[GRASS-user] more on misaligned rasters vs vectors

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: |
| |
+----------------------------------------------------------------------------+

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@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: |
| |
+----------------------------------------------------------------------------+

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Kirk wrote:

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.

try looking at the raster .img with 'gdalinfo'.
Along with a bunch of other stuff it should report
the 4 corners of the map in both AEA units and
lat/lon. Do the lat/lons of the corners look ok there?

You can also try converting some test points with
PROJ.4's cs2cs. (see the m.proj module for hints
on the terms to use)

'd.grid -g' is another nice sanity-check experiment
to see which dataset is right, and which is wrong.

Hamish