feat(config): Add resizeKernel into the config tileset then disable fastShrinkOnLoad. BM-1146 #3377
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@blacha - We thought about how to carry through a But haven't figured out a clean way to do it. |
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… pixels BM-1146 (#3379) ### Motivation As a Basemaps user, when I view the [NZTopo Raster Maps][nztopo-raster-maps] from afar (low zoom level), I can see black edge artifacts around the perimeter of the imagery. | [Topo 50][basemaps-topo50] | [Topo250][basemaps-topo250] | | - | - | | ![][topo50] | ![][topo250] | | Appears between zoom levels `0-6` inclusive. Hard to notice when zoom level is `>= 6.5` | Appears between zoom levels `0-4` inclusive. Hard to notice when zoom level is `>= 4.5` | _You may need to open each image/link in a new tab to see the black lines more clearly._ #### Problem We suspect the issue resides in the way the **basemaps/tiler** composes a small tile. The resizing down of many pixels into one, causes artifacts to appear where opaque pixels meet transparent pixels. #### Solution There is already a ['workaround' fix][kernel-pr] that treats the symptoms of the black edge artifacts. This work, however, seeks to treat the source of the issue by providing a mechanism to replace all transparent pixels with opaque pixels. The effect being to erase such areas where opaque pixels meet transparent pixels. ### Modifications **basemaps/cogify** - We have added a `background` parameter to the `cover` command. - When the user provides the parameter, the `create` function will perform two additional `gdal` steps after `gdalwarp` and before `gdal_translate`, to ensure that any and all transparent pixels that would otherwise appear in the resulting tile, are replaced with the provided background colour. - `gdal_create` - To create a background image where all pixels are set to the provided background colour. - `gdalbuildvrt` - To layer the background image behind the source GeoTIFF files after reprojection. ### Verification | For a given tile | What cogify usually makes | What cogify can now make | | - | - | - | | ![][verification-tile] | ![][verification-before] | ![][verification-after] | | Example shown: [9-4-325][basemaps-9-4-325] - Web Mercator (EPSG:3857) | No transparent pixels are overwritten. | All transparent pixels are overwritten with the provided background colour. | <!-- links --> [nztopo-raster-maps]: https://dev.basemaps.linz.govt.nz/@-41.8899962,174.0492437,z5?style=topo-raster&i=topographic&config=TmVmbYRQjL9T2JWgyaSie193b4D1qZnBD8hjaSqPFYSsEvEYYhaGYKrcp1HoDE7nHXaP89x5RKia68nGwyRKku4ExE7QvB424FYmjokRMr2qXgj6oehUjHaB27QiY6d [basemaps-topo50]: https://basemaps.linz.govt.nz/@-40.4900187,173.5118508,z5?style=01JE7PGRG2AHNAN80CVCBK5JS1&i=01JE7PGRG2AHNAN80CVCBK5JS1&config=5LN3whfVkKeLNsSo5jGHMuw3a3bk5rR1ekotn4iApaGccpE1D8L2hLZdbsYkzbUrGCFpy2jXFkbngKguAkob2ZKZHKkKGTw6xx1f14Zxe2VaPmUV3PNRTJero5NDH1WgtA16AnKtaRVXQ7KaQevPzeTfwNmxdWZECGqDkps59ifDDuTAQJXXJK6rfMk3tF15s&debug=true [basemaps-topo250]: https://basemaps.linz.govt.nz/@-41.8971463,173.1394504,z4?style=01JE7NBEJHND65K0WWWB9PWXQZ&i=01JE7NBEJHND65K0WWWB9PWXQZ&config=L8TuzSUutDHnXXerPsYTDJdYLrUMAR6yseMyXuNiLyqvD5SPvX6E3CkoPoqhkogKnBCaQpbQ7LUHiSXGsM9ctAVTvjWU8BnSaV3SrRRGDULg5PSGz8thtzn5BGc28bijrqq677m9gSHJqVdwXPsjQ78pKez8TMncCYth2s4npjkmokz7q2r1GgMumQ3WTjT72y&debug=true [topo50]: https://github.com/user-attachments/assets/aaa16253-efed-45b9-a6bd-fb6054b33927 [topo250]: https://github.com/user-attachments/assets/64655fe0-b5ad-4036-aab6-2810fef3c578 [kernel-pr]: #3377 [basemaps-9-4-325]: https://basemaps.linz.govt.nz/@-43.8859446,-176.8266051,z8?debug=true&debug.tile=true [verification-tile]: https://github.com/user-attachments/assets/2159eb1d-3009-4aec-a747-d886cd51df32 [verification-before]: https://github.com/user-attachments/assets/3889e3a2-c784-4436-94d4-f264dc546866 [verification-after]: https://github.com/user-attachments/assets/89018eb0-4aad-437d-a4fd-f4f62c10eb54 --------- Co-authored-by: Wentao Kuang <wkuang@linz.govt.nz> Co-authored-by: Blayne Chard <bchard@linz.govt.nz>
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Motivation
As raster Topo map got edge effects on low zoom levels usually below zoom 6, like following.
We have tests that with output resize kernel of
mitchelland disable the fastShrinkOnLoad for lower scales levels will fix this problem.Modifications
Add the resiseKernel setting in the config bundle, so that we can bundle it into server.
disable
fastShrinkOnLoadfor theresize.scaleless than 0.125.Not fix yet: The virtual tileset for
topo-raster-50kandtopo-raster-250kwon't fix as we can't propagate the resize kernel from combined tileset -> imagery config -> virtual tileset. Unless we add optional resizeKernal property for imagery config.Verification
Local test.
