Defining Projected coordinate system with EGM2008 geoid

[Paulo]

Hello.

I am trying to define a projected coordinate sytem (UTM 14 on WGS84 datum) combined with EGM2008 geoid so as to correct  altitude with geoid height. See attaced prj file wgs84 UTM14N+EGM2008.prj. When I try to load this prj in Photoscan Coordinate System. I get : 'Can't load coordinate system' error.

However, i can load a combined geographic coordinate system with EGM2008 geoid without any error. See attaced prj file WGS84+EGM2008.prj.

There seems to be a problem in defining custom projected coordinate systems with geoid files.

Note that I have a geoid file egm2008-2.5.tif present in geoids folder of PhotoScan pro installation directory.

Any help on this?

[Alexey Pasumansky]

Hello pap1956,

It looks like you have one missing closing bracket in your definition for DATUM section. Please try the following PRJ file:

Code: [Select]

COMPD_CS["WGS 84 / UTM zone 14N +  EGM2008 geoid height",
PROJCS["WGS 84 / UTM zone 14N",
GEOGCS["WGS 84",
DATUM["World Geodetic System 1984",
SPHEROID["WGS 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]]]
PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],
UNIT["degree",0.01745329251994328,AUTHORITY["EPSG","9102"]],
AUTHORITY["EPSG","4326"]],
PROJECTION["Transverse_Mercator",AUTHORITY["EPSG","9807"]],
PARAMETER["latitude_of_origin",0],
PARAMETER["central_meridian",-99],
PARAMETER["scale_factor",0.9996],
PARAMETER["false_easting",500000],
PARAMETER["false_northing",0],
UNIT["metre",1,AUTHORITY["EPSG","9001"]],
AUTHORITY["EPSG","32614"]],
VERT_CS["EGM2008 geoid height",
VERT_DATUM["EGM2008  geoid",2005,AUTHORITY["EPSG","1027"]],
UNIT["metre",1,AUTHORITY["EPSG","9001"]],
AUTHORITY["EPSG","3855"]]]

[Paulo]

Thank you , Alexey.

It works fine.

[Seboon]

Hello,

I have the same problem for UTM 36N with EGM 2008 ; following your example, I've tried to make the prj file (atached below).
When running Photoscan for the MNT of my area, it crashes or make a wrong MNT
My GCP were tooken with a GPS configured with WGS 84 UTM 36N and  EGM2008, in order to obtain the "wright" coordinates and elevations directly. And that's these elevations I entered for the GCP (attached also). Maybe it's part of the problem? Or my code is completely wrong? :-)
Thanks for your help!

[Alexey Pasumansky]

Hello Seboon,

Can you please provide the screenshot of the source values for the reference pane?

[Seboon]

Oops sorry, loaded twice the same folder!

Here comes the good one!

Tanks!

[Alexey Pasumansky]

Are you sure that Easting for the point 2 is correct and it's two km off the other points?

[Paulo]

Thinking there  may be a typing error in Est coordinate of point 2....

3931... instead of 3913....

[Seboon]

I'm so foolish!!
It was this mistake,  and it works perfectly now!
Sorry for wasting your time...
Thanks

[Seboon]

Hi,

I come back to you just to know if could provide me the prj file for EGM 2008 1'?
It's been now two hours I try to get it on web, but unable to find it.
Thanks a loy for what you can do!!

[Paulo]

Hello,

if you want to use UTM zone 36/WGS84 along with EGM2008 geoid vertical datum, then the prj file you attached previously will work fine as long as you have downloaded the egm2008-2.5.tif file inside the C:\Program Files\Agisoft\PhotoScan Pro\geoids folder....

Regards,

[Seboon]

Thank for your response pap,

Yeah I know it works  with egm 2005 -2.5, I've already tested it.
But I would to do the same operation with EGM - 1', as my points were directly  tooken with this geoid grid (EGM 2008-1 inside my GPS)...

I may just need the prj file for the EGM 2008-1, but hard to find!

[Paulo]

I see,

maybe check that it is completely downloaded (896 MB) as I tried to download the egm2008 1 ' file twice and it did not completely do it....

Any way, can always use the 2.5 ' file, it is just  less dense but results would be about the same...