GM 10 rendering Arc/Info Binary Grids with non-square pixels

[ccrosby]

Hello - I've just encountered a new error with GM v. 10.02 that I've never seen before.

I have a series of Arc/Info binary grids (1m lidar data) that I'm loading into GM for export to Google Earth KMZ. The grids load fine but one appears to be "stretched" in the north-south direction. In the following image the actual extent of the data is the black outline - note how the data matches well at the north end where is abuts the next grid north, but as you move south the alignment gets worse and worse:



Global Mapper Metadata for the file shows that it is reading the grid as if the pixels are not square (1 x 1.059 m vs. 1 x 1 m - see bold text in paste of GM metadata output):

FILENAME=E:\GeoEarthScope\SoCal_GeoES_LiDAR\Mosaic s\SoCal_Panamint_filtered_arcinfo_mosaics\mosaic_1 m_new\fm477_487\w001001.adf
DESCRIPTION=fm477_487 GRID (w001001.adf)
UPPER LEFT X=477000.500
UPPER LEFT Y=4014999.470
LOWER RIGHT X=486999.500
LOWER RIGHT Y=3960000.530
WEST LONGITUDE=117° 15' 21.9426" W
NORTH LATITUDE=36° 16' 47.4963" N
EAST LONGITUDE=117° 08' 37.8749" W
SOUTH LATITUDE=35° 47' 1.7292" N
PROJ_DESC=UTM Zone 11 / WGS84 / meters
PROJ_DATUM=WGS84
PROJ_UNITS=meters
EPSG_CODE=32611
COVERED AREA=212.3 sq mi
NUM COLUMNS=10000
NUM ROWS=51928
PIXEL WIDTH=1 meters
PIXEL HEIGHT=1.059 meters
MIN ELEVATION=281.615 meters
MAX ELEVATION=1160.29 meters
ELEVATION UNITS=meters
BIT_DEPTH=24

For comparison, the next grid to the north shows the following in GM Metadata:

FILENAME=E:\GeoEarthScope\SoCal_GeoES_LiDAR\Mosaic s\SoCal_Panamint_filtered_arcinfo_mosaics\mosaic_1 m_new\fm467_477\w001001.adf
DESCRIPTION=fm467_477 GRID (w001001.adf)
UPPER LEFT X=467000.500
UPPER LEFT Y=4026999.500
LOWER RIGHT X=476999.500
LOWER RIGHT Y=4006000.500
WEST LONGITUDE=117° 22' 4.6198" W
NORTH LATITUDE=36° 23' 16.2885" N
EAST LONGITUDE=117° 15' 21.0305" W
SOUTH LATITUDE=36° 11' 53.7140" N
PROJ_DESC=UTM Zone 11 / WGS84 / meters
PROJ_DATUM=WGS84
PROJ_UNITS=meters
EPSG_CODE=32611
COVERED AREA=81.07 sq mi
NUM COLUMNS=10000
NUM ROWS=21000
PIXEL WIDTH=1 meters
PIXEL HEIGHT=1 meters
MIN ELEVATION=513.3 meters
MAX ELEVATION=1155.381 meters
ELEVATION UNITS=meters
BIT_DEPTH=24

If I take the same grid and load it into ArcGIS this problem doesn't occur and Arc shows the grid as having pixel dimensions of 1x1 meters. GDALInfo also reads the file as having 1x1 m pixels:

Driver: AIG/Arc/Info Binary Grid
Files: fm477_487copy
fm477_487copy.aux
fm477_487copy.rrd
fm477_487copy\dblbnd.adf
fm477_487copy\hdr.adf
fm477_487copy\log
fm477_487copy\metadata.xml
fm477_487copy\prj.adf
fm477_487copy\sta.adf
fm477_487copy\w001000.adf
fm477_487copy\w001000x.adf
fm477_487copy\w001001.adf
fm477_487copy\w001001x.adf
Size is 10000, 55000
Coordinate System is:
PROJCS["UTM Zone 11, Northern Hemisphere",
GEOGCS["WGS 84",
DATUM["WGS_1984",
SPHEROID["WGS 84",6378137,298.257223563,
AUTHORITY["EPSG","7030"]],
TOWGS84[0,0,0,0,0,0,0],
AUTHORITY["EPSG","6326"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.0174532925199433,
AUTHORITY["EPSG","9108"]],
AUTHORITY["EPSG","4326"]],
PROJECTION["Transverse_Mercator"],
PARAMETER["latitude_of_origin",0],
PARAMETER["central_meridian",-117],
PARAMETER["scale_factor",0.9996],
PARAMETER["false_easting",500000],
PARAMETER["false_northing",0],
UNIT["METERS",1]]
Origin = (477000.000000000000000,4015000.000000000000000)
Pixel Size = (1.000000000000000,-1.000000000000000)
Corner Coordinates:
Upper Left ( 477000.000, 4015000.000) (117d15'21.96"W, 36d16'46.84"N)
Lower Left ( 477000.000, 3960000.000) (117d15'16.20"W, 35d47'1.71"N)
Upper Right ( 487000.000, 4015000.000) (117d 8'41.11"W, 36d16'47.51"N)
Lower Right ( 487000.000, 3960000.000) (117d 8'37.85"W, 35d47'2.37"N)
Center ( 482000.000, 3987500.000) (117d11'59.27"W, 36d 1'54.67"N)
Band 1 Block=256x4 Type=Float32, ColorInterp=Undefined
Min=281.615 Max=1160.290
NoData Value=-3.4028234663852886e+038
Overviews: 2500x13750, 1250x6875, 625x3438, 313x1719, 157x860, 79x430, 40x215
Metadata:
LAYER_TYPE=athematic

Thoughts? I tried redefining the projection in Arc and that didn't work. I use GM regularly and have never seen this before.

Thanks in advance.

-Chris

[global_mapper]

Chris,

There were recently some changes to the reading of Arc Binary Grid files to allow loading very large Arc Binary Grids. The symptoms of the problem that were fixed included a stretch in the north/south direction. Can you try downloading and installing the v11.01 trial from http://www.globalmapper.com/global_mapper11_setup.exe and see if that fixes the issue?

Thanks,

Mike
Global Mapper Support
support@globalmapper.com

[ccrosby]

Thanks for the reply. Makes sense that the issue is file size related given that that specific grid is ~2.1 GB.

I just downloaded and installed the trial of GM11 and the files loads correctly. Thanks.

-cc