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tatry

Fast and simple Elevation API server.

Install

``sh
$ npm --global install tatry
`

tatry requires dataset to work. Please refer to [open-elevation] project on how to download and prepare the dataset.
tatry only works with regular TIFF files, uncompressed with elevation data kept as Int32 pixels.

You can use gdal_translate to convert your data.

`sh


to decompress TIFF

gdal_translate -co "COMPRESS=none" in.tif out.tif

to convert data to Int16 per pixel

gdal_translate -ot Int16 -strict in.tif out.tif
`

You may need to [split large][split-tiles] (>4GB) files into smaller parts since tatry does not support BigTIFF file format.

Data does not have to cover contiguous area. Where tatry finds a point that is represented by multimple tiles it will attempt to use the highest resolution data. Results are automatically interpolated using [bilinear interpolation].

Configuration

The following environment variables can be specified:

- TATRY_PORT - port on which server listens - defaults to 3080
- TATRY_DATA_PATH - location of .tif files - defaults to /var/lib/tatry
- TATRY_WORKERS - number of workers threads - defaults to 2
- TATRY_CACHE_SIZE - size of the .tif tile cache, the bigger it is the more .tif info will be kept in memory - defaults to 100mb

tatry will initialize its environment from /etc/default/tatry file

API

$3

#### GET /api/v2/lookup?lls=lon_1,lat_1|lon_2,lat_2

Looks up elevation for one or more points. Each point is specified as longitude,latitude pair (think x,y).
Points are separated with |.

Example:

/api/v2/lookup?lls=-160,30|100,-45

Result is return as JSON and contains a single results property which is an array of { ll, elevation } tuples.

`json
{
"results": [
{
"ll": [ -160, 30 ],
"elevation": 100
},
{
"ll": [ 100, -45 ],
"elevation": -3.5
}
]
}
`

#### POST /api/v2/lookup

Looks up elevation for one or more points. Parameters are sent in JSON body. lls parameter contains an array
of longitude,latitude pairs.

`json
{
"lls": [
[ -160, 30 ],
[ 100, -45 ]
]
}
`

Result is the same as GET` request result.

$3

V1 API is compatible with [open-elevation] API - click for [details][open-elevation-api]

Acknowledgments

Big thank you to João Ricardo Lourenço A.K.A @Jorl17 and @Developer66 for their work on [open-elevation] project.

License

MIT © Damian Krzeminski

[split-tiles]: https://github.com/mapbox/gdal-polygonize-test/blob/master/split.sh
[bilinear interpolation]: https://en.wikipedia.org/wiki/Bilinear_interpolation

[open-elevation]: https://github.com/Jorl17/open-elevation
[open-elevation-api]: https://github.com/Jorl17/open-elevation/blob/master/docs/api.md

[npm-image]: https://img.shields.io/npm/v/tatry
[npm-url]: https://npmjs.org/package/tatry

[build-url]: https://github.com/mapwhit/tatry/actions/workflows/check.yaml
[build-image]: https://img.shields.io/github/actions/workflow/status/mapwhit/tatry/check.yaml?branch=main

[deps-image]: https://img.shields.io/librariesio/release/npm/tatry
[deps-url]: https://libraries.io/npm/tatry