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I am trying to put together Topographic .Tif rasters (from GMTED data) on an ortographic globe on Qgis 3.4.1, for exemple these 8 layers:

enter image description here

However when I change the projection and one of the various layer appears toward the extremities of the globe, it suddenly dissapears: (the above screenshot used a projection centered on 35°W, the one below on 60°W)

enter image description here

However If I zoom/increase the scale on the rasters that dissapeared, they eventually reappear

enter image description here

It doesn't matter whether I change the scale or zoom, as long as I unzoom at a certain level it disappears.

I encounter the same problem when I make a print layout and add a part of the map on it, if it is unzoomed then the raster disappear.

I tried to check in "scale dependent visibility" in the render part of the layer settings, but it didn't do anything. I also don't think it is a problem with parts of the raster being "behind" the globe and thus not being rendered, since I encounter this problem even when all corners of the raster are on the visible half of the globe, although this glitch happens nearly always on rasters that are near peripherical to the globe.

Thanks for your help.

TheKutKu
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  • Maybe related: https://gis.stackexchange.com/questions/78346/ortho-projection-produces-artifacts and https://gis.stackexchange.com/questions/252006/how-can-i-crop-a-raster-layer-to-a-hemisphere – AndreJ May 07 '20 at 05:55
  • Thanks for your answer

    The first link Is about vector data. And as I described above this happens even when the 4 corners of the raster are well within the visible half, That problem still happens if a raster is "toward the periphery" of the visible half. I tried the method explained in the second, and while I managed to generate an Orthographic TIF of the same GMTED data raster files I encountered the same problem as I described in my original post: It only appeared if the raster wasn't toward the edges.

     – TheKutKu May 07 '20 at 08:59

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It might be an issue with the size of the raster layer. Try generating raster overviews to compress the size of the raster and reduce its resolution to speed up the rendering process. You can do this on QGIS by going to Vector > Miscellaneous > Build Overviews (Pyramids). This makes the layer show only the necessary data on the particular zoomed out scale.

Vince
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Yan
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