mbtiles in MM

[jhpoosthoek]

Hello,

I would like to get MBTILES (www.mbtiles.org) working in MM. I created such a file using gdal2tiles.py (https://github.com/developmentseed/gdal2mb). Next I created a PHP script (sqlite reading from https://github.com/mapbox/mbutil/) which reads the correct PNG file from the MBTILES file. It is called in javascript and MM through: var provider = new MM.TemplatedMapProvider('http://localhost/mb2xyz.php?code={Z}/{X}/{Y}');

This however doesn't work perfectly, the more you zoom in the less of the northern hemisphere is visible. I was wondering if people might recognize this problem as something from MM. If not, I guess it might be my PHP script. The MBTILES file seems to work perfectly when I open it using Maps on a Stick (http://developmentseed.org/blog/2010/oct/02/maps-stick-version-2-released)

A MBTILES example can be downloaded here: http://mapbox.com/#/tileset/natural-earth-2

Cheers, Jelmer

---

<?php $xyz = $_REQUEST['code']; $xyz = explode("/", $xyz); header("Content-Type: image/png"); $z = $xyz[0]; $x = $xyz[1]; $y = $xyz[2]; $y = pow(2, $z-1) - $y; $mbtiles_file = "natural-earth-2.mbtiles"; $db = new PDO('sqlite:'.$mbtiles_file);

$pngdata = @$db->prepare('select tile_data from tiles where zoom_level = '.$z.' and tile_column = '.$x.' and tile_row = '.$y.';'); $pngdata->execute(); $pngdata = $pngdata->fetchObject(); $pngdata = $pngdata->tile_data; echo $pngdata; ?>

[shawnbot]

I'm confused by the munging of the Y values (pow(2, $z-1) - $y): doesn't MBTiles use the same spherical mercator coordinate system as MM? Invalid Y values would certainly explain more of the vertical world disappearing as you zoom in.

[RandomEtc]

MBTiles uses TMS coordinates which have the origin at the bottom left: http://wiki.osgeo.org/wiki/Tile_Map_Service_Specification

Perhaps $z = $z - 1 and $y = pow(2,$z) - $y would do the trick? In MM zoom level 0 is 1 tile, zoom level 1 is 2x2 tiles, etc, but I think in TMS zoom level 0 is 2x2.

[RandomEtc]

Or maybe $y = pow(2, $z) - 1 - $y - leaving $z as you had it? Sorry for random guesses, it's Friday night :)

[jhpoosthoek]

I changed: $y = pow(2, $z-1) - $y; for: $z = $z - 1; $y = pow(2, $z) - 1 - $y; and now it works, thanks!

The next issue I'm trying solve is to continue the map from the dateline onwards. I was able to fit the maps together by: if($x > 0) { $x = $x - 2; } if($x < 0) { $x = $x + 2; } But if you zoom in this creates all sorts of nasty behavior (lower resolution parts next to higher ones, it looks like a mess). Anyone a clue whats going on?

[springmeyer]

See the mapbox/wax code, specifically the connectors/mm which provides a customized getTile method to handle the y flip correctly. And then rest assured that mbtiles will switch to the osm/xyz scheme that mm uses soon to avoid the need for this y flip to TMS.

[jhpoosthoek]

Thanks! Am I correct to say that this code from waxconnector.js does what I need? return this.options.tiles[parseInt(Math.pow(2, coord.zoom) * coord.row + coord.column, 10) % this.options.tiles.length] .replace('{z}', coord.zoom.toFixed(0)) .replace('{x}', coord.column.toFixed(0)) .replace('{y}', coord.row.toFixed(0));

I haven't been able to get wax working yet (no examples found) so I figured I try to add what I need into my code.

[tmcw]

@jhpoosthoek have you seen the Wax manual? It's overflowing with examples.

[jhpoosthoek]

@tmcw, yes I've seen the manual before. I guess I'm used to little example htmls such as created for openlayers and MM. I didn't get the wax examples to work immediately, but now I see that the manual itself also uses wax ;) thanks.

[jhpoosthoek]

I got to it again and the problem is that the wax.mm.connector doesn't seem to work with my tiles: PHP url (the example tiles from mapbox.com on the other hand work perfectly): var tilejson = { tilejson: '1.0.0', scheme: 'tms', tiles: ['http://www.iivision.com/temp/mb2xyz.php?file=ne2&code={Z}/{X}/{Y}'] }; Anyone an idea why this doesn't seem to work?

[tmcw]

Hey, so is this the full natural-earth tileset? Regardless of TMS/XYZ, the url http://www.iivision.com/temp/mb2xyz.php?file=ne2&code=0/0/0 should resolve to a worldwide tile if so.

[jhpoosthoek]

@tmcw, yes it is. I commented out the following lines in the PHP: //$z = $z - 1; //$y = pow(2, $z) - 1 - $y; So now 0/0/0 shows the worldwide tile. But it still doesn't work...

[tmcw]

@jhpoosthoek - this seems to be working fine, are you actually using Wax? http://bl.ocks.org/1149162

[jhpoosthoek]

@tmcw, yes it works! Thanks! I downloaded wax from github, but somehow this just didn't work. The PHP also doesn't work on my localhost through XAMPP. But I don't mind, it works!

I'm working to get also other datasets in: http://www.iivision.com/temp/mb2xyz.php?file=mola&code={z}/{x}/{y}, but I guess I need to do a little bit of GDAL work before I can pass it through the gdal2mb script...

[tmcw]

Great!