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#!/usr/bin/env python3
import os
from osgeo import gdal
import epr
epr_to_gdal_type = {
epr.E_TID_UNKNOWN: gdal.GDT_Unknown,
epr.E_TID_UCHAR: gdal.GDT_Byte,
epr.E_TID_CHAR: gdal.GDT_Byte,
epr.E_TID_USHORT: gdal.GDT_UInt16,
epr.E_TID_SHORT: gdal.GDT_Int16,
epr.E_TID_UINT: gdal.GDT_UInt32,
epr.E_TID_INT: gdal.GDT_Int32,
epr.E_TID_FLOAT: gdal.GDT_Float32,
epr.E_TID_DOUBLE: gdal.GDT_Float64,
# epr.E_TID_STRING: gdal.GDT_Unknown,
# epr.E_TID_SPARE: gdal.GDT_Unknown,
# epr.E_TID_TIME: gdal.GDT_Unknown,
}
def epr2gdal_band(band, vrt): # noqa: C901, PLR0914
product = band.product
dataset = band.dataset
record = dataset.read_record(0)
field = record.get_field_at(band._field_index - 1) # noqa: SLF001
ysize = product.get_scene_height()
xsize = product.get_scene_width()
if isinstance(vrt, gdal.Dataset):
if (vrt.RasterYSize, vrt.RasterXSize) != (ysize, xsize):
raise ValueError("dataset size do not match")
gdal_ds = vrt
elif os.path.exists(vrt):
gdal_ds = gdal.Open(vrt, gdal.GA_Update)
if gdal_ds is None:
raise RuntimeError(f"unable to open {vrt!r}")
driver = gdal_ds.GetDriver()
if driver.ShortName != "VRT":
raise TypeError(
f"unexpected GDAL driver ({driver.ShortName}). "
f"VRT driver expected"
)
else:
driver = gdal.GetDriverByName("VRT")
if driver is None:
raise RuntimeError("unable to get driver 'VRT'")
gdal_ds = driver.Create(vrt, xsize, ysize, 0)
if gdal_ds is None:
raise RuntimeError(f"unable to create {vrt!r} dataset")
filename = os.pathsep.join(product.file_path.split("/")) # denormalize
offset = dataset.get_dsd().ds_offset + field.get_offset()
line_offset = record.tot_size
pixel_offset = epr.get_data_type_size(field.get_type())
if band.sample_model == epr.E_SMOD_1OF2:
pixel_offset *= 2
elif band.sample_model == epr.E_SMOD_2OF2:
offset += pixel_offset
pixel_offset *= 2
options = [
"subClass=VRTRawRasterBand",
f"SourceFilename={filename}",
f"ImageOffset={offset}",
f"LineOffset={line_offset}",
f"PixelOffset={pixel_offset}",
"ByteOrder=MSB",
]
gtype = epr_to_gdal_type[field.get_type()]
ret = gdal_ds.AddBand(gtype, options=options)
if ret != gdal.CE_None:
raise RuntimeError(f"unable to add VRTRawRasterBand to {vrt!r}")
gdal_band = gdal_ds.GetRasterBand(gdal_ds.RasterCount)
gdal_band.SetDescription(band.description)
metadata = {
"name": band.get_name(),
"dataset_name": dataset.get_name(),
"dataset_description": dataset.description,
"lines_mirrored": str(band.lines_mirrored),
"sample_model": epr.get_sample_model_name(band.sample_model),
"scaling_factor": str(band.scaling_factor),
"scaling_offset": str(band.scaling_offset),
"scaling_method": epr.get_scaling_method_name(band.scaling_method),
"spectr_band_index": str(band.spectr_band_index),
"unit": band.unit if band.unit else "",
"bm_expr": band.bm_expr if band.bm_expr else "",
}
gdal_band.SetMetadata(metadata)
return gdal_ds
def epr2gdal(product, vrt, *, overwrite_existing: bool = False):
if isinstance(product, str):
filename = product
product = epr.open(filename)
ysize = product.get_scene_height()
xsize = product.get_scene_width()
if os.path.exists(vrt) and not overwrite_existing:
raise ValueError(f"unable to create {vrt!r}. Already exists")
driver = gdal.GetDriverByName("VRT")
if driver is None:
raise RuntimeError("unable to get driver 'VRT'")
gdal_ds = driver.Create(vrt, xsize, ysize, 0)
if gdal_ds is None:
raise RuntimeError(f"unable to create {vrt!r} dataset")
metadata = {
"id_string": product.id_string,
"meris_iodd_version": str(product.meris_iodd_version),
"dataset_names": ",".join(product.get_dataset_names()),
"num_datasets": str(product.get_num_datasets()),
"num_dsds": str(product.get_num_dsds()),
}
gdal_ds.SetMetadata(metadata)
mph = product.get_mph()
metadata = str(mph).replace(" = ", "=").split("\n")
gdal_ds.SetMetadata(metadata, "MPH")
sph = product.get_sph()
metadata = str(sph).replace(" = ", "=").split("\n")
gdal_ds.SetMetadata(metadata, "SPH")
for band in product.bands():
epr2gdal_band(band, gdal_ds)
# @TODO: set geographic info
return gdal_ds
if __name__ == "__main__":
filename = "MER_LRC_2PTGMV20000620_104318_00000104X000_00000_00000_0001.N1"
vrtfilename = os.path.splitext(filename)[0] + ".vrt"
gdal_ds = epr2gdal(filename, vrtfilename)
with epr.open(filename) as product:
band_index = product.get_band_names().index("water_vapour")
band = product.get_band("water_vapour")
eprdata = band.read_as_array()
unit = band.unit
lines_mirrored = band.lines_mirrored
scaling_offset = band.scaling_offset
scaling_factor = band.scaling_factor
gdal_band = gdal_ds.GetRasterBand(band_index + 1)
vrtdata = gdal_band.ReadAsArray()
if lines_mirrored:
vrtdata = vrtdata[:, ::-1]
vrtdata = vrtdata * scaling_factor + scaling_offset
print("Max absolute error:", abs(vrtdata - eprdata).max())
# plot
from matplotlib import pyplot as plt
plt.figure()
plt.subplot(2, 1, 1)
plt.imshow(eprdata)
plt.grid()
cb = plt.colorbar()
cb.set_label(unit)
plt.title("EPR data")
plt.subplot(2, 1, 2)
plt.imshow(vrtdata)
plt.grid()
cb = plt.colorbar()
cb.set_label(unit)
plt.title("VRT data")
plt.show()
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