Custom Projection - Help Needed

[Jeremiah_ROWE]

Can anyone here help me regarding the creation of a custom projection (.PRJ) file?

Horizontal: NAD83 (2011) US - Michigan - State Plane South (Zone 2113) - International Feet
Vertical: NAVD88

I don't have a copy of ArcGIS, otherwise this would be a lot easier.

Any help is greatly appreciated!

[Alexey Pasumansky]

Hello Jeremiah_ROWE,

If you are using version 1.3 you can follow these step:
- download Geoid 12A or Geoid 12B (depending on your needs) from this page - http://www.agisoft.com/downloads/geoids/ and put it to the /geoids/ folder in PhotoScan Pro installation directory;
- start PhotoScan and open project;
- open Reference pane settings dialog and click More in the coordinate system selection dialog;
- find required horizontal coordinate system in the list (EPSG codes 6494, 6496 or 6499) and then click Edit button in the same dialog;
- in the opened Edit Coordinate System dialog choose North American Vertical Datum 1988 in the Vertical Datum field;
- input the coordinate system name and click OK.

The system will be displayed in the User-Defined section of the list and you'll be able to save it.

[Jeremiah_ROWE]

Thank you very much for these directions. I never even noticed the EDIT ability there!

[Alexey Pasumansky]

Hello Jeremiah_ROWE,

It was implemented in the version 1.3.0.

Also note that Vertical Datum combo-box would display the available geoid options to the selected projection from the GeoTIFF files that are present in the /geoids/ folder.

[BryanBaker]

Hello,

I followed your procedure and it seemed to work... once.  I gave it a name and hit save but it is not displayed in the list of coord systems.  Additionally, when I repeat the process and hit OK after my edits, it only gives me the option to Cancel. 

I have attached screen shots of the problem.

Finally, when I select the Geoid model 12A, it says the horizontal datum is not compatible and do I want to update to the correct one.  I say yes and it did it, but why is that datum not displayed in my list of available datums in the first place? 

Is there some way to update the list of available datums?

Thank you for your assistance.

Regards,
Bryan

[Alexey Pasumansky]

Hello Bryan,

Only "Cancel"  is active, because no coordinate system is selected in the window.

Where from this dialog is opened? If you have already loaded the coordinates to the Reference pane in this system, then you need to access the coordinate system selection window from the Reference pane setting dialog.

For Geoid 12A we only have undulation grid based on NAD83(2011) (EPSG::6318), so if you require it on a different datum, please provide some reference for it.

[BryanBaker]

Thank you.  This is helpful.  So I believe my issue is workflow related.  All my data is currently WGS84 but I want it in a Projected Coordinate system of State Plane CT Meters based on NAD83(2011) Geoid 12A.

My steps in the reference pane are press "Convert" then I select projected coordinate systems NAD/NSRS(2007) because NAD83(2011) is not in my list of Projected Coordinate Systems.  So then I hit "Edit" and change Vertical Datum to Geoid 12A.  I get warning that it is not supported in 2007 (which is fine) and do I want to "Change to Supported Datum 2011" which I do but I want it Projected as CT State Plane Meters, not Geographic.   I give it a name and save it but it does not convert the WGS to NEZ.  Just the column headings.

So I am wondering if there is some faulty procedure in my workflow.  I am also wondering why Custom projections do not appear in the coordinate system list when I press "Convert" but they do appear in the "Settings"  Because I want to Convert WGS84 to NAD83(2011) G12A.  Not change the setting.  If I press "Convert" and edit the Projection Parameters, it saves the projection but does not perform the conversion.

I hope you can make sense of this.

Regards,
Bryan

 

[Alexey Pasumansky]

Hello Bryan,

The conversion between datums is only possible if TOWGS84 section is available in the coordinate system definition.

[BryanBaker]

TOWGS84?   Ummm.... That totally lost me.  I have not seen that anywhere in any of the coordinate system definitions parameters.  Does this require manual editing of some file?  Which and where?

I really appreciate you assistance and patience.  I am very, very familiar with projections and datums. Just trying to understand how Agisoft deals with it.

Thanks,
Bryan

[BryanBaker]

Maybe it would just be easier to point me to the document or correct way to go from WGS84 to NAD83(2011) Geoid 12A CT State Plane Meters than for me to keep guessing wrong.    There seems to be some difference or confusion on my part between Settings and Convert.

Thanks,
Bryan