How to force WMS to return actual image (not blank image) at all zoom levels?

Question

Some WMS (especially the ones made through ArcGIS) only returns actual images with data at certain zoom levels. At other zoom levels, it will return blank images. I know the server is setup to do that but is there a way around this to force WMS to return images with data at all zoom levels?

The server returns actual image data at this zoom level:

https://hazards.fema.gov/nfhl/services/public/NFHLWMS/MapServer/WmsServer?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&BBOX=-98.12492909258571672,28.30800648431628375,-98.07080887354277365,28.3716343094073089&CRS=CRS:84&WIDTH=666&HEIGHT=783&LAYERS=4&STYLES=&FORMAT=image/png&DPI=120&MAP_RESOLUTION=120&FORMAT_OPTIONS=dpi:120&TRANSPARENT=TRUE

The same server returns a blank image at higher zoom level:

https://hazards.fema.gov/nfhl/services/public/NFHLWMS/MapServer/WmsServer?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&BBOX=-98.15361443391026341,28.28411557681083721,-98.04537399582437729,28.41137122699289463&CRS=CRS:84&WIDTH=666&HEIGHT=784&LAYERS=4&STYLES=&FORMAT=image/png&DPI=120&MAP_RESOLUTION=120&FORMAT_OPTIONS=dpi:120&TRANSPARENT=TRUE

(note that it is made using ArcGIS MapServer)

Another server that returns at all zoom level (GeoServer):

https://www.mrlc.gov/geoserver/ows?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&BBOX=27.76940466477179115,-98.55520921245411614,28.78744986622823632,-97.68928570776702713&CRS=EPSG:4326&WIDTH=666&HEIGHT=784&LAYERS=mrlc_download%3ANLCD_2016_Land_Cover_L48&STYLES=&FORMAT=image/png&DPI=120&MAP_RESOLUTION=120&FORMAT_OPTIONS=dpi:120&TRANSPARENT=TRUE

Answer 1

If you look at the GetCapabilities answer of that server https://hazards.fema.gov/nfhl/services/public/NFHLWMS/MapServer/WmsServer?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetCapabilities you can see that layer 4 has a scale limit that is set with keyword MaxScaleDenominator. The administrator of the service has considered that it is not appropriate to show the layer when the scale is smaller than 1:47247.023810 (small scale = big denominator). User can not override this server side configuration.

This is how the WMS 1.3.0 standard defines scale denominators

7.2.4.6.9 Scale denominators

The and elements define the range of scales for which it is appropriate to generate a map of a Layer.

<Layer queryable="1">
<Name>4</Name>
<Title>
<![CDATA[ Flood Hazard Zones ]]>
</Title>
<Abstract>
<![CDATA[ Labels for flood zones. ]]>
</Abstract>
<CRS>CRS:84</CRS>
<CRS>EPSG:4326</CRS>
<CRS>EPSG:4269</CRS>
<EX_GeographicBoundingBox>
<westBoundLongitude>-170.848402</westBoundLongitude>
<eastBoundLongitude>145.832194</eastBoundLongitude>
<southBoundLatitude>-14.375160</southBoundLatitude>
<northBoundLatitude>66.610582</northBoundLatitude>
</EX_GeographicBoundingBox>
<BoundingBox CRS="CRS:84" minx="-170.848402" miny="-14.375160" maxx="145.832194" maxy="66.610582"/>
<BoundingBox CRS="EPSG:4326" minx="-14.375160" miny="-170.848402" maxx="66.610582" maxy="145.832194"/>
<BoundingBox CRS="EPSG:4269" minx="-14.375160" miny="-170.848402" maxx="66.610582" maxy="145.832194"/>
<Style>
<Name>default</Name>
<Title>
<![CDATA[ Flood Hazard Zones ]]>
</Title>
<LegendURL width="300" height="144">
<Format>image/png</Format>
<OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://hazards.fema.gov/nfhl/services/public/NFHLWMS/MapServer/WmsServer?request=GetLegendGraphic%26version=1.3.0%26format=image/png%26layer=4" xlink:type="simple"/>
</LegendURL>
</Style>
<MaxScaleDenominator>47247.023810</MaxScaleDenominator>
</Layer>

There is no issue with the server but it works as it is configured to work.