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Has anyone been able to add the FEMA NFHL to an ArcGIS Online map?

KennyMack

If I add it to a map that already has a basemap, I get the error message

The item, Web Map Service NFHL, can not be added to the map because its coordinate system can't be adjusted to align properly with the basemap.

If I add it to an empty map and click the 'Use as Basemap' checkbox, it is added in the legend but no features are visible in the map. Even at a location where I know it should be.

Is this WMS, or any WMS that can't align to web mercator, unusable in the arcGIS online map viewer?

Thanks,
Kenny

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Mike Minami

The reason you are seeing the error message is because the WMS doesn't support Web Mercator. You can "GetCapabilities" of the WMS to see what coordinate systems it does support. Web maps use the basemap to define the coordinate system of the map. Thus, by setting the WMS as the basemap, the web map will assume the coordinate system of the WMS. Any layers you subsequently add to the map must support the coordinate system of the WMS.

I'm not sure why the features aren't being drawn. Can you share the URL to the WMS?

Thanks,

Mike

KennyMack

Sure, it's

https://hazards.fema.gov/wmsconnector/wmsconnector/Servlet/NFHL?REQUEST=GetCapabilities&SERVICE=WMS

So even if this WMS works as a basemap--which as I said it is not, for me currently, I cannot see the features--I would ideally like to use it as an overlay on an aerial or other basemap. Will this not be possible, if I have to use this flood layer as the basemap?

I suppose I could add an aerial layer (non-basemap), then add the NFHL service again as a layer? Maybe that would work, if you can have a WMS twice in a map.

Mike Minami

I've found this WMS that seems to be related...

http://www.fema.gov/library/viewRecord.do?id=3292

The URL you add to a web map is this:

http://hazards.fema.gov/wmsconnector/wmsconnector/com.esri.wms.Esrimap/NFHL?

If you add this to a web map, it will display over the imagery basemap, which supports GCS_WGS_1984.

The reason why you're probably not seeing any data when you make the WMS the basemap is because none of the layers are 'turned on' by default in the WMS. And when you make it a basemap, there's no way to do it through the user interface. I'm not sure if you can specify to turn on layers on the URL to the WMS...

Mike

Mike Minami

ok, it seems we have the same service. You should be able to add this to a new map that has no additional layers in it. The basemap you'll see is an imagery basemap that supports GCS_WGS_1984. Here's a description of that service.

http://www.arcgis.com/home/item.html?id=10189d5ffbce4ef48f5bcc0661cfaff9

You'll need to turn on some layers in your WMS in the Contents panel of the map. Click the name of the WMS layer, and it will expand to show the sub-layers.

Thanks,

Mike

KennyMack

Hmm it still doesn't work for me. I

1. start a new map
2. without changing the basemap or doing anything else, I Add the NFHL WMS you provided above (or the first one). Not as a basemap.
3. the basemap (Topographic) automatically changes to ESRI Imagery World 2D, and the NFHL is added. But no features are visible.
4. As you said, by default none of the individual layers are on, so I turn on some on. But nothing ever shows.

Does something different happen when you add it? If I try to change the basemap to Imagery or others, I get that error message about the coordinate system.

Thanks

Mike Minami

I can draw flood data availability and Preliminary Maps Issued. Some of the other layers don't seem to draw.

Ahhh, there seem to be scale dependent layers. As you zoom in, more show up.

Mike

KennyMack

Mike-- it's working for me now. Interestingly I am on a different computer than I was earlier, I am at home rather than at the office. I wonder if there is a firewall issue. But in any case, thanks for your time! I do wish the FEMA WMS would work with one of the other imagery basemaps, this older one isn't very good for NYC, the buildings are all askew rather than top-down proper orthophoto. But that's not an Esri issue, is it?

Thanks again,
Kenny

KennyMack

I can add the standard imagery and street labels (world transportation) layers on top of the basemap imagery layer, and under the flood data, so that's better. I can't find the Bing aerial or hybrid layers though, are they only available as "basemap" layers and can't be added otherwise?

-Kenny

Mike Minami

Bing streets and imagery services are not services Esri hosts, so I don't know how to access them directly.

Mike

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