[GRASSLIST:4785] Re: trouble with v.proj

[Paul Kelly]

Your second location has no datum information. I presume it is not in 
wgs84 thus you need to specify a datum or the transformation will not be 
accurate. If it is in NAD27, you could just add the line
nadgrids: conus
to the PROJ_INFO file and try again.


On Thu, 11 Nov 2004, bfdi533 wrote:

> I have a TIGER line file that was imported into a LL location with an
> output from g.projinfo here:
>
> -----------------------------------------------------------
> PROJ_INFO file:
> name:    Latitude-Longitude
> datum:   wgs84
> dx:      0.000000
> dy:      0.000000
> dz:      0.000000
> proj:    ll
> ellps:   wgs84
> -----------------------------------------------------------
> PROJ_UNITS file:
> unit:    degree
> units:   degrees
> meters:  1.0
> -----------------------------------------------------------
>
> I then input another roads file into a location in TX State Plane format
> with output from g.projinfo here:
>
> -----------------------------------------------------------
> PROJ_INFO file:
> name:    State Plane
> proj:    lcc
> a:       0.63782064e+07
> es:      0.6768657997291094e-02
> x_0:     0.6096012192024384e+06
> y_0:     0
> lon_0:   100d20'w
> lat_0:   29d40'n
> lat_1:   31d53'n
> lat_2:   30d7'n
> -----------------------------------------------------------
> PROJ_UNITS file:
> unit:    meter
> units:   meters
> meters:  1.0
> -----------------------------------------------------------
>
> I then tried v.proj from the LL location INTO the State Plane location
> and did a d.vect on both sets of roads.  They do not line up.
>
> Here is the region from the STP imported vector file:
>
> GRASS:~ > g.region vect=streetcl
> GRASS:~ > d.erase
> GRASS:~ > g.region -l
> long: 48.34520 lat: 86.33708 (north/west corner)
> long: 51.00098 lat: 85.50330 (north/east corner)
> long: 41.70189 lat: 85.31135 (south/east corner)
> long: 38.11301 lat: 86.14387 (south/west corner)
> rows:       512
> cols:       514
> Center Longitude: 44:47:24.969634E [44.79027]
> Center latitude:  85:49:26.046164N [85.82390]
>
> And here is the region that I get from running the same commands on the
> vector file that was imported with v.proj:
> GRASS:~ > g.region vect=tx_travis
> GRASS:~ > d.erase
> GRASS:~ > g.region -l
> long: -98.17640 lat: 30.64542 (north/west corner)
> long: -97.35039 lat: 30.62892 (north/east corner)
> long: -97.36951 lat: 30.00828 (south/east corner)
> long: -98.19023 lat: 30.02468 (south/west corner)
> rows:       150
> cols:       147
> Center Longitude: 97:46:17.870455W [-97.77163]
> Center latitude:  30:19:36.571973N [30.32683]
>
> It seems quite likely that I have something wrong with the STP location
> but I have recreated it more than once using the right info and then
> imported data (arcinfo shape files) that say they are in the STP coords
> that I created.  But, the above just does not line up right and the
> coords look to be correct for the projected vector file, actually.
>
> Any ideas on what I am doing wrong?
>
> Ed
>
>