Datum selection & conversion

[TXPE]

I used to do everything in WGS84, but now working with survey companies, I have to deliver orthos and DEMs in one of the following datums (depending on project location):

Horizontal Datums used:
2916 (or 2275)  NAD83(HARN) - Texas North, US Survey Ft
2917 (or 2276)  NAD83(HARN) - Texas North Central, US Survey Ft
2918 (or 2277)  NAD83(HARN) - Texas Central, US Survey Ft
2919 (or 2278)  NAD83(HARN) - Texas South Central, US Survey Ft
2920 (or 2279)  NAD83(HARN) - Texas South, US Survey Ft

Vertical Datum
5703 NADV88

My GCPs and CPs are recorded in the above datums, whereas my photos are geotagged in WGS84.  My plan is to convert the photo geotags to match GCPs.  I then would not have to do any transformations later.

I'm a little, or lot, confused on the conversion feature in Photoscan.  When converting, one must know and set the source and target datums.  Which is which in Photoscan?  I can see the datum in Reference Settings and a datum in the Convert Reference screen.  If photo geotags are WGS84 and I want to convert to one of the above datums, what do I set these to?

Next…
I see the 5 horizontal datums as options.  I also see NAD83+NAVD88 (5498) and NAD83(2011)+NAVD88 (6349).  Is it possible to combine NAVD88 with the above horizontal datums? If so, how do you do this?

Alternative solution:
Use NOAA Vdatum program to convert photo geotags.  Though this would not address the datum assignment in Photoscan.

Thanks,
Doug

[Paulo]

Doug,

try this proj for Texas Central.... In the projection it supposes that the transform from NAD93(HARN) to WGS84 is 0,0,0,0,0,0,0

For other projections in Texas, just replace parameters for Projected CS accordingly...

Hope it works,

[TXPE]

Thanks for the detailed response.  I don't think I've seen such a long .prj file contents.   

Now, I just have to figure out how to make use of it.