Working with Elevations instead of Ellipsoid Heights

[Bow Tie Surveyor]

I am working on my first project with Photoscan Pro. I can see that I can change the horizontal datum and grid projection easy enough for the camera and marker positions (I'm working on NAD83(2011) datum with the Florida State Plane Coordinate System, East Zone in US feet). However, it appears that the program wants to use ellipsoid heights instead of the NAVD88 elevations that we typically work. I have downloaded the GEOID12B model to the geoid folder, but don't see how to tell the program to apply it. Can you help?

Thanks,

[Bow Tie Surveyor]

OK, I have made a stab at creating a custom PRJ file to get it to work.

Here is what I created:

COMPD_CS["NAD83(HARN) / Florida East (ftUS) + NAVD88 height",
PROJCS["NAD83(HARN) / Florida East (ftUS)",
GEOGCS["NAD83(HARN)",
DATUM["NAD83(HARN)",
SPHEROID["GRS 1980",6378137,298.257222101,AUTHORITY["EPSG","7019"]],
TOWGS84[0,0,0,0,0,0,0],AUTHORITY["EPSG","6152"]],
PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],
UNIT["degree",0.01745329251994328,AUTHORITY["EPSG","9102"]],
AUTHORITY["EPSG","4152"]],
PROJECTION["Transverse_Mercator",AUTHORITY["EPSG","9807"]],
PARAMETER["latitude_of_origin",24.33333333333333],
PARAMETER["central_meridian",-81],
PARAMETER["scale_factor",0.999941177],
PARAMETER["false_easting",656166.667],
PARAMETER["false_northing",0],
UNIT["US survey foot",0.3048006096012192,AUTHORITY["EPSG","9003"]],
AUTHORITY["EPSG","2881"]],
VERT_CS["navd88-12b geoid height",
VERT_DATUM["North American Vertical Datum 1988",2005,AUTHORITY["EPSG","5103"]],
UNIT["metre",1,AUTHORITY["EPSG","9001"]],AUTHORITY["EPSG","5703"]],
]

However, the program keeps giving me an error message stating "Unsupported Vertical Datum". Even the stock NAD(HARN) + NAVD88 Height that comes with AgiSoft Photoscan gives me the same message. I have all of the NAVD88 geoids downloaded into the geoids folder. I'm not sure what I am missing here. Any help is appreciated. Thanks,

[Alexey Pasumansky]

Hello Bow Tie Surveyor,

Undulation grids are defined on the certain datum, so the datum of the projected coordinate system should correspond to the datum on which geoid is defined.
If you cannot find proper geoid in our list, please specify the combination of geoid and datum it should be defined on.

[Robert Dzur]

Hello I would like to add to this thread as I believe I am running into a similar issue.

I have the latest 1.3.1.4030 build (OS X) installed with navd88-12b.tif in the geoids folder.

I have a project that is currently defined in WGS84 where cameras and markers are ellipsoidal heights in meters.

I would like to convert the project to orthometric (NAVD88 - 12B) heights.

Using the "Convert Reference" dialog I can load a custom user defined coordinate reference system for the project area (attached 2258_6360.prj), however, upon execution I receive an error message that the selected transformation is not supported.

Conversely I have also tried to Add Photos and load the reference orthometric (NAVD88 - 12B) heights for the camera positions using import csv with the same prj defined and I receive the same information that Mr. Bow Tie Surveyor receives -- "Unsupported Vertical Datum" and the console messages report -- "Error: Vertical Datum Missing".  Nonetheless the csv defined Easting, Northing and Altitude (ft) values still load in the Reference pane but no camera positions are visible in the model view and saving the project still reports the "Error: Vertical Datum Missing" message at the console.

I'm wondering how to set this up properly.  Thank you for your assistance.

Robert

[Alexey Pasumansky]

Hello Robert,

Geoid 12B published on our web-site is related to the undulation grid defined on NAD83(2011) datum (EPSG::6318), while in your PRJ file you seem to be using NAD83 (EPSG::4269).

I think you need to create the custom PRJ basing on the EPSG::6529 system. Here - http://www.agisoft.com/forum/index.php?topic=6827.msg32951#msg32951 I have specified the steps, how such custom coordinate system can be created in PhotoScan 1.3.

[bortoman]

This is interesting!
would it be possible to load a local geoid (ASCII Geoid Height Grid File) somehow?

Since all the survey of the markers is done based on that geoid large areas would give better results right?

[Robert Dzur]

Hi Alexey,

To follow-up, the link you provided to the recommended workflow worked fine.  I did have some issues with a second node recognizing the geoid grid, and I may not have opened and closed the application properly so I still need to do some further evaluation over the network, however, on one node the prj definition is now acceptable for use with the geoid 12B.  Thanks again for your assistance.

Robert
 

[gto234]

Hi,
I work with Orthometric Heights and use a local GEOID in my GPS measurements.
However I cannot set Photoscan to work with some geoid. It pop's that the selected vertical system is not supported.
I want to ask, is it ok to select the projection which uses ellipsoid heights and the GCP's I measure is on orthometric heights?
Will it have big difference in the final result? The areas i usually work is about 10ha.

[Alexey Pasumansky]

Hello gto234,

Can you please specify which horizontal and vertical coordinate system you are using?

[gto234]

I work in GGRS87 (EPSG:2100) and try to combine it with a local geoid which is a Carlson .gsf file.
But it could combined also with EGM96 or EGM08 but neither work and prompts that they are not supported.
I have downloaded the files in geoid folder and I edit the original GGRS87 projection using the above geoids but i doesn't work.
Am I doing something wrong?