Latest Contributions by MattMead

Adam, XS OID 0 is the cross section with OID(Object ID) of 0.  If you open the XScutlines attribute table it should be easy to identify by finding the 0 value in the OID column.  As for -2147220990, that I dont know what it is.  Could you post a screenshot of your setup?  Some things you could check out in the meantime: Do you have any special characters in your Stream Name(ex. !, #, comas, periods, etc)?  Is there just 1 stream centerline and does it touch the cross section only once?  Does only 1 left, right and channel flowpath touch the cross section? ... View more

We did some tests using Spatial Analyst Tools-> Slope to semi-automatically identify levees and other man made earthworks with DEMs that could potentially be used for the same thing.  We found in our tests that the slopes between 1:1 and 2:1 would often also identify the stream banks.  With the symbology of the slope process output raster set to the corresponding slope in degrees(I want to say 30-45 worked best) you can just draw along the outer limits.  If you prefer TINS, 3dAnalyst tools->triangulated surface->Surface Slope I believe does the same thing as the spatial.  That said, unless you are dealing with hundreds of cross sections in your models you would likely be better served time wise just selecting your stream centerline and using Editor->copy parallel to create your approximate stream bank locations and then just use the graphical editor in RAS to manually adjust as needed.  Its pretty rare that we bother trying to draw a bank line to match the stream banks for the same reason you specified...you end up having to fix it anyway. ... View more

Bruce, Are you looking for 3d lines or points along the lines with elevations in an attribute field? If you want 3d lines, use Feature to 3d(I think this was added in 10 or 10.1 so hopefully your version of arc supports it): 1. Customize Menu->Toolbars->Customize...->Commands Tab->search for Feature to 3d(requires 3d analyst) 2. Input Features=NHD layer, Set the height source to your elevation data(DEM or TIN), Save it where ever you want This will create a polylineZ file with elevations stored within the line to make it a 3d shape. If you want points with elevations(requires DEM elevation data and spatial analyst): 1. Convert your lines to points with your preferred process.  I like EZprofiler because i can set the distance between points easily(free here: http://arcscripts.esri.com/details.asp?dbid=16031) 2. Spatial Analyst Tools->Extraction->Extract Values to Points This will attribute your point file with the elevations at each location. ... View more

Good news and bad(maybe) news. The good news is that what you have outlined there is really pretty easy to set up.  you will need: Your structure point file FEMA's BFE lines DEM/raster of the terrain data Spatial Analyst license Step 1. FEMA BFE lines need to be interpolated into a raster. Step 2. Use this tool: Spatial Analyst Tools ->Extraction ->Extract Multi Values to Points: Point file is your structures file, load in both your terrain DEM and the raster of your water surface elevations. This creates fields in your existing structures point file with the name of each raster and attributes it with the raster value at each point's location. Step 3. Create a field in your structures file that you can then use field calculator to calculate the difference in. So that is all you need to do to create the file you are looking for.  The bad news though is that based on what you say it is to be used for, its possibly not going to accurately give you the information you want.  The reason I say this is that FEMA is either going to care about first floor elevations or the lowest adjacent grade which is probably not where the point was placed.  If you have access to a structures footprint file there is a way that you can punch out holes in the terrain raster and then calculate the minimum value for each...Spatial Analyst->Zonal->Zonal Statistics(input feature is the structure file, raster is your terrain, stats type is minimum).  Doing that and using its output instead of the terrain data in Step 2 should give you something a bit closer to what you are looking to do, but again it requires the structure outline which can be a royal pain to develop if its not available.  Sometimes assessors or other county entities(planning dept maybe?) have first floor elevations.  If you can get them in a table you could do a join based on address or parcel ID or something. ... View more

I'm having the same problem. I don't mind which way to use, I just want to delineate the floodplains. But I didn't understand everything you said. Is it that I need to export the results from hecras and once I have it in ArcMap, export the shape containing the cross sections? And then? Could you please explain me a little bit more!!! Thanks in advance You more or less have it right.  I would create the copy of the cross sections before copying in the Hec-ras output, but either way would work.  The only reason I would copy the cross sections first is that I have bad luck with geodatabases getting corrupted when I add fields to the files.  Basically the process I laid out has you manually do what the import process built into georas would do automatically.  Your end result is the cross sections with the appropriate water surface elevations in it.  How you get their is up to you. Once you have your cross sections and elevations all you need to do is use the tools I identified in the previous post and you should be set. ... View more

Georas does weird things when you try working with grids. The georas mapper is such a black box we dont even try to use it anymore.  Based on the line in the error saying its possibly an empty feature class as an output I would first verify that all of your files are in the same spatial reference.  Do you have a 3dAnalyst license?  If so, I would convert your terrain and water surface grids to TINs.  Then you can use 3dAnalyst-> Triangulated Surface->Surface Difference. This outputs a polygon shapefile of your floodplain and has the option to output a depth grid as well.  Hope that helps. ... View more

Wow, yeah definitely not the 2 streams only issue 🙂 As a quick test in another copy of your RAS model create a river reach by just drawing it in and then use move object to try and create a junction on one of your GeoRAS imported streams.  If that fails you at least narrow it down to a RAS issue and not GeoRAS.  If that works though, the only thing I could think to try next would be to export your data into another georas setup a couple stream reaches at a time.  Once everything is broken out into separate import files you can import them into RAS and see if everything junctions correctly and build it up from there. Good luck! ... View more

You wouldn't happen to be working with only 2 stream reaches would you?  If that is the case RAS requires three streams to make a junction.  Some of what you wrote(Snap to end, move object didnt work) makes it sound like you have two streams that come together end to end and you want to make one long reach with distinct names/river stations.  If that is indeed what you want to do you need to make a dummy reach and use that to make the junction.  If you are trying to combine three streams, try making three separate lines in the River file if you havent done that already.  Failing that though, I am at a loss.  Move object should always split the reach as long as there are cross sections on either side of the junction. ... View more

Its saying your River file has a line that crosses a cross section more than once.  In looking at your screenshot though I dont see where that is.  Is it possible that you accidentally copied a cross section into your River file or the other way around?  It gives you the ID numbers that are causing the issue so if that is not the case I would recommend just creating a new mxd and georas files then just copy your original data in. ... View more

Raster calc/map algebra uses the "con(" function to handle such statements. I havent tried using it in the model builder yet, but your statement: "Raster rainfall �?� 200 and Raster rainfall �?� 800 (Raster rainfall + soil humity, 0)" should be: Con(Rainfall >= 200 & Rainfall <= 800,Rainfall + Soil, 0) make sure to have a space between the +,-,= etc and your rasters and numbers or else it wont work. ... View more

I'll let someone else get technical on Z tolerance as it was always explained to me that the Z tolerance was the max difference allowed during the processing.  As for the potential cause for a greater that 1m difference, it is likely due to your resultant raster not having the same extents as your original.  When you convert your raster to a TIN I believe it takes the centerpoint of each cell and uses that location as the "known" elevation for use in triangulating the nodes.  When you take the TIN and convert it back to a raster it may not line those centerpoints back up exactly causing your elevation data to appear to shift.  Technically your data will still be within your Z tolerance of 1, its just that the new raster is using an elevation that is based on a location interpolated between your previous data points.  Check out "snap raster" in the help files.  This forces your DEM/raster files to use a specific grid starting point. ... View more

ET Geowizards does it with Point to Polyline(Z) in the convert menu.  You need to specify a field for it to take the order the points go in as well as the elevations. If you prefer going directly from the text file you can do so by going to the import tab in ET geowizards and selecting "from text file" ... View more

You can skip the georas floodplain delineation by just using your water surface TIN and a terrain TIN with this tool(link below).  Intersect TIN creates a polygon of your floodplain area and a TIN of the depths.  I prefer using this over TIN difference/TIN compare because it creates both files at once instead of having to set up two separate processes.  It is for older versions of Arc, but still works just fine in 10.1 but it does require 3danalyst extension. http://resources.esri.com/help/9.3/arcgisdesktop/com/samples/3D_Analyst/Surface_Analysis/Intersect_Tins/88fdf0db-7dc2-44db-8614-8a6b033e12a4.htm ... View more

This uses the Spatial Analyst extension. In the Spatial Analyst toolbar->options->set the working directory(or something like that, I'm not at my machine at the moment) to where you want the new DEM to be saved. In Spatial Analyst->Raster Calculator type "newDEMname=merge(DEMsurvey,DEMfromAerial,USGSDEM)" without the quotes.  That will combine your DEM's into a single DEM of whatever you call "newDEMname" in the working directory you set. The DEM will be built using the order going right to left(ie USGS will be base, then written over by Aerial, then written over by survey) newDEM=Mosaic(same DEM order) will also work, but when i have overlapping data I prefer merge. NOTE: If your cells are offset or of different sizes, the results might be a little funky Also, if the USGS DEM has way more data than you need, you can clip it down using a polygon shapefile and Spatial Analyst->Extract by Mask if you want to make it a bit more manageable. ... View more