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
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
On Thu, 2004-11-11 at 14:23, Paul Kelly wrote:
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.
I had not noticed that but when I setup of the location I entered the
following:
projection: stp
ellipsoid: grs80
datum: nad83
state FIPS code: 48
county FIPS code: 453
and then entered the default window
Hmmm... Maybe there was a problem there as when I recreate the location
it says:
-----------------------------------------------------------
PROJ_INFO file:
name: State Plane
datum: nad83
dx: 0.000000
dy: 0.000000
dz: 0.000000
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
-----------------------------------------------------------
Gonna try that v.proj again and see what happens.
Ed
On Thu, 11 Nov 2004, bfdi533 wrote:
> -----------------------------------------------------------
> 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
> -----------------------------------------------------------