No Zoom Level 19 Available in Anchorage Alaska imagery basemaps

[KroniK907]

This is probably not the right place for this, but maybe you can tell me who to file a bug report with.

Anchorage Alaska currently does not have any imagery basemap data at zoom level 19. However it does have higher resolution data at zoom level 20. This leaves us in a weird place where zoom level 18 looks fine, zoom level 19 says no data is available, and zoom level 20 has high resolution data.

Currently I am manually fixing this by creating two basemap layers one with the "Imagery" data and one with the "ImageryClarity" data, setting the max zoom on the "Imagery" layer to 18, then setting the minZoom on the Clarity layer to 19, and then putting them in a layer group.

This works, but shouldn't be necessary.

Here is a codepen showing the missing zoom level: https://codepen.io/KroniK907/pen/oNzKyOL

Just zoom in once to see the missing layer. Zoom in again to see the high resolution imagery showing up at level 20.

[jgravois]

not reproducible here: https://www.arcgis.com/home/webmap/viewer.html?webmap=ebdfa4146680410bb952c7d532ea5407#!

might have something to do with #1011 if so, i'm sorry 🤷

[gavinr]

I'm not quite sure yet what's going on here, but would using esri-leaflet-vector be a workaround?

L.esri.Vector.vectorBasemapLayer("ArcGIS:Imagery", {
  apiKey: "< YOUR API KEY HERE >"
}).addTo(map);

https://jsbin.com/tuqutud/2/edit?html,output

[KroniK907]

not reproducible here: https://www.arcgis.com/home/webmap/viewer.html?webmap=ebdfa4146680410bb952c7d532ea5407#!

might have something to do with #1011 if so, i'm sorry 🤷

Well, that seems to indicate that the data is there assuming that they aren't doing some kind of backend trickery to just scale the zoom level 18 image tiles.

So maybe this is the right place to report this issue? Is it possible that something isn't working right in the base L.tileLayer class? I'm not sure how I'd even go about debugging this issue.

[jwasilgeo]

Looking at the network requests in your original codepen, @KroniK907, I am seeing network requests to attempt to fetch tiles at zoom level 19, which likely aren't there and show the default "Map data not yet available" tile content.

Similarly looking into the AGOL webmap viewer, I believe you are seeing tiles from zoom level 18 at map zoom level 19 in the Anchorage area.

But back to esri-leaflet, at one point we reverted what was in PR #1011 (sorry @jgravois!) which I think probably would have fixed this behavior and decided to revisit the enhancement via #1222.

@gavinr also makes a good suggestion above (https://github.com/Esri/esri-leaflet/issues/1255#issuecomment-772162354) to try to use the imagery basemap via the esri-leaflet-vector plugin, instead of waiting on #1222.

[jgravois]

i forgot you'd reverted that PR of mine. that's a good thing!

if the ArcGIS Imagery feedback webmap is only fetching tiles at level 18 and 20, i think it would be prudent to report the problem there.