DEM Herconditionering >> Lege AgreeDEM

RyanLondeen

<\/HEAD>

Ik heb problemen met de terreinverwerking met ArcHydro.<\/P>

<\/P>

ArcGIS Versie: 10.2.2<\/P>

ArcHydro Versie: 10.2<\/P>

<\/P>

Probleem: Telkens wanneer ik de DEM Herconditionering tool uitvoer, krijg ik een lege Agree DEM als output.<\/P>

<\/P>

Mijn stappen:<\/P>

1. Maak een project aan in een map op mijn Bureaublad (geen spaties en relatief korte bestandslocatie)<\/P>

2. Importeer master DEM raster voor County<\/P>

3. Importeer stroomnetwerk voor county (FEMA)<\/P>

4. Maak een polygoon om de maskerrand voor de projectlocatie in te stellen.<\/P>

5. Extraheer met mask de DEM tot aan de grens<\/P>

6. Knip wtr tot aan de grens.<\/P>

7. Maak een file geodatabase aan<\/P>

8. Stel extents in op de grenslaag<\/P>

9. Stel doel locaties in op de jobmap en geodatabase<\/P>

10. Voer DEM Herconditionering uit<\/P>

<\/P>

Doe ik iets verkeerd in het proces?<\/P><\/BODY><\/HTML>

GaneshchandraMallya

Hi Mark:

I was able to successfully obtain the AgreeDEM when I tried it again today.

Here is what I did (mostly following your tips in this thread as well as your popular ArcHydro thread):

1. Use Windows 7 utility Disk Cleanup to empty the Temp folder.
2. Open a new ArcMap document and add the DEM raster and the stream network shapefile.
3. Ensure that both these files (from step 2) have the same projection. In my case it was UTM 15N.
4. Create a folder for the project e.g. C:\MyProject
5. Save the ArcMap document as C:\MyProject\MyProject.mxd. This step generally sets the target locations correctly.
6. Double-check the target locations before running any ArcHydro functions using ArcHydro toolbar -> ApUtilities -> Set Target Locations -> HydroConfig. When you double click the HydroConfig
   • Raster Data should be pointing to C:\MyProject\
   • Vector Data should be pointing to C:\MyProject\MyProject.gdb
   • Map Name = Layers (Layers is the default name of the dataframe in the ArcMap document)
7. Check the processing extent using Geoprocessing -> Environments -> Processing Extent
   • I set the extent as Union of Inputs
8. Clear Temp folder again using ArcHydro toolbar -> ApUtilities -> Addition Utilities -> Clean User's Temp Folder
9. Run DEM Reconditioning to obtain AgreeDEM.

For the sake of any future GIS enthusiasts who encounter a similar error, I thought I will complete the discussion:

In my opinion, the original issue was not likely due to incorrect processing extents because the AgreeDEM (see attached figure from my initial post) did burn the stream network for the entire study area (burnt streams represented as black pixels spread over the study area- figure is at maximum zoom-out level). However, the entire left half (you can observe a vertical demarcation in the AgreeDEM - showing white region with black pixels on the LHS and a shaded region on the RHS of the AgreeDEM) of the study area (except the pixels burnt as stream) had pixels with value=No_Data. You rightly recommended me to check this again as the legend in the figure was showing white areas to be of high elevations (272-592). Though not shown in the legend, I have confirmed that most of the left half of the AgreeDEM had No_Data.

The values in the AgreeDEM appear to be strange at first look because by default the Symbology (or legend) for AgreeDEM was set to be Classified with inverted color coding compared to the input DEM. Further the AgreeDEM was run with the following parameters: Smooth drop in Z units = 100, and Sharp drop in Z units = 1000 to exaggerate the burning of pixels representing the stream. Same parameters were eventually used in the solution.

I am not able to pinpoint the exact cause for this error, except to agree that one needs to be careful while setting up the project and follow the best practices recommended by experts like you. Finally, if everything fails remember not to give up. Seek help. Start fresh.

I want to thank you again for your insights and detailed explanations for probable causes for this error. It was very helpful.

Best.

Ganesh