How do I add a vertical coordinate system to my raster so that I can run the new viewshed 2 tool?

[BriannaCarver1]

I want to use the new Viewshed 2 tool but when I put my raster into the tool it gives me warning 010451 which says "Input elevation raster should have a vertical coordinate system that has heights reference to a spheroid." The help page on this is very vague and I cannot figure out how to assign a vertical coordinate system to my raster. I have found pages saying that there is no way to project between vertical coordinate systems in ArcGIS but it seems like there must be some way to assign a vertical coordinate system to a raster so that you can use the Viewshed 2 tool. Is there a way to do this?

[DanPatterson_Retired]

Perhaps Melita Kennedy​ could shed some light on what the 3D people are to do, since there is truly a dirth of information to guide them in the help topic.

[JosephChimento]

I would also appreciate a response.  I have tried to reproject my raster while explicitly stating the vertical coordinate system using a number of different ellipsoids (just to troubleshoot).  Nothing worked. 

Thanks!

[MelitaKennedy]

Brianna, I'm checking on it. As far as I'm aware, the Define Projection tool and a raster's property page do have VCS implemented yet. I just tried a 10.4.1 beta and don't see how to add a VCS to a raster.

Joseph, again, as far as I'm aware, rasters are not explicitly supporting vertical transformations yet. We just added that functionality for vector data to the Project Tool in ArcGIS for Desktop 10.4.0.

Melita

[MelitaKennedy]

If you use the Define Projection tool on a raster, you should have both the XY and Z coordinate system tabs. You must set the XY coordinate system first.

When I did this, I still could not see the vertical coordinate system when I looked at the spatial reference on the data's property page in catalog. If I opened the Geodata transform, then it was listed in its well-known text form.

Melita

[DavidAllen]

I had students facing this same problem. We had a file called BigBend in geographic coordinate system GCS_WGS_1984. Note that the units are in Degrees.

Take the unprojected elevation raster and use the Raster Calculator to create a Raster Attribute Table.

  int(BigBend_dem.tif)

... new output something like BigBend_INT

The reproject the new file into UTM.

Project Raster - give it a new output file name (BigBend_Proj), set the resample technique to Cubic (NOT nearest) THEN

set the output to Projected Coordinate System > UTN > North America > Nad1983 HARN UTM Zone XX (whatever your UTM zone is).

Now try running the slope tool and let me know if that works.

[EzekielBaye1]

Still not working, any update?  I just tried to create a viewshed for a raster that has a vertical datum and still got the 010451 error.

[XuguangWang]

There are two types of vertical coordinate systems. One references a spheroid and the other references a gravity-related surface. See the following help page: Vertical datums—Help | ArcGIS for Desktop 

Viewshed 2 require the height of the vertical coordinate system reference a spheroid. If it references a gravity-related surface, then the warning message 010451 will still show.

However, you should be able to run the tool and get a result even though the message is shown.

[EzekielBaye1]

Thanks, I've tried both (geoid-based and spheroid/ellipsoid based). Neither works, just get the same error message.

[XuguangWang]

Just to clarify it a little, without a vertical coordinate system, the tool will still be able to run, just that it will assume the input raster's Z values and XY coordinate system are in the same unit.

So, if your raster's Z values and XY coordinate system are already in the same unit, you don't need a vertical coordinate system.  You can ignore this message and still get a correct result from Viewshed 2.

If your raster's Z values are in a unit different from XY units (e.g., feet vs meters), and you don't want to use a vertical coordinate system, you must first convert the Z values into XY unit by applying a Z factor before using it in Viewshed 2 tool.