaldem hillshade -of PNG small.tif testingut.png
gdal_contour -a height small.tif small.shp -i 5