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Author Topic: EGM2008 geoid reprojected to ETRS89  (Read 2691 times)

Isaac H. E.

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EGM2008 geoid reprojected to ETRS89
« on: February 23, 2018, 03:11:44 AM »
Hi,


I would like to use a croped, reprojected and vertically shifted version of the EGM2008 (defined for WGS84) geoid with the ETRS89 datum, is there any special instructions I should use to create a valid tiff file to be placed in PS geoids directory?


Many thanks


Isaac

ruyi7952

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Re: EGM2008 geoid reprojected to ETRS89
« Reply #1 on: February 23, 2018, 09:48:28 AM »
https://www.novatel.com/support/known-solutions/wgs84-to-etrs89-datum-transformations/

EGM2008 is the height anomaly data.etrs89 is datum,You can convert WGS84 to etrs89 directly using mathematical methods, or use control points for conversion.
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Isaac H. E.

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Re: EGM2008 geoid reprojected to ETRS89
« Reply #2 on: February 23, 2018, 12:44:14 PM »
Hello ruyi7952,


I'm the author of that article at NovAtel.com, my problem has nothing to do with datum conversions, my question is about the resulting TIFF file that PS will use from geoids folder, shall the TIFF file have some sort of specific format? I can see that in the egm2008-1.tif file the EXIF specifies VERT_DATUM["EGM2008 geoid",2005,AUTHORITY["EPSG","1027"]] in the ImageDescription field, is all what it takes to use a TIFF withi PS?


Thanks


Isaac

Isaac H. E.

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Re: EGM2008 geoid reprojected to ETRS89
« Reply #3 on: February 23, 2018, 02:24:38 PM »
Hi,


The following Dropbox link points at the folder were I have the geoid prepared:
https://www.dropbox.com/sh/wb22ryi4068f2st/AABQaMOPjYlbA0jLaI6T7h_ba?dl=0

It is a subset of the egm2008-1.tif just covering Catalunya and shifted +0.5951 metres upwards.

The Authority is ICGC (Institut Cartogràfic i Geològic de Catalunya)

The current metadata:

Code: [Select]

DESCRIPTION=EGM2008-1+0_5951_Catalunya_WGS84.tif
UPPER LEFT X=0.0452233333
UPPER LEFT Y=42.9100696667
LOWER RIGHT X=3.4118899711
LOWER RIGHT Y=40.4934030208
WEST LONGITUDE=0° 02' 42.8040" E
NORTH LATITUDE=42° 54' 36.2508" N
EAST LONGITUDE=3° 24' 42.8039" E
SOUTH LATITUDE=40° 29' 36.2509" N
UL CORNER LONGITUDE=0° 02' 42.8040" E
UL CORNER LATITUDE=42° 54' 36.2508" N
UR CORNER LONGITUDE=3° 24' 42.8039" E
UR CORNER LATITUDE=42° 54' 36.2508" N
LR CORNER LONGITUDE=3° 24' 42.8039" E
LR CORNER LATITUDE=40° 29' 36.2509" N
LL CORNER LONGITUDE=0° 02' 42.8040" E
LL CORNER LATITUDE=40° 29' 36.2509" N
PROJ_DESC=Geographic (Latitude/Longitude) / WGS84 / arc degrees
PROJ_DATUM=WGS84
PROJ_UNITS=arc degrees
EPSG_CODE=EPSG:4326
COVERED AREA=75149 sq km
GDAL_NO_DATA_VALUE=-32767
NUM COLUMNS=203
NUM ROWS=146
NUM BANDS=1
PIXEL WIDTH=0.01667 arc degrees
PIXEL HEIGHT=0.01667 arc degrees
MIN ELEVATION=47.612 meters
MAX ELEVATION=55.123 meters
ELEVATION UNITS=meters
BIT DEPTH=32
SAMPLE TYPE=32-bit Floating Point
GT_CITATION=GCS_WGS_1984
PHOTOMETRIC=Greyscale (Min is Black)
BIT_DEPTH=32
SAMPLE_FORMAT=Floating Point
ROWS_PER_STRIP=1
COMPRESSION=LZW
ORIENTATION=row 0 top, col 0 lhs
PIXEL_SCALE=( 0.0166666665238, 0.0166666665238, 1 )
TIEPOINTS=( 0.00, 0.00, 0.00 ) --> ( 0.0452233333, 42.9100696667, 0.0000000000 )
MODEL_TYPE=Geographic lat-long system
RASTER_TYPE=Pixel is Point
VERT_DATUM=None Specified


Before creating the PS geoid it should be transformed from WGS84 to ETRS89 datum.


Thanks


Isaac

Isaac H. E.

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Re: EGM2008 geoid reprojected to ETRS89
« Reply #4 on: February 24, 2018, 01:48:45 AM »
Hi,


Nevermind, I already found the way of creating my own geoids, case closed.


Best regards.


Isaac