Library for generating terrain tiles in Cesium's quantized-mesh format from a GDAL raster file.

Requirements

This project depends on the following C++ libraries:

Boost (program_options): http://www.boost.org/
ZLib: https://www.zlib.net/
Cesium Terrain Builder (libctb): https://github.com/geo-data/cesium-terrain-builder
GDAL: http://www.gdal.org/
CGAL: https://www.cgal.org/
meshoptimizer: https://github.com/zeux/meshoptimizer (with small modifications, source included in this project)
JSON for modern C++: https://github.com/nlohmann/json (source included in this project)

Also, Python is required to run the scripts provided.

Compilation

This project uses the typical cmake pipeline. Thus, assuming that all the libraries listed above are installed, it should be as easy as:

mkdir build
cd build
cmake ..
make

Optionally, you can create the documentation using:

make doc

An already compiled version of the documentation can be found in the web of this project.

Usage

The main functionality of the project is provided by the qm_tiler app. A simple usage is:

qm_tiler -i <input_raster> -o <output_tiles_dir>

However, the method has many parameters that may be tuned, and that are explained in the tutorial. You can list them by running:

qm_tiler -h

After creating the TMS pyramid of tiles, use the script create_layer_file.py to create the layer.json file required by Cesium.

Finally, in order to easily test the project, we also provide the simple_tiles_server.py, which creates a simple web server of tiles.

Please refer to the tutorial page in the wiki of this project for further information.

Known issues

As previously stated, this project depends on Cesium Terrain Builder library (https://github.com/geo-data/cesium-terrain-builder), and thus it shares the same limitation when creating tiles at lower zoom levels from large DEMs. In this case, an error similar to the following one may raise:

ERROR 1: Integer overflow : nSrcXSize=20979, nSrcYSize=28800
ERROR 1: IReadBlock failed at X offset 0, Y offset 0
terminate called after throwing an instance of 'ctb::CTBException'

If the case above raises, you can use the provided qm_tiler_large_images.py python script, which basically automates the solution proposed in Cesium Terrain Builder's documentation (https://github.com/geo-data/cesium-terrain-builder).

Acknowledgements

This project has been developed by Coronis Computing S.L. within the EMODnet Bathymetry project.

EMODnet: http://www.emodnet.eu/
EMODnet (bathymetry): http://www.emodnet-bathymetry.eu/
Coronis: http://www.coronis.es