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I'm not a regular GIS user.

I'm trying to extract (save for offline use) topographic maps from a couple different sources, but when I load the extracted file, it's either gray with a pattern of white pixels, or nothing renders at all.

I add the data source, add the source as a layer to the project, then Export --> Save As a GeoTIFF. Create VRT is unticked. The extent is the map canvas. If there's supposed to be a specific resolution specified, then I don't know what that is, but I've been using anywhere between 0.5 and 2. The extents download without issue as far as I can tell, and the sources all render perfectly fine when I stream them directly from the source server. I don't know what I'm doing wrong. Here are a few of the REST/XYZ/WMTS sources I've been using:

  1. https://services.arcgisonline.com/arcgis/rest/services/USA_Topo_Maps/MapServer/WMTS/1.0.0/WMTSCapabilities.xml
  2. http://services.arcgisonline.com/arcgis/rest/services/USA_Topo_Maps/MapServer/tile/{z}/{y}/{x}
  3. http://services.arcgisonline.com/ArcGIS/rest/services/World_Topo_Map/MapServer/tile/%7Bz%7D/%7By%7D/%7Bx%7D
  4. https://basemap.nationalmap.gov/arcgis/rest/services/USGSTopo/MapServer [added as REST]
  5. https://basemap.nationalmap.gov/arcgis/rest/services/USGSTopo/MapServer/WMTS/1.0.0/WMTSCapabilities.xml

I've tried exporting raw data and a rendered image. I've tried toying with the resolution. I've tried setting up pyramids, internal and external. My project CRS is EPSG:3857 / Pseudo-Mercator.

What am I doing wrong?

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Using QGIS 3.20 and the GeoTiff export settings Note: CRS is matched from the metadata

enter image description here

Note: you will only get the resolution of the source (these are only images at a maximum of 96dpi) To get higher resolution you need to use Vector Tiles.

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  • Something about this seems to have worked. I'm not sure why, but either way, thanks very much. I'm guessing this has something to do with QGIS not wanting to render extremely large tiffs, even when pyramids are used. The machine I'm using is no slouch by any stretch. The only thing I did differently was turn the resolution way down. 10 for horizontal and vertical seems to capture enough detail for my purposes.
    – No1Nos
    Aug 1 at 18:54
  • Quick side note though.. When I used the same number for rows and columns, the image came out garbled. Changing the rows and columns to match the aspect ratio of the map extent fixed this.
    – No1Nos
    Aug 2 at 0:14

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