[gdal-dev] BAG File has Zero Pixel Size

Even Rouault even.rouault at spatialys.com
Wed Feb 24 14:26:25 PST 2021


Geoff,

There have been some issues with some BAG formulations in recent GDAL versions 
(probably 3.0 indeed). I've verified with GDAL 3.1.3 or 3.2.1 that this file 
can ber read correctly again.

Even

> Hello,
> 
> I'm relatively new to GDAL and have a question about some confusing behavior
> when reading BAG files using C++.  I'll put more details below but the TLDR
> is that while working with an older version of GDAL included with Ubuntu
> 16.04 I was able to read a file correctly but when working with the same
> file on Centos 8 the x and y pixel lengths are reported as zero.  I don't
> know if it's a problem with the data set being made for an old version of
> GDAL, or if something else has changed that I haven't accounted for.
> 
> The file in question is
> H12280_MB_1m_MLLW_Combined.bag.gz<https://data.ngdc.noaa.gov/platforms/ocea
> n/nos/coast/H12001-H14000/H12280/BAG/H12280_MB_1m_MLLW_Combined.bag.gz> at 
> Report for H12280
> (noaa.gov)<https://www.ngdc.noaa.gov/nos/H12001-H14000/H12280.html> and I'm
> following the "getting-dataset-information" part of the Raster API tutorial
> at gdal.org (Raster API tutorial - GDAL
> documentation<https://gdal.org/tutorials/raster_api_tut.html#getting-datase
> t-information>) for C++.
> 
> When printing out the dataset information on Ubuntu 16.04 with
> libgdal-dev-1.11.3+dfsg-3build2 I get:
> 
> Driver: BAG/Bathymetry Attributed Grid
> Size is 390x527x2
> Projection is `PROJCS["UTM Zone 10, Northern Hemisphere",GEOGCS["WGS
> 84",DATUM["WGS_1984",SPHEROID["WGS
> 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],TOWGS84[0,0,0,0,0,0,0],
> AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNI
> T["degree",0.0174532925199433,AUTHORITY["EPSG","9108"]],AUTHORITY["EPSG","43
> 26"]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",0],PA
> RAMETER["central_meridian",-123],PARAMETER["scale_factor",0.9996],PARAMETER[
> "false_easting",500000],PARAMETER["false_northing",0],UNIT["Meter",1]]'
> Origin = (525490.000000,5287130.000000)
> Pixel Size = (20.000000,-20.000000)
> 
> When printing out the dataset information from the same file on Centos 8
> with gdal-devel-3.0.4-5.el8.x86_64 I get:
> 
> Driver: BAG/Bathymetry Attributed Grid
> Size is 390x527x2
> Projection is `PROJCS["unnamed",GEOGCS["WGS
> 84",DATUM["WGS_1984",SPHEROID["WGS
> 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"
> ]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925
> 199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4326"]],PROJECTION["Trans
> verse_Mercator"],PARAMETER["latitude_of_origin",0],PARAMETER["central_meridi
> an",-123],PARAMETER["scale_factor",0.9996],PARAMETER["false_easting",500000]
> ,PARAMETER["false_northing",0],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS
> ["Easting",EAST],AXIS["Northing",NORTH]]' Origin =
> (525500.000000,5276600.000000)
> Pixel Size = (0.000000,-0.000000)
> 
> In particular the Pixel Size is 0 by 0 when it should be 20 by -20.  There
> are some other differences, like the fact that the UTM zone doesn't seem to
> show up in the output of the newer version, but I don't quite know what to
> make of it.  Any advice would be appreciated.
> 
> Thanks.
> 
> Geoff.


-- 
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