Agisoft Metashape

Agisoft Metashape => General => Topic started by: PROBERT1968 on February 19, 2020, 05:56:46 PM

Title: WGS 1984 Geoid Question ?
Post by: PROBERT1968 on February 19, 2020, 05:56:46 PM

Does Metashape comes with WGS 1984 Geoid for the Vertical Datum and Vertical Coordinate System  (WKID 105700) ?

SO whenever I export any markers or shapefiles,  and when I open them in ArcMap 10.5.1 or ArcGIS Pro, I can see they are actually up in height rather at the ground.  I had to manual to set them to the ground.

Title: Re: WGS 1984 Geoid Question ?
Post by: Alexey Pasumansky on February 19, 2020, 06:13:23 PM

Hello PROBERT1968,

The heights of the model are estimated in accordance to the reference data used, considering the coordinate system selected in the Reference pane settings dialog. By default the altitude is estimated from the ellipsoid, unless compound coordinate system (with different vertical datum) is used.

Title: Re: WGS 1984 Geoid Question ?
Post by: PROBERT1968 on February 19, 2020, 06:38:17 PM

So are you saying that I have to manual it in the Reference settings to do that , correct ?

Title: Re: WGS 1984 Geoid Question ?
Post by: Alexey Pasumansky on February 19, 2020, 06:44:09 PM

If the reference data uses geoid as a base for Z estimation, you need to use compound coordinate system that uses the given geoid (the file with the undulation grid for such geoid would be also required, unless you use fixed offset from ellipsoid to geoid).

Title: Re: WGS 1984 Geoid Question ?
Post by: PROBERT1968 on February 19, 2020, 07:30:29 PM

Ok,  the reason I am asking is because I understand that when people use their drones and it comes with lat, long, altitude etc...

Problem is that I am working on many old aerial photos that do not come from drones...  it was from scanned digital files....

So that is the reason  I need the altitude numbers to input in the Reference pane

otherwise if you have any recommend, I'd be happy to hear from you....

Thank you.

Title: Re: WGS 1984 Geoid Question ?
Post by: Alexey Pasumansky on February 19, 2020, 10:00:30 PM

Hello PROBERT1968,

You can use some approximate altitude values and set low Z accuracy for camera locations. But use additional ground reference points with more accurate Z information.