mapsgeek / raster-to-mbtiles

Documentation on how process large rasters to converting them into MbTiles format.

Creating Raster MBTiles from GeoTiff

There are a few options for creating Raster MBTiles which include TileMill, Gdal2Mbtiles, and Mapbox Studio Classic. That said, we have been most successful by prepping the images first in QGIS and then using gdal translate to create the tiles.

If the raster image file is small enough, it may be possible to upload it directly to mapbox studio without first creating a '.mbtile' file, however the allowable size is quite small and you have a more limited ability to style the map.

Primary Method: QGIS Image Preperation + GDAL Translate

1. Setting up Python Environment

First, prior to using GDAL, it may be necessary to create a python2.7 environment. You can read about setting up environments here. This will take a few minutes as it may need to install necessary packages.

conda create -n python2 python=2.7 anaconda

You can activate the environment you just created by running:

source activate python2

Whenever you need to leave this environment, you can simply run source deactivate.

Install gdal.

conda install gdal

GDAL (Geospatial Data Abstraction Library) is an open source tool which is incredibly helpful for spatial data transformations.

2. Image Preparation Stage:

Before preforming the translation into MBTiles it is often helpful to first prepare the image in some GIS software (we used QGIS). Without this, we ran into some problems where gdal_translate oversimplified the gradient in the original image and did not account for 'no value' regions.

In our case, we used QGIS to do the following:

Add color

To do this, start by dragging a raster file (generally either '.adf' or '.tif' file) into QGIS Layers Panel. This should present an image of your map.

From here, we can alter the image properties by right clicking on the layer name and going to 'properties'. Often, the Render Type is set to 'Singleband Gray', but we can add color by changing that to 'Singleband pseudocolor' and select a Color that fits the map (QGIS comes with some great default color gradient options). This also often takes care of inverted color scales (where darker regions are actually lower values) - if this is not the case, you can 'invert' using the checkbox to the right of the color selection.

Change/Ensure Projection and Save as Rendered Image (GTiff)

At this point, we can save our changes using the Save as option.

Here, it is important to make sure to select 'Rendered Image' and the correct projection for your map. For all of our maps, we used EPSG:4326 - WGS 84.

2. gdal_translate

From here it is incredibly quick to create mbtiles from your final map. Make sure you are in your python2 environment by running source activate python2 and then simply run the following:

gdal_translate geoTiff_raw.tif output.mbtiles -of MBTILES
# to create multiple zoom layers, you can then run
gdaladdo -r average output.mbtiles 2 4 8 16

(taken from the bottom of gdal's mbtile page)

This should now be easy to import as a shiny new tileset to Mapbox Studio.

Helpful Hint: At any stage you can run gdalinfo [filename] to view the metadata of the current file (such as information about zoom levels and color bands).

In some cases you may need to first create a mask, but if you prepared the image in QGIS, this should be less of an issue.

# OR first create mask of image
gdal_translate geoTiff_raw.tif -b mask out.tif
gdal_translate out.tif out.mbtiles -of MBTILES

Alternate Approaches

1. TileMill

TileMill is a precursor to Mapbox Studio online. Though not in active development, it has shifted to an open open source contributor model.

Raw GeoTiff File

GeoTiff Rendered Output Export from QGIS

Get TileMill here If it is unable to open (problem on MacOS) check out this issue.

2. gdal2mbtiles

Converts GDAL readable datasets into an MBTiles file

Get gda2mbtiles here

Make sure gdal is installed here first as a dependency for gdal2mbtiles

source activate python2
conda install gdal
pip install gdal2mbtiles
# Verify Installation
gdal2mbtiles --help

gdal2mbtiles -v --min-resolution 4 --max-resolution 12 geoTiff_raw.tif geoTiff_raw.mbtiles

3. rio-mbtiles

A plugin for the Rasterio CLI that exports a raster dataset to the MBTiles (version 1.1) format. Features include automatic reprojection and parallel processing. This method requires that the raster maps have color tables, which wasn't the case for many of our initially greyscale maps.

Get rio-mbtiles here

Other Alternatives (we haven't tested these yet)

• Kosmtik
• TileOven

References

Adding a color table to one band Tiff

For problems installing gdal on Mac this may be helpful.