if [ ! -f "ossv-${OSSV_DIFF_NAME}-combined.vrt" ]; then
gdalbuildvrt -resolution highest -hidenodata "ossv-${OSSV_DIFF_NAME}-combined.vrt" ${OSSV_DIFF_NAME}/*.tif
fi
if [ ! -f "ossv-${OSSV_DIFF_NAME}-combined.vrt" ]; then
gdalbuildvrt -resolution highest -hidenodata "ossv-${OSSV_DIFF_NAME}-combined.vrt" ${OSSV_DIFF_NAME}/*.tif
fi