Any help with using the SAR extract water tool?

[DuncanHornby]

Could anyone in ESRI or the wider community help with this seemingly simple problem of running the extract water tool? Like this user I too get a generic 999999 error.

I have a sentinel 1 dataset, its full name is: S1A_IW_GRDH_1SDV_20200209T110313_20200209T110342_031175_03959E_A378_COG.SAFE

My starting point is to drag the manifest.safe in catalog into the map and it displays as an RGB layer.

I then stepped through the processing sequences as listed in this rather good story map. No errors all seems to work OK.

I then want to run the SAR extract water tool and this is where it all falls apart and there is no guidance as to what the input should be. So when I run the tool it simply errors with 999999.  Reading the help file for this tool it states Calibrate the input radar data to gamma nought using the Apply Radiometric Calibration tool.

OK if I restart the workflow as prescribed in the story map and do a gamma nought radiometric calibration then the next step apply radiometric terrain flattening refuses to run demanding input must be beta nought calibrated!

OK so I think maybe water extraction is something you do before terrain correction? So off I go and look for help. One very quickly arrives at this esri youtube about running the extract water tool, excellent yes?...No! So the presenter shows the tool working. The only comment posted which esri have not bothered to respond to (why?) is a very obvious question of what's the actual input into this amazing tool?

Now from that storymap I have learned that the naming convention helps you understand the processing steps that have been applied to the raster. So looking carefully at the video one can see the raster has been beta nought calibrated, something called deburst, terrain corrected then despeckled. My first question is in their example why wasn't the thermal noise not removed as that is the first processing step prescribed in the story map?

Back to help file, no obvious pointers, even asked esri's ai assistant, that was useless. So I stand stranded between having done the preparation steps and the tool.

Does anyone please have any insight into what exactly is the processing sequence needed so that the input raster is valid for the extract water tool. If its something different requiring a different workflow to ensure the data is suitable for the tool why is this not documented in the help? For the record I'm using arcpro 3.6.2.

[DuncanHornby · Accepted solution]

Good news got the tool working with help from @Aote_Xin !

So lessons learned. 99999 errors are not very helpful particularly when I (yes it was me who was at fault) made a blunder in my choice of DEM. I'm hoping that esri will improve the error reporting of the tool and the usage advice in the help file so other future users don't make the same mistake as me.

So only when @Aote_Xin provided a DEM that worked were we able to see that basically I had downloaded an inappropriate dataset for the tool. I had downloaded a NASADEM from here. This is not an elevation dataset! After digging around in their user guide table 1 on page 3 I determined the NASADEM_SIM was  incorrect and I should have been using their NASADEM_HGT. The NASADEM_SIM is an 8bit 0-255 value raster the sort you might use for a grey scale display. The NASADEM_HGT is an integer raster and appropriate for the Extract water tool.

Also it seems to be best practise but not enforced that the DEM extent should enclose the extent of the SAR dataset.

With a correct DEM and following the sequence:

1. Apply Radiometric Calibration (Gamma Nought)
2. Apply Radiometric Terrain Flattening

Extract Water runs successfully.

So where does one source correct DEMS?  You could, as I  had, go to the primary portal such as EARTHDATA but an alternative worthy of mention is https://opentopography.org/

It's worth mentioning that the YouTube video above gives one the impression that the tool runs super fast, that is definitely not the case for me on an i7, 32GB machine it took about 6 minutes and tinkering around with the minimum area parameter can significantly increase processing time.

When you finally get it to run its pretty awesome! 😁