WMS Layers: broken?

I notice that WMS layers are failing to load on some of the demos, for example here: https://ships.lib.virginia.edu/neatline/show/iliad-book-2

Following the example given at https://gist.github.com/waynegraham/c7d9ae298e0fe977f0ea I created a /neatline/layers/wms.json definition file, linking to wms resources on three different servers. None of them could be displayed.

It appears that the wrong zoom level is being requested by my Neatline Exhibit for these layers, consistently several levels below the coincident requests for OpenLayers base map tiles. I suspect that the x & y coordinates being requested are also wrong.

The Digital Atlas of the Roman Empire have recently updated the url for their map tiles, which are used in the Catalogue of Ships Neatline exhibits. We’re in the process of updating those exhibits, the map layers should be working again soon. I believe the new url for the tiles is: http://dh.gu.se/tiles/imperium/{z}/{x}/{y}.png

Thank you for the suggestion, Elizabeth. In fact I’ve been using the new url, without realising that the Iliad book was using an outdated one. I have the urls defined in json as “https://dh.gu.se/tiles/imperium/${z}/${x}/${y}.png”.

If I load my test Exhibit with the Stamen base layer, and zoom in so that it fetches tiles at zoom level 12, and then switch to the Pelagios/imperium base layer without altering the zoom, the system requests (unavailable) tiles at zoom level 5 and entirely different x & y coordinates. Is that a correct behaviour?

Hi stephengadd,
That does seem to be the correct behavior. Are the Pelagios tiles loading ok at other zoom levels? According to their documentation, the tiles are only available for zoom levels between 4 and 11, so anything outside that would bring back an error message. The tiles are also only available over certain parts on the globe, and error messages will appear while viewing outside of those bounds as well. Please let me know if you continue to encounter any issues.

Hello again, Elizabeth, and thanks for your perseverance. It’s not only the Pelagios tiles that are failing to load (for England): the system consistently requests tiles (from all of the wms.json-defined servers) 7 zoom levels below those that it requests for the same viewport from Stamen or OpenStreetMap. I wonder if it is significant that my Exhibit’s initial view is at Zoom-7, with the system calling for Zoom-0 of the wms.json maps?