[GRASS-user] Something wrong: Reprojection of raster maps in various platforms: projected coordinates are different

[Uttam Kumar]

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*


Any help is appreciated.

Uttam.


On Wed, Oct 14, 2015 at 4:52 PM, Moritz Lennert <
mlennert at 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 -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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