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Add a --nodata opt to override bogus nodata.

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Bogus nodata being, eg, -9999 for a uint8 dataset. rio-merge now
warns when the input file's nodata value is bogus and suggests
the use of --nodata for better results.
This commit is contained in:
Sean Gillies 2015-01-13 14:53:20 -07:00
parent 6258f460ca
commit 476e1188e2
2 changed files with 32 additions and 9 deletions
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2
rasterio/_base.pyx
View File

@ -286,7 +286,7 @@ cdef class DatasetReader(object):
if hband == NULL:
raise ValueError("Null band")
val = _gdal.GDALGetRasterNoDataValue(hband, &success)
if not success or val == -9999.0:
if not success:
val = None
self._nodatavals.append(val)
return self._nodatavals

39
rasterio/rio/merge.py
View File

@ -20,8 +20,10 @@ from rasterio.transform import Affine
help="Output bounds: left, bottom, right, top.")
@click.option('--res', nargs=2, type=float, default=None,
help="Output dataset resolution: pixel width, pixel height")
@click.option('--nodata', '-n', type=float, default=None,
help="Override nodata values defined in input datasets")
@click.pass_context
def merge(ctx, files, driver, bounds, res):
def merge(ctx, files, driver, bounds, res, nodata):
"""Copy valid pixels from input files to an output file.
All files must have the same number of bands, data type, and
@ -39,6 +41,7 @@ def merge(ctx, files, driver, bounds, res):
verbosity = (ctx.obj and ctx.obj.get('verbosity')) or 1
logger = logging.getLogger('rio')
try:
with rasterio.drivers(CPL_DEBUG=verbosity>2):
output = files[-1]
@ -48,6 +51,8 @@ def merge(ctx, files, driver, bounds, res):
first_res = first.res
kwargs = first.meta
kwargs.pop('affine')
nodataval = first.nodatavals[0]
dtype = first.dtypes[0]
if os.path.exists(output):
# TODO: prompt user to update existing file (-i option) like:
@ -55,8 +60,8 @@ def merge(ctx, files, driver, bounds, res):
# not overwritten
dst = rasterio.open(output, 'r+')
nodataval = dst.nodatavals[0]
dest = np.zeros((dst.count,) + dst.shape,
dtype=dst.dtypes[0])
dtype = dst.dtypes[0]
dest = np.zeros((dst.count,) + dst.shape, dtype=dtype)
else:
# Create new output file.
# Extent from option or extent of all inputs.
@ -88,13 +93,31 @@ def merge(ctx, files, driver, bounds, res):
dst = rasterio.open(output, 'w', **kwargs)
dest = np.zeros((first.count, output_height, output_width),
dtype=first.dtypes[0])
nodataval = first.nodatavals[0]
dtype=dtype)
if nodata is not None:
nodataval = nodata
if nodataval is not None:
dest.fill(nodataval)
else:
notdataval = 0
# Only fill if the nodataval is within dtype's range.
inrange = False
try:
info = np.iinfo(dtype)
inrange = (info.min <= nodataval <= info.max)
except ValueError:
try:
info = np.finfo(dtype)
inrange = (info.min <= nodataval <= info.max)
except:
pass
if inrange:
dest.fill(nodataval)
else:
logger.warn(
"Input file's nodata value, %s, is beyond the valid "
"range of its data type, %s. Consider overriding it "
"using the --nodata option for better results.",
nodataval, dtype)
for fname in reversed(files):
with rasterio.open(fname) as src: