Re-implementation of tile merging based on mercantile #50
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Excellent! I think this will make |
| assert_array_almost_equal(ext, (0.0, 939258.2035682457, | ||
| 6261721.35712164, 6887893.492833804)) | ||
| assert_array_almost_equal(ext, (0.0, 939258.2035682457, | ||
| 6261721.35712164, 6887893.492833804)) |
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this was duplicated with the line above
| assert_array_almost_equal(ext, (0.0, 939258.2035682457, | ||
| 6261721.35712164, 6887893.492833804)) | ||
| rtr_bounds = [-613.0928221724841, 6262334.050013727, | ||
| 938645.1107460733, 6888506.185725891] |
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This needed to be updated, because the shape of the img array changed (and therefore also the transform calculation when writing the merged tiles with rasterio)
| assert_array_almost_equal(ax_extent, ax.images[0].get_extent()) | ||
| assert ax.images[0].get_array().sum() == 75687792 | ||
| assert ax.images[0].get_array().shape == (256, 511, 3) | ||
| assert ax.images[0].get_array().sum() == 75853866 |
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all those small number changes are due to the fact that the 1 row/column on 256 is no longer incorrectly dropped when merging the tiles -> see also the shape changes; they are now multiples of 256)
darribas
reviewed
Jan 17, 2019
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Nice!!! I'd say, add documentation for |
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This PR removed the use of cartopy's
merge_tileswith a custom implementation(related to https://github.com/darribas/contextily/issues/4 and SciTools/cartopy#792).
It seemed this tile merging can actually rather easily be done, using some of the features of
mercantile(which is already used to calculate the web tile x and y numbers given the zoom and bounds), and using some assumptions about the fact that we only deal with web map tiles (all rectangular equal sized images for a given extent).Just pushing this now to show the implementation. I didn't yet look at or update the tests.
I actually expect the tests to be failing, as while doing this, I discovered that there is a bug in the current implementation (we are overlaying the tiles with one pixel overlap, so losing one pixel row, which gave a subtle hardly noticeable difference (only noted it by comparing the final array of both methods, you need to zoom in a lot to actually see it in the image).