[GRASS-user] more on misaligned rasters vs vectors
Maris Nartiss
maris.gis at gmail.com
Thu Nov 17 02:45:38 EST 2011
Hello,
as v.in.ogr and r.in.gdal are using GDAL/OGR library for data import,
the first step would be to compare gdalinfo and ogrinfo -ro -so
outputs for all datasets. Just execute: gdalinfo mydata.img and
ogrinfo -ro -so myshapefile.shp myshapefile
If You can't spot anything fishy, add output of those commands to this thread.
In Latvia I have seen enough datasets claiming to be LKS-92 (the
official country coordinate system) to contain data in Baltic-93
coordinate system and vice versa. Aren't there some similar coordinate
systems that could have been used for data with wrong metadata?
Maris.
2011/11/17 Kirk Wythers <kirk.wythers at gmail.com>:
> First a quick recap on the problem including suggestions from list.
>
> Problem:
>
> I imported three files (two shape files with v.in.ogr, and one .img file with r.in.gdal). All files purport to be alberrsequalarea projections and come from independent sources. Also, after reading the metadata for each file, the projections and geographic information appears identical for each file.
>
> All files were imported into an albers locatiog.region and while the two shape files appear correct (are properly aligned), while the raster (the .img) is shifted approximately 1600 km north. I checked the info for false northing on each file and they all report 0.000000 for false northing.
>
> Here is the kicker... a colleague imported the same files into ArcMap, and all three appear correct. His take was that maybe grass is reading the metadata for the .img file in an odd way... my take is that I'm probably doing something wrong. Or perhaps ArcMap is ignoring something that r.in.gdal is reading.
>
> Below I have included the output from g.proj, g.region, r.info and v.info (maybe some one can see something I am missing). Any ideas as to what else I should check would be appreciated.
>
> Thanks for help
>
>
>
> GRASS 6.4.1 (northcentralus_albersequalarea):~ > g.proj -p
> -PROJ_INFO-------------------------------------------------
> name : Albers Equal Area
> proj : aea
> datum : nad83
> ellps : grs80
> lat_1 : 29.5
> lat_2 : 45.5
> lat_0 : 23
> lon_0 : -96
> x_0 : 0
> y_0 : 0
> no_defs : defined
> -PROJ_UNITS------------------------------------------------
> unit : meters
> units : meterss
> meters : 1
> GRASS 6.4.1 (northcentralus_albersequalarea):~ > g.region -p
> projection: 99 (Albers Equal Area)
> zone: 0
> datum: nad83
> ellipsoid: grs80
> north: 2960848
> south: 2087348
> west: -122110
> east: 1141890
> nsres: 250
> ewres: 250
> rows: 3494
> cols: 5056
> cells: 17665664
>
> r.info and v.info for each file give:
>
> GRASS 6.4.1 (northcentralus_albersequalarea):~ > r.info mnwimifnfftgk7wt175v3_250m
> +----------------------------------------------------------------------------+
> | Layer: mnwimifnfftgk7wt175v3_250m Date: Fri Oct 14 11:10:29 2011 |
> | Mapset: lake_states Login of Creator: kirkw |
> | Location: northcentralus_albersequalarea |
> | DataBase: /Volumes/disk1/home1/kirkw/grassdata |
> | Title: ( mnwimifnfftgk7wt175v3 ) |
> | Timestamp: none |
> |----------------------------------------------------------------------------|
> | |
> | Type of Map: raster Number of Categories: 999 |
> | Data Type: CELL |
> | Rows: 3494 |
> | Columns: 5056 |
> | Total Cells: 17665664 |
> | Projection: Albers Equal Area |
> | N: 2960848 S: 2087348 Res: 250 |
> | E: 1141890 W: -122110 Res: 250 |
> | Range of data: min = 0 max = 999 |
> | |
> | Data Description: |
> | generated by r.in.gdal |
> | |
> | Comments: |
> | r.in.gdal input="/Volumes/disk1/home1/kirkw/Desktop/mnwimifnfftgk7wt\ |
> | 175v3.img" output="mnwimifnfftgk7wt175v3" |
> | |
> +----------------------------------------------------------------------------+
>
>
> GRASS 6.4.1 (northcentralus_albersequalarea):~ > v.info nw212
> +----------------------------------------------------------------------------+
> | Layer: nw212 |
> | Mapset: lake_states |
> | Location: northcentralus_albersequalarea |
> | Database: /Volumes/disk1/home1/kirkw/grassdata |
> | Title: |
> | Map scale: 1:1 |
> | Map format: native |
> | Name of creator: kirkw |
> | Organization: |
> | Source date: Tue Nov 15 08:14:37 2011 |
> |----------------------------------------------------------------------------|
> | Type of Map: vector (level: 2) |
> | |
> | Number of points: 0 Number of areas: 13 |
> | Number of lines: 0 Number of islands: 5 |
> | Number of boundaries: 20 Number of faces: 0 |
> | Number of centroids: 7 Number of kernels: 0 |
> | |
> | Map is 3D: No |
> | Number of dblinks: 1 |
> | |
> | Projection: Albers Equal Area |
> | N: 1322833.8573 S: 647305.3646 |
> | E: 1003361.9406 W: 6150.4319 |
> | |
> | Digitization threshold: 0 |
> | Comments: |
> | |
> +----------------------------------------------------------------------------+
>
>
>
> _______________________________________________
> grass-user mailing list
> grass-user at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/grass-user
>
More information about the grass-user
mailing list