Freemap Tileserver

Data preparation

Compile GDAL for JXL compression support. Use GDAL 3.10 or later.

Slovakia

Download part of Ortofotomozaia SR you want to process from and extract it. Then build VRT:

gdalbuildvrt -a_srs EPSG:8353 all.vrt *.tif

Next create cutline for alpha mask:

1. create a tile index file gdaltindex tmp.gpkg *.tif && ogr2ogr -f GPKG -t_srs EPSG:8353 index.gpkg tmp.gpkg && rm tmp.gpkg
2. download lms_datum_snimkovania_#.zip where # is 2 or 3
3. dissolve lms_datum_snimkovania:

   ogr2ogr \
     -f GPKG \
     sk-area.gpkg \
     /vsizip/lms_datum_snimkovania_2.zip/lms_datum_snimkovania_2_cyklus.shp \
     -nln dissolved \
     -nlt POLYGON \
     -dialect sqlite \
     -sql "SELECT ST_Simplify(ST_MakePolygon(ST_ExteriorRing(ST_Buffer(ST_Union(geometry), 0.00001, 1))), 0.1) AS geometry FROM lms_datum_snimkovania_2_cyklus" \
     -a_srs EPSG:8353

4. dissolve the tile index

   ogr2ogr \
     -f GPKG \
     zapad-tiles.gpkg \
     index.gpkg \
     -nln tiles \
     -nlt POLYGON\
     -dialect sqlite \
     -sql "SELECT ST_Union(geom) AS geometry FROM 'index'" \
     -a_srs EPSG:8353

5. create a vector mask

   ogr2ogr -f GPKG combined.gpkg sk-area.gpkg -nln dissolved
   ogr2ogr -f GPKG -update -append combined.gpkg zapad-tiles.gpkg -nln tiles
   ogr2ogr -f GPKG intersection.gpkg combined.gpkg \
     -dialect sqlite \
     -sql "
       SELECT ST_Intersection(a.geometry, b.geometry) AS geometry
       FROM tiles a, dissolved b
       WHERE ST_Intersects(a.geometry, b.geometry)
     " \
     -nln intersection \
     -nlt POLYGON \
     -a_srs EPSG:8353

6. rasterize the mask

   gdal_rasterize \
     -burn 0 \
     -at -i \
     -init 255 \
     -tap \
     $(gdalinfo -json all.vrt | jq -r '"-te \(.cornerCoordinates.upperLeft[0]) \(.cornerCoordinates.lowerRight[1]) \(.cornerCoordinates.lowerRight[0]) \(.cornerCoordinates.upperLeft[1]) -tr \(.geoTransform[1]) \(-.geoTransform[5])"') \
     -ot Byte \
     -of GTiff \
     -co TILED=YES \
     -co COMPRESS=DEFLATE \
     -co BIGTIFF=YES \
     stred-tilemask.gpkg stred-alpha-mask.tif

Finally create the warped and masked tif.

ZOOM_LEVEL=20 # for "2 cyklus" use  19

calc_tr() {
    zoom_level=$1
    echo "scale=20; 2 * 4 * a(1) * 6378137 / (256 * 2 ^ $zoom_level)" | bc -l | sed 's/^\./0./'
}

CT='+proj=pipeline +step +inv +proj=krovak +lat_0=49.5 +lon_0=24.8333333333333 +alpha=30.2881397527778 +k=0.9999 +x_0=0 +y_0=0 +ellps=bessel +step +inv +proj=hgridshift +grids=Slovakia_JTSK03_to_JTSK.gsb +step +proj=krovak +lat_0=49.5 +lon_0=24.8333333333333 +alpha=30.2881397527778 +k=0.9999 +x_0=0 +y_0=0 +ellps=bessel +step +inv +proj=krovak +lat_0=49.5 +lon_0=24.8333333333333 +alpha=30.2881397527778 +k=0.9999 +x_0=0 +y_0=0 +ellps=bessel +step +proj=push +v_3 +step +proj=cart +ellps=bessel +step +proj=helmert +x=485.021 +y=169.465 +z=483.839 +rx=-7.786342 +ry=-4.397554 +rz=-4.102655 +s=0 +convention=coordinate_frame +step +inv +proj=cart +ellps=WGS84 +step +proj=pop +v_3 +step +proj=webmerc +lat_0=0 +lon_0=0 +x_0=0 +y_0=0 +ellps=WGS84'

RES=$(calc_tr $ZOOM_LEVEL)

/usr/local/bin/gdalwarp -s_srs 'EPSG:8353' -t_srs 'EPSG:3857' -ct $CT -tr $RES $RES -tap -r lanczos -of GTiff -co TILED=YES -co BIGTIFF=YES -co COMPRESS=JXL -co JXL_DISTANCE=1 -co JXL_LOSSLESS=NO -co NUM_THREADS=ALL_CPUS -wo NUM_THREADS=ALL_CPUS -multi Ortofoto_2021_stred_jtsk_rgb/all.vrt stred-warped-jxl.tif

/usr/local/bin/gdaladdo -r lanczos --config BIGTIFF_OVERVIEW YES --config COMPRESS_OVERVIEW JXL --config JXL_LOSSLESS_OVERVIEW NO --config JXL_DISTANCE_OVERVIEW 1 --config GDAL_NUM_THREADS ALL_CPUS --config NUM_THREADS_OVERVIEW ALL_CPUS -ro stred-warped-jxl.tif

Czech republic

TODO

gdaltindex vychod-tileindex.gpkg -lyr_name index new/*.jpg

ogr2ogr \
  -f GPKG \
  vychod-tileindex-dissolved.gpkg \
  vychod-tileindex.gpkg \
  -nln dissolved \
  -nlt POLYGON \
  -dialect sqlite \
  -sql "SELECT ST_Union(geom) AS geometry FROM 'index'" \
  -a_srs EPSG:5514

ogr2ogr \
  -f GPKG \
  result.gpkg \
  admin.gpkg \
  -nln tiles \
  -nlt POLYGON \
  -dialect sqlite \
  -sql "SELECT ST_Buffer(geom, 99.5, 16) AS geometry FROM administrative_units" \
  -a_srs EPSG:5514

ogr2ogr -f GPKG -update -append result.gpkg vychod-tileindex-dissolved.gpkg -nln dissolved

ogr2ogr -f GPKG intersection.gpkg result.gpkg \
  -dialect sqlite \
  -sql "
    SELECT ST_Intersection(a.geometry, b.geometry) AS geometry
    FROM tiles a, dissolved b
    WHERE ST_Intersects(a.geometry, b.geometry)
  " \
  -nln intersection \
  -nlt POLYGON \
  -a_srs EPSG:5514

gdalbuildvrt vychod.vrt new/*.jpg

gdal_rasterize \
  -burn 0 \
  -at -i \
  -init 255 \
  -tap \
  $(gdalinfo -json vychod.vrt | jq -r '"-te \(.cornerCoordinates.upperLeft[0]) \(.cornerCoordinates.lowerRight[1]) \(.cornerCoordinates.lowerRight[0]) \(.cornerCoordinates.upperLeft[1]) -tr \(.geoTransform[1]) \(-.geoTransform[5])"') \
  -ot Byte \
  -of GTiff \
  -co TILED=YES \
  -co COMPRESS=DEFLATE \
  -co BIGTIFF=YES \
  intersection.gpkg \
  vychod-alpha-mask.tif



gdal_edit -unsetnodata mask...

nice /usr/local/bin/gdalwarp -s_srs 'EPSG:5514' -t_srs 'EPSG:3857' -tr 0.14929107086948486475 0.14929107086948486475 -tap -r lanczos -of GTiff -co TILED=YES -co BIGTIFF=YES -co COMPRESS=JXL -co JXL_DISTANCE=1 -co JXL_LOSSLESS=NO -co NUM_THREADS=ALL_CPUS -wo NUM_THREADS=ALL_CPUS -multi tif/all.vrt zapad-warped-jxl.tif && nice /usr/local/bin/gdaladdo -r lanczos --config BIGTIFF_OVERVIEW YES --config COMPRESS_OVERVIEW JXL --config JXL_LOSSLESS_OVERVIEW NO --config JXL_DISTANCE_OVERVIEW 1 --config GDAL_NUM_THREADS ALL_CPUS --config NUM_THREADS_OVERVIEW ALL_CPUS -ro zapad-warped-jxl.tif