Custom tiles projection in WMTS

[daliborjanak]

Will be done in branch customtiles. Allow tileserver to use new metadata.json from MapTiler with informations about tilematrix set and serve it trought WMTS standart

[daliborjanak]

Now we have first usable results. Here is export from QGIS:

Layers:
Retro (maps.klokantech) as baselayer (EPSG:3857)
Swiss geography - rendered with MT and added in Swiss national crs EPSG:2056
Czech republic trains - rendered with MT in EPSG:5514

All layers warped displayed in QGIS in WGS84. Works well on all zoomlevels

Sample: http://labs.klokantech.com/tileserver/wmts

[daliborjanak]

Rendered GB national EPSG:27700, displayed in WGS84

[klokan]

It looks really cool @daliborjanak. Great job! Thank you. Looking forward to review and test the implementation!

[daliborjanak]

Implementation is done (see PR). Tileserver can now serve tiles in custom projections. It excepts definition of tilematrixset in metadata JSON file. It is triggered when "profile" has value "custom". If some definitions are missing, than tileserver tries to compute missing params as much as it can (method $Wmts->parseTileMatrix($layer, $tileMatrix)). Additional computations could be added in future e.g. scaleDenominator:

$crs = 'EPSG:5514';
$tile_size = [256, 256];
$extent = [-951499.37, -1276279.09, -159365.31, -983013.08];
$origin = [$extent[0], $extent[3]];
$pixel_size = [];

//constants
$StandardizedRenderingPixelSize = 0.00028; //defined in WMTS standart
$metersPerUnit = 1; //defined in proj def

/* Tile at zoom 0 */
// Coordinates always negative
$pixel_size[0] = abs(($extent[0] - $extent[2]) / $tile_size[0]);
echo 'Pixel size in M: ' . $pixel_size[0] . PHP_EOL;

// Scale denominator (derivated from WMTS equation:
// pixelSpan = scaleDenominator × 0.28 10 -3 / metersPerUnit(crs))  
$scaleDenominator = ($pixel_size[0] * $metersPerUnit) / $StandardizedRenderingPixelSize;
echo 'ScaleDenominator: ' . $scaleDenominator . PHP_EOL;

The metadata JSON schema example:

{
  "name": "swiss",
  "version": "1.1.0",
  "description": "",
  "type": "overlay",
  "format": "png",
  "minzoom": "0",
  "maxzoom": "5",
  "bounds": [5.85379955, 45.73743083, 10.66445076, 47.92094704], // in WGS84
  "scale": "1",

  "profile": "custom",
  "crs": "EPSG:2056",
  "proj4": "+proj=somerc +lat_0=46.95240555555556 +lon_0=7.439583333333333 +k_0=1 +x_0=2600000 +y_0=1200000 +ellps=bessel +towgs84=674.374,15.056,405.346,0,0,0,0 +units=m +no_defs ",
  "extent": [2476632.56374451, 1066330.29363826, 2841065.95706109, 1312791.87866593], // in projected coords
  "tile_matrix": [
  {
    "id": "0",
    "tile_size": [256, 256],
    "origin": [2476632.56374451, 1312791.87866593], //topleft corner of tilematrix
    "extent": [2476632.56374451, 1066330.29363826, 2841065.95706109, 1312791.87866593],
    "pixel_size": [1423.56794264, -1423.56794264], //size of pixel in projection units
    "scale_denominator": 5084171.22372462 // def in OGC WMTS spec
  },
  {
    "id": "1",
    "tile_size": [256, 256],
    "origin": [2476632.56374451, 1312791.87866593],
    "extent": [2476632.56374451, 1066330.29363826, 2841065.95706109, 1312791.87866593],
    "pixel_size": [711.78397132, -711.78397132],
    "scale_denominator": 2542085.61186231
  },
  {
    "id": "2",
    "tile_size": [256, 256],
    "origin": [2476632.56374451, 1312791.87866593],
    "extent": [2476632.56374451, 1066330.29363826, 2841065.95706109, 1312791.87866593],
    "pixel_size": [355.89198566, -355.89198566],
    "scale_denominator": 1271042.80593115
  }
...
]
}

[klokan]

Really cool! Can we get this to wmts.maptiler.com please?
It would make it directly applicable for people using MapTiler 0.6.4+.

[klokan]

Custom tiles branch merged to master in #71. Closing. If something is missing reopen.

Thank you @daliborjanak