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Maps

TODO

Add section on configuring tileserver-gl with json file to serve multiple tilesets and to serve vector tiles.

Mole includes a service that serves map tiles using tileserver-gl. To serve an set of map tiles in the .mbtiles format, place the file in the maps/maptiles folder.

Note

The .mbtiles file must have the name and format metadata tables set. See the .mbtiles spec for more information. The instructions below describe adding the appropriate metadata.

The tiles will be served at 

http://localhost/maps/data/<filename_without_extension>/<z>/<y>/<x>.jpg

A map preview is served at 

http://localhost/maps/data/<filename_without_extension>

The maps service runs by default. To disable it, use the --nomaps flag to ./ml run:

./ml run --nomaps

Generating Aerial Imagery Map Tiles

This section describes methods for obtaining aerial imagery and processing it into an .mbtiles file to be served by the Mole map tile server.

Acquiring Aerial Imagery

Digital Globe Imagery (preferred method)

Government employees can get access to Digital Globe imagery. This generally provides more recent data than that available via the NGA national map site. If you have access to Digital Globe, log in at https://evwhs.digitalglobe.com .
Here you can select a region of interest to download.

  1. Define an area of interest with the drawing tool.
  2. Select Generate a tileset
    1. Enter Name
    2. Set "End Zoom Level" to 18
  3. Click <Save>
  4. Files will be available under My Imagery --> Library once they have been prepared (takes a while)
  5. Uncompress the archive

National Map Imagery (method 2)

Go to http://viewer.nationalmap.gov/basic/ to download imagery for region of interest.

  1. Select "Imagery - 1 foot (HRO)" at the left
    1. Zoom to desired bounding box
    2. Click the black square icon
    3. Draw desired bounding box.
    4. Click the "Find Products" button at the top of the left pane.
      1. You can add additional search options (e.g. "CL" for only 3 band color imagery or "4B" for 4 band color imagery)
  2. Add all items to the card by pressing the "+All" icon for each page in the search returns
    1. This is tedious. Please update this page if you find a better way.
  3. Click "View Cart"
  4. Click "List and Export Cart Items"
    1. This will spawn a file download that corresponds to a .csv file with download links and information about each of the requested images.
  5. Download the files in the .csv file by either using the download manager (java program)
  6. Unzip all downloaded files.
    1. This should result in a set of .jp2 files.

Processing Imagery into .mbtiles

Digital Globe Imagery

The archive downloaded above already has a tiled structure. We just need to create an mbtiles file. The mbutil utility can do this.

  1. Install mbutil
    1. git clone http://github.com/mapbox/mbutil.git
  2. Change directory to the base of the Digital Globe tileset
    1. Sub-directories at this level should be numbers (e.g., /12/)

  3. Create metadata.json file:

    echo '{"name": "<desired_tileset_name>", "format": "jpg"}' > metadata.json

  4. Create the .mbtiles file:

    mbutil/mb-util --image_format=jpg ./ <filename>.mbtiles

National Map Imagery (method 2)

  1. In the folder containing the downloaded .jp2 files, run the following commands:
    1. gdalbuildvrt index.vrt *.jp2
    2. gdalwarp -r near --config GDAL_CACHEMAX 3000 -wm 3000 -co compress=jpeg -co photometric=ycbcr -co tiled=yes -t_srs EPSG:3857 index.vrt <filename>.tif
      1. see http://www.gdal.org/gdalwarp.html for more options, particularly for the resampling method (-r flag)
    3. gdaladdo -r nearest --config COMPRESS_OVERVIEW JPEG --config PHOTOMETRIC_OVERVIEW YCBCR <filename>.tif 2 4 8 16 32 64 128
      1. see http://www.gdal.org/gdaladdo.html for more options, particularly for the resampling method (-r flag)
  2. Use gdal2tiles.py to cut the tiles.
    1. Install gdal2tiles.py
      1. sudo apt-get install python-gdal
    2. gdal2tiles.py <filename>.tif
      1. This will create a folder called with appropriate tiles in it
  3. Use mbutil to create the mbtiles file
    1. Install mbutil
      1. git clone http://github.com/mapbox/mbutil.git
    2. ./mbutil/mb-util --scheme=tms <filename>/ <filename>.mbtiles