Beam Blockage Calculation using a DEM - polarvalues error

Hello all,

I try to follow the script on Beam Blockage Calculation using a DEM — wradlib. I set up my radar as given in the first section.

Then, as I have already downloaded my DEM geotiff-file, I changed the codeblock [7] to

fpath = "file/to/path/topography.tif"

ds =
rastervalues, rastercoords, crs = wrl.georef.extract_raster_dataset(ds, nodata=-9999.0)

# Clip the region inside our bounding box
ind = wrl.util.find_bbox_indices(rastercoords, rlimits)
rastercoords = rastercoords[ind[1] : ind[3], ind[0] : ind[2], ...]
rastervalues = rastervalues[ind[1] : ind[3], ind[0] : ind[2]]

# Map rastervalues to polar grid points
polarvalues = wrl.ipol.cart_to_irregular_spline(
    rastercoords, rastervalues, polcoords, order=3, prefilter=False

Unfortunately, I do get a ValueError in polarvalues:

ValueError: zero-size array to reduction operation minimum which has no identity 

Does someone know from where this comes from?


I have also faced this error. try to change the rlimits - (lonmin,latmin,lonmax,latmax) it will fix your error.

Thanks @Jagdish_jena,

that was also my first guess. @lou Your rlimits need to correspond to the rastercoords. You might also check the index ind values, if it contains useful values.