Unable to update cross scetion elevations using HEC-GeoRAS

[JamesKeys]

Hi

I???ve created some Cross Section CutLines in ArcGIS 9.3.1 using HEC-GeoRAS 4.3.93 and converted them to 3D lines by extracting elevations from a TIN model. However, the TIN model doesn???t have elevations for the river channel. Therefore I???ve tried to update the channel part of the cross section profiles by using the ???Update XS CutLine Profiles??? function in HEC-GeoRAS. The function uses bathymetry points to snap to the closest point on the cutline profile.

My problem is that it doesn???t work. Below are examples of the error messages I???m receiving:

Failed to update elevation XS OID 1 at station: 7544.006 Item not found in this collection

Failed to update elevation XS OID 2 at station: 7480.642 Unable to cast COM object of type ???System._ComObject??? to interface type ???ESRI.ArcGIS.Geometry.IPolygon???. This operation failed because the QueryInterface call on the COM component for the interf???.*

*The message stops there, it doesn???t allow me to read the rest of it.

I have no idea what these messages mean and how to fix them. If anyone is able to help me then I would be very grateful

Thanks

James Keys
Postgraduate at University of Brighton, UK

[MattMead]

I could never get the 4.3.93 version to even install correctly(it would install,but never show up in Arc) so I cannot comment on your specific issue, but there appears to be a new version of georas out Geo-RAS 4.3 for Arc 9.3.  I dont know if upgrading will solve your issue or not, but it can't hurt.

Also, does your channel modification have to be done in Arc or can you just use what is built into HEC-RAS?  You have a couple different options for channel modification in HEC-RAS 4.1 that work pretty well. 

Good luck and let us know if anything works for you.

[JamesKeys]

Matt

Thanks for your post. I managed to integrate my channel cross section point data with the floodplain tin by using the Add features to tin function in 3D Analyst. When I added the XSCutlines using GeoRAS and converted them to 3D the representation of the channel looked alot better.

Problem solved!

[GabrielaWerren]

Hello, I have a similar problem.

I have modified my XS cutlines elevation in HEC-RAS and I would like to use this geometry to update my original TIN in order to get some correct flood maps.
But I find no way to export the elevation data back to GIS. Is that possible? Thank you for your answer.

Gabriela

[MattMead]

You can probably just skim most of this, but I've written step by step instructions in the event someone else needs the additional info.  Its also written based on GeoRAS 4.1.1 as each successive version seems geared towards pushing people into HEC's RAS mapper(or it just flat out doesnt work on our machines)

1)In HEC-RAS you can export the GIS data out of RAS by going to(in the main HEC-RAS window) File->Export GIS Data...

2)In the new window check the box for "User defined cross sections" in the lower left. 

3)Back in HEC-GeoRAS, convert the exported ras file to XML by selecting the button with two arrows going in a circle(I'm using an older version of GeoRAS that still works with 9.3 so newer versions may be different). 

4)In the RAS Mapping tab select "Layer Setup"
Type in a name in the box next to new analysis, select your XML file for RAS GIS export file, dont worry about the terrain section, then just select a folder you want the data stored in for Output directory.

5)In the Ras mapping tab, select "Read RAS GIS export file"
This should automatically create the following files: River2d(centerline), Bounding Polygon, XS Cut Lines, and XS Cut Lines 3d.

6) the XS cutlines 3d is a 3d polyline of whatever is in RAS.  When you go to modify your TIN, set the elevation data source to be "feature Z value" and it should work.

I'm not sure if this will work quite how you want it though because it will only have the new data at those cross sections and it will just linearly interpolate between them when you update/create a tin from them.

Hope this helps.  Let us know if it works for you or you find a better way.

[GabrielaWerren]

Thank you, I had finally found the export option.
The TIN interpolation needs an increased number of cross sections for an acceptable result.
It works for me as the initial data was not very accurate itself. Thanks again.
Gabriela