import numpy, sys
from osgeo import gdal, ogr
from osgeo.gdalconst import *

gdal.UseExceptions()

ds = gdal.Open('H:/Threshold/nsdvi_range.tif'
srcband = ds.GetRasterBand(1)
dst_layername = 'multitemporal'
drv = ogr.GetDriverByName('ESRI Shapefile')
dst_ds = drv.CreateDataSource( dst_layername + '.shp' )
dst_layer = dst_ds.CreateLayer(dst_layername, srs = None )
gdal.Polygonize( srcband, None, dst_layer, -1, [], callback=None )