[bug] [core] some (small?) terrain geotiffs don't load at certain zoom levels

Description

For some geotiffs (possibly ones covering a relatively small area), the following [1] condition is satisfied for most zoom levels, that is, tileFound gets set to false. Identical creation options with a larger geotiff (in terms of area on the globe) result in a working geotiff. Notably, commenting this out (leaving tileFound as true) successfully works around the issue.

[1] https://github.com/osmandapp/OsmAnd-core/blob/2720aaebc98ebecfaf1a3f6b57fe97f2a0173133/src/GeoTiffCollection_P.cpp#L1040

Steps to reproduce

Create an OsmAnd-compatible terrain geotiff of a rectangular area about 7000km^2. Pixel Size = (7.735852665470224,-7.735852665470224) was the lowest resolution tested, though it didn't seem that a different resolution had any impact.

Actual result

The 3D terrain is only visible when zoomed out a certain amount. Zooming in a bit shows the same LOD but now blurry, zooming in even more doesn't show the 3D terrain at all. This is consistent with visibility / lack thereof of the grayscale representation of the geotiff (numeric 9 in `bird).

Expected result

The 3D terrain continues to be visible when I zoom in.

Your Environment (required)

I used bird with the latest commit of osmand-core.

osmandapp / OsmAnd