[GRASS-user] v.proj fails: no shift table

Thu Sep 15 00:42:57 PDT 2016

On Thu, Sep 15, 2016 at 1:02 AM, Rich Shepard <rshepard at appl-ecosys.com>
wrote:
>   The target location has these PROJ_INFO parameters defined in a
Shapefile
> *.prj:
>
> name: NAD_1983_HARN_StatePlane_Oregon_North_FIPS_3601_Feet_Intl
> datum: nad83harn
> ellps: grs80
> proj: lcc
> lat_1: 44.33333333333334
> lat_2: 46
> lat_0: 43.66666666666666
> lon_0: -120.5
> x_0: 2500000
> y_0: 0
> no_defs: defined
>
>
> The source location has these PROJ_INFO parameters defined in the
> metadata.xml with EPSG 2992:
>
> name: NAD83 / Oregon Lambert (ft)
> datum: nad83
> ellps: grs80
> proj: lcc
> lat_1: 43
> lat_2: 45.5
> lat_0: 41.75
> lon_0: -120.5
> x_0: 399999.9999984
> y_0: 0
> no_defs: defined
> nadgrids: WO
>
>   When I imported this OFGDB source and selected epsg 2992 a window with 6
> flavors appeared. I selected #6: Washington/Oregon HARM adjustment.

yes, it would apply
nadgrids=WO

according to the list in the location manager selection window (I just
tried here with EPSG 2992).

> Apparently this was not used.

I checked:
- in GRASS GIS 7.2 is is used, should be ok:

g.proj -p

-PROJ_INFO-------------------------------------------------
name       : NAD83 / Oregon Lambert (ft)
datum      : nad83
ellps      : grs80
proj       : lcc
lat_1      : 43
lat_2      : 45.5
lat_0      : 41.75
lon_0      : -120.5
x_0        : 399999.9999984
y_0        : 0
no_defs    : defined
nadgrids   : WO
-PROJ_EPSG-------------------------------------------------
epsg       : 2992
-PROJ_UNITS------------------------------------------------
unit       : foot
units      : feet
meters     : 0.3048

Question: do you use 7.2.svn?

- in trunk ("7.3") it is not used due to NAD file removal during the recent
code sprint upon long discussions with the GDAL maintainer Even Rouault (
https://trac.osgeo.org/grass/changeset/69211). Here it should use the
respective file through GDAL/PROJ4 since we don't want to keep our private
copies any longer.

>   From the target location/mapset I tried v.proj
> location=ODOT2014mapset=data_source.gdb input=state_roads_2014 (I renamed
> the long original name to this with g.rename.) and was told there
> was no projection conversion table available.

Sounds to me that you are using the trunk version of GRASS GIS?

>   Should I re-import the data and try to ensure that the HARM adjustment
is
> accepted, or is there a way of reprojecting the source to match the
target?

In the first place I would use GRASS GIS 7.2.svn since the NAD management
stuff in trunk is currently experimental.
It is a fairly complex beast. The idea is that GRASS no longer bothers
about NAD and just receives related info from GDAL/PROJ4. Seems not to be
complete yet (I'll update https://trac.osgeo.org/grass/ticket/2456
accordingly).

For now, here a cmd line way for GRASS GIS 7.2:

# create dummy location just in order to fetch the list
# of available datums for given EPSG code:
grass72 -c epsg:2992 ~/grassdata/dummy --exec g.proj -t epsg=2992
datumtrans=-1
Cleaning up temporary files...
Creating new GRASS GIS location/mapset...
Executing <g.proj -t datumtrans=-1 epsg=2992> ...
---
1
Used in whole nad83 region
towgs84=0.000,0.000,0.000
Default 3-Parameter Transformation (May not be optimum for older datums;
use this only if no more appropriate options are available.)
---
2
Used in Florida
nadgrids=FL
Transforms 'Old NAD83' to 'HPGN NAD83'
---
3
Used in Maryland
nadgrids=MD
Transforms 'Old NAD83' to 'HPGN NAD83'
---
4
Used in Tennessee
nadgrids=TN
Transforms 'Old NAD83' to 'HPGN NAD83'
---
5
Used in Wisconsin
nadgrids=WI
Transforms 'Old NAD83' to 'HPGN NAD83'
---
6
Used in Washington - Oregon
nadgrids=WO
Transforms 'Old NAD83' to 'HPGN NAD83'
Execution of <g.proj -t datumtrans=-1 epsg=2992> finished.
Cleaning up temporary files...

# now generate location using EPSG code and related datumtransform #6:
grass72 -c epsg:2992 ~/grassdata/oregon2992_nad83_WO --exec g.proj -t
epsg=2992 datumtrans=6 -p
Cleaning up temporary files...
Creating new GRASS GIS location/mapset...
Executing <g.proj -t epsg=2992 datumtrans=6 -p> ...
-PROJ_INFO-------------------------------------------------
name       : NAD83 / Oregon Lambert (ft)
datum      : nad83
ellps      : grs80
proj       : lcc
lat_1      : 43
lat_2      : 45.5
lat_0      : 41.75
lon_0      : -120.5
x_0        : 399999.9999984
y_0        : 0
no_defs    : defined
nadgrids   : WO
-PROJ_EPSG-------------------------------------------------
epsg       : 2992
-PROJ_UNITS------------------------------------------------
unit       : foot
units      : feet
meters     : 0.3048
Execution of <g.proj -t epsg=2992 datumtrans=6 -p> finished.
Cleaning up temporary files...

# eventually start using the new location
grass72 ~/grassdata/oregon2992_nad83_WO/PERMANENT/

But! When entering this location and running
g.proj -p
still nadgrids is not listed any more... confusing.
Anyone with more insights here?

Markus
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