[gdal-dev] assigning vertical datum to image files

[Hermann Peifer]

About your initial problem:
 > but gdalbuildvrt complained, informing me that
 > they were not in the same projection.

What about using the below gdalbuildvrt option?

Hermann

-allow_projection_difference:
(starting with GDAL 1.7.0) When this option is specified, the utility 
will accept to make a VRT even if the input datasets have not the same 
projection. Note: this does not mean that they will be reprojected. 
Their projection will just be ignored.

Source: http://www.gdal.org/gdalbuildvrt.html


On 2015-06-08 21:01, Newcomb, Doug wrote:
> Hi Folks,
> I have a directory of 783 .img format Lidar - based  DEMs in the same
> projection, North Carolina State Plane  Feet (2011) , NAD 83 , NVD88.  I
> was going to use gdalbuildvrt to create a single virtual image for the
> area, but gdalbuildvrt complained, informing me that they were not in
> the same projection.
>
> A couple of quick bash scripts/commands
>
> for x in *.img; do gdalinfo $x >>img_info.txt;done
>
> and
> grep PROJCS img_info.txt|sort|uniq -c
>
> gives me the following:
>
>      437 PROJCS["NAD_1983_2011_StatePlane_North_Carolina_FIPS_3200_Ft_US",
>      346 PROJCS["NAD_1983_StatePlane_North_Carolina_FIPS_3200_Feet_2011",
>
> gdalinfo gives the following for each type of file ( origin section
> clipped out) :
>
> Driver: HFA/Erdas Imagine Images (.img)
> Files: D05_37_20878102_20141231.img
>         D05_37_20878102_20141231.img.aux.xml
> Size is 1000, 1000
> Coordinate System is:
> PROJCS["NAD_1983_2011_StatePlane_North_Carolina_FIPS_3200_Ft_US",
>      GEOGCS["GCS_NAD_1983_2011",
>          DATUM["NAD_1983_2011",
>              SPHEROID["GRS_1980",6378137.0,298.257222101]],
>          PRIMEM["Greenwich",0.0],
>          UNIT["Degree",0.017453292519943295]],
>      PROJECTION["Lambert_Conformal_Conic_2SP"],
>      PARAMETER["False_Easting",2000000.0],
>      PARAMETER["False_Northing",0.0],
>      PARAMETER["Central_Meridian",-79.0],
>      PARAMETER["Standard_Parallel_1",34.3333333333333],
>      PARAMETER["Standard_Parallel_2",36.1666666666667],
>      PARAMETER["Latitude_Of_Origin",33.75],
>      UNIT["Foot_US",0.30480060960121924],
>      VERTCS["NAVD_1988_Foot_US",
>          VDATUM["North_American_Vertical_Datum_1988"],
>          PARAMETER["Vertical_Shift",0.0],
>          PARAMETER["Direction",1.0],
>          UNIT["Foot_US",0.3048006096012192]]]
>
>
> Driver: HFA/Erdas Imagine Images (.img)
> Files: D05_37_20957301_20141231.img
>         D05_37_20957301_20141231.img.aux.xml
> Size is 1000, 1000
> Coordinate System is:
> PROJCS["NAD_1983_StatePlane_North_Carolina_FIPS_3200_Feet_2011",
>      GEOGCS["GCS_NAD_1983_2011",
>          DATUM["NAD_1983_2011",
>              SPHEROID["GRS_1980",6378137.0,298.257222101]],
>          PRIMEM["Greenwich",0.0],
>          UNIT["Degree",0.0174532925199433]],
>      PROJECTION["Lambert_Conformal_Conic_2SP"],
>      PARAMETER["False_Easting",2000000.002616666],
>      PARAMETER["False_Northing",0.0],
>      PARAMETER["Central_Meridian",-79.0],
>      PARAMETER["Standard_Parallel_1",34.33333333333334],
>      PARAMETER["Standard_Parallel_2",36.16666666666666],
>      PARAMETER["Latitude_Of_Origin",33.75],
>      UNIT["Foot_US",0.30480060960121924],
>      VERTCS["NAVD_1988_Foot_US",
>          VDATUM["North_American_Vertical_Datum_1988"],
>          PARAMETER["Vertical_Shift",0.0],
>          PARAMETER["Direction",1.0],
>          UNIT["Foot_US",0.3048006096012192]]]
>
>
>
> In theory, these should all be EPSG:6543, so just assigning the correct
>   horizontal projection/datum with the epsg code should make things
> usable. (i.e,
> gdal_translate -a_"srs epsg:6543" --config GDAL_CACHEMAX 512 -of GTiff
> -co COMPRESS=DEFLATE -co PREDICTOR=3 in.img out.tif )  ( Thank you for
> the EPSG:6543 projection support in GDAL 2.0!)
>
> However, this only assigns the horizontal infomation, how does one
> assign a vertical datum with a horizontal EPSG code?
>
> I see the NVD88 code in vertcs.csv , but how would I implement it in the
> above command?
>
> Using gdal 2.0 Beta2
>
>
> Doug
> --
> Doug Newcomb
> USFWS
> Raleigh, NC
> 919-856-4520 ext. 14 doug_newcomb at fws.gov <mailto:doug_newcomb at fws.gov>
> ---------------------------------------------------------------------------------------------------------
> The opinions I express are my own and are not representative of the
> official policy of the U.S.Fish and Wildlife Service or Dept. of the
> Interior.   Life is too short for undocumented, proprietary data formats.
>
>
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