[GRASS-user] r.proj issue

[Helmut Kudrnovsky]

Rich Shepard wrote
> Reprojecting a 10m DEM fails. Following are the command and input/output
> projection and map description information. Screenshots of the input and
> output maps are attached.
> 
> I need to understand why the output is wrong.
> 
> Command:
> r.proj loc=Oregon map=topography in=n46w123 met=lanczos_f mem=16000 --o
> 
> Input location:
> name: unnamed
> ellps: grs80
> proj: lcc
> lat_1: 46
> lat_2: 44.33333333333334
> lat_0: 43.66666666666666
> lon_0: -120.5
> x_0: 2500000
> y_0: 0
> no_defs: defined
> unit: Meter
> units: Meters
> meters: 1
> 
> Cols: 502 (80961)
> Rows: 39234 (113148)
> North: 262349.035904 (262349.035904)
> South: 223115.062541 (149201.112724)
> West: 2302891.866970 (2302891.866970)
> East: 2303393.867032 (2383852.876897)
> EW-res: 1.000000
> NS-res: 0.999999
> 
> Output location:
> name: NAD83(HARN) / Oregon North
> datum: nad83harn
> ellps: grs80
> proj: lcc
> lat_1: 46
> lat_2: 44.33333333333334
> lat_0: 43.66666666666666
> lon_0: -120.5
> x_0: 2500000
> y_0: 0
> no_defs: defined
> unit: meter
> units: meters
> meters: 1
> 
> Cols: 500 (71702)
> Rows: 39232 (50757)
> North: 262348.951018 (273873.984569)
> South: 223116.836808 (223116.836808)
> West: 2302892.017711 (2231689.553588)
> East: 2303392.020970 (2303392.020970)
> EW-res: 1.000007
> NS-res: 1.000003Cols: 500 (71702)
> Rows: 39232 (50757)
> North: 262348.951018 (273873.984569)
> South: 223116.836808 (223116.836808)
> West: 2302892.017711 (2231689.553588)
> East: 2303392.020970 (2303392.020970)
> EW-res: 1.000007
> NS-res: 1.000003
> 
> Rich
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> 
> input-dem.png (296K)
> <http://osgeo-org.1560.x6.nabble.com/attachment/5416106/0/input-dem.png>
> output-dem.png (28K)
> <http://osgeo-org.1560.x6.nabble.com/attachment/5416106/1/output-dem.png>

a good thing to see if reprojection of raster data works correctly, is
comparing before/after r.proj with gdalwarp (1) results. 

(1) https://gdal.org/programs/gdalwarp.html#gdalwarp




-----
best regards
Helmut
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