On 20/10/15 19:08, Uttam Kumar wrote:
I have been trying for a long time. Something wrong is going on. I
appreciate if you can correct me.
I have all my source images in sinusoidal projection in a location
called "Landsat_sinu".
My target locatoin is "Landsat_laea" I tried using the default option in
GRASS GUI as follows:
1.) *Select coordinate system parameters from a list*
2.) Projection code: *laea*
3.) Datum with associated ellipsoid:
Central parallel: *30*
Central Meridian: *-96*
False easting: *0*
False northing: *0*
4.) Datum code: *nad83*
5.) Select from the list of datum transformation: *1 used in whole nad83
region*
+proj=laea
+lat_0=30
+lon_0=-96
+x_0=0
+y_0=0
+no_defs
+a=6378137
+rf=298.257222101
+towgs84=0.000,0.000,0.000
to_meter=1
+datum=nad83
Finish.
Is everything ok with this for the below (required) target definition?
**PROJ.4 : '+proj=laea +lat_0=30 +lon_0=-96 +x_0=0 +y_0=0 +datum=NAD83
+units=m +no_defs '**
Looks like at some point I am making a small mistake. I must get this as
the projected coordinates.
*north=1064601.38274499
south=830176.771464028
east=-1960125.15283348
west=-2265106.68066176*
And what is wrong with these coordinates ? Those are exactly the ones I
get and they are very close to the ones you got from ENVI:
> > Upper Left (-2265106.681W, 1064601.383N)
> > Lower Left (-2265106.681W, 830181.383N)
> > Upper Right (-1960126.681W, 1064601.383N)
> > Lower Right (-1960126.681W, 830181.383N)
i.e. 4.6m difference for South and 1.5m difference for East. You would
have to check how the NAD83 conversion is done exactly to see if the
difference could come from there.
Moritz
Any help is appreciated.
Uttam.
On Wed, Oct 14, 2015 at 4:52 PM, Moritz Lennert
<mlenn...@club.worldonline.be <mailto:mlenn...@club.worldonline.be>> wrote:
[Please keep conversations on the list]
On 14/10/15 23:19, Uttam Kumar wrote:
_
_
_*This information is for the original data (Source):*_
*PROJ.4 : '+proj=sinu +lon_0=0 +x_0=0 +y_0=0 +a=6371007.181
+b=6371007.181 +units=m +no_defs '*
Coordinate System is:
PROJCS["Sinusoidal",
GEOGCS["GCS_Unknown",
DATUM["Unknown",
SPHEROID["S_Unknown",6371007.181,0.0]],
PRIMEM["Greenwich",0.0],
UNIT["Degree",0.0174532925199433]],
PROJECTION["Sinusoidal"],
PARAMETER["False_Easting",0.0],
PARAMETER["False_Northing",0.0],
PARAMETER["longitude_of_center",0.0],
UNIT["Meter",1]]
Origin = (-10801805.197699999436736,4130102.079069999977946)
Pixel Size = (30.000000000000000,-30.000000000000000)
*
_This information is for the destination data (Target):_*
*PROJ.4 : '+proj=laea +lat_0=30 +lon_0=-96 +x_0=0 +y_0=0
+datum=NAD83
+units=m +no_defs '*
In your first mail you said:
Lambert Azimuthal Equal Area, Datum: WGS84
but here the datum is NAD83.
Using your projection info, I get almost exactly the same results in
GRASS as you report from ENVI:
On 08/10/15 21:36, Uttam Kumar wrote:> Reprojected in ENVI (Lambert
Azimuthal Equal Area, Datum: WGS84)
> -------------------------------------------------------------------------
> Corner Coordinates:
>
> Upper Left (-2265106.681W, 1064601.383N)
> Lower Left (-2265106.681W, 830181.383N)
> Upper Right (-1960126.681W, 1064601.383N)
> Lower Right (-1960126.681W, 830181.383N)
GRASS 7.0.1 (test_LAEA):~ > v.info <http://v.info> -g Image_Boundary_box
north=1064601.38274499
south=830176.771464028
east=-1960125.15283348
west=-2265106.68066176
Don't have the time now to explore the exact differences, but either
it's a question of definition of the bounding box, or it possibly be
a question of which specific NAD83 transformation parameters were used.
Moritz
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