<div style="display: flex; flex-wrap: wrap; white-space: pre-wrap; align-items: center; "><img height="20" width="20" style="border-radius:50%; margin-right: 4px;" decoding="async" src="https://avatars.githubusercontent.com/u/1231218?s=20&v=4" /><strong>1ec5</strong> created an issue <a href="https://github.com/openstreetmap/openstreetmap-website/issues/6618">(openstreetmap/openstreetmap-website#6618)</a></div>
<p dir="auto"><a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="3595133926" data-permission-text="Title is private" data-url="https://github.com/openstreetmap/openstreetmap-website/issues/6504" data-hovercard-type="pull_request" data-hovercard-url="/openstreetmap/openstreetmap-website/pull/6504/hovercard" href="https://github.com/openstreetmap/openstreetmap-website/pull/6504">#6504</a> migrated the map control on the Dashboard page from Leaflet to MapLibre GL JS. GL JS responds to zoom gestures incrementally, so it’s easy to end up at a fractional zoom level. At fractional zoom levels, it underzooms or overzooms raster tiles to fit. The OSM Carto maintainer points out in <a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="3595133926" data-permission-text="Title is private" data-url="https://github.com/openstreetmap/openstreetmap-website/issues/6504" data-hovercard-type="pull_request" data-hovercard-url="/openstreetmap/openstreetmap-website/pull/6504/hovercard?comment_id=3656355664&comment_type=issue_comment" href="https://github.com/openstreetmap/openstreetmap-website/pull/6504#issuecomment-3656355664">#6504 (comment)</a> that OSM Carto wasn’t designed to be underzoomed. Further work on <a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="3257109913" data-permission-text="Title is private" data-url="https://github.com/openstreetmap/openstreetmap-website/issues/6234" data-hovercard-type="issue" data-hovercard-url="/openstreetmap/openstreetmap-website/issues/6234/hovercard" href="https://github.com/openstreetmap/openstreetmap-website/issues/6234">#6234</a> would expose fractional zooming to more prominent maps that show other featured raster tile layers. Back when this site migrated to Leaflet, Leaflet didn’t support a fractional zooming option yet (<a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="133422965" data-permission-text="Title is private" data-url="https://github.com/openstreetmap/openstreetmap-website/issues/1153" data-hovercard-type="issue" data-hovercard-url="/openstreetmap/openstreetmap-website/issues/1153/hovercard" href="https://github.com/openstreetmap/openstreetmap-website/issues/1153">#1153</a>), so we never really considered this implication as far as I can tell.</p>
<p dir="auto">The <a href="https://maplibre.org/maplibre-gl-js/docs/API/classes/RasterTileSource/#roundzoom" rel="nofollow"><code class="notranslate">roundZoom</code></a> option avoids underzooming but exacerbates overzooming: <a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="58822219" data-permission-text="Title is private" data-url="https://github.com/mapbox/mapbox-gl-js/issues/1030" data-hovercard-type="issue" data-hovercard-url="/mapbox/mapbox-gl-js/issues/1030/hovercard?comment_id=76043779&comment_type=issue_comment" href="https://github.com/mapbox/mapbox-gl-js/issues/1030#issuecomment-76043779">mapbox/mapbox-gl-js#1030 (comment)</a>. It may also be possible to disable incremental zooming with the workaround in <a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="1356094480" data-permission-text="Title is private" data-url="https://github.com/maplibre/maplibre-gl-js/issues/1591" data-hovercard-type="issue" data-hovercard-url="/maplibre/maplibre-gl-js/issues/1591/hovercard?comment_id=2748319483&comment_type=issue_comment" href="https://github.com/maplibre/maplibre-gl-js/issues/1591#issuecomment-2748319483">maplibre/maplibre-gl-js#1591 (comment)</a>, but I haven’t tried it to see if the user experience is similar to Leaflet with this feature disabled.</p>
<p dir="auto">Off the top of my head, <a href="https://github.com/mapbox/geojson.io/">geojson.io</a> and the <a href="https://github.com/valhalla/web-app/">Valhalla FOSSGIS demo app</a> also use the default tile zoom strategy. I’m unaware of any other sites that use MapLibre to show raster basemap tiles with a different tile zoom strategy. On the desktop, QGIS consistently overzooms raster basemap tiles, including OSM Carto, but it also underscales the map on HiDPI displays: <a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="3429282252" data-permission-text="Title is private" data-url="https://github.com/qgis/QGIS/issues/63249" data-hovercard-type="issue" data-hovercard-url="/qgis/QGIS/issues/63249/hovercard" href="https://github.com/qgis/QGIS/issues/63249">qgis/QGIS#63249</a>.</p>

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