stamen / mpg-marblecutter-virtual

Virtual catalogs for marblecutter

mpg-marblecutter-virtual

Originally based on marblecutter-virtual.

I am a tile server for HTTP(S)-accessible Cloud Optimized GeoTIFFs (COGs).

I can also be seen as an example of a virtual Catalog implementation, drawing necessary metadata from URL parameters. For more information, check out VirtualCatalog and web.py.

Running Locally

The easiest way to get a working instance running locally is to use Docker Compose:

docker-compose up

A tile server will then be accessible on localhost:8000. To browse a map preview, visit http://localhost:8000/preview?url=https%3A%2F%2Fs3.amazonaws.com%2Ftiles.mpgranch.com%2Fsources%2F2017c_jan18clip_cloudoptimized.tif

URLs (url in the query string) must be URL-encoded. From a browser's JavaScript console (or Node.js REPL), run:

encodeURIComponent("https://s3.amazonaws.com/tiles.mpgranch.com/sources/2017c_jan18clip_cloudoptimized.tif")

If you need to access non-public files on S3, set your environment accordingly (see sample.env), either by creating .env and uncommenting env_file in docker-compose.yml or by adding appropriate environment entries.

Endpoints

/bounds - Source image bounds (in geographic coordinates)

Parameters

• url - a URL to a valid COG. Required.

Example

$ curl "http://localhost:8000/bounds?url=http://localhost:8000/preview?url=https%3A%2F%2Fs3.amazonaws.com%2Ftiles.mpgranch.com%2Fsources%2F2017c_jan18clip_cloudoptimized.tif"
{
  "bounds": [
    -114.0598676519122,
    46.65466452757754,
    -113.9039579851515,
    46.78638812429985
  ],
  "url": "https://s3.amazonaws.com/tiles.mpgranch.com/sources/2017c_jan18clip_cloudoptimized.tif"
}

/tiles/{z}/{x}/{y} - Tiles

Parameters

• url - a URL to a valid COG. Required.
• rgb - Source bands to map to RGB channels. Defaults to 1,2,3.
• nodata - a custom NODATA value.
• linearStretch - whether to stretch output to match min/max values present in the source. Useful for raw sensor output, e.g. earth observation (EO) data.
• resample - Specify a custom resampling method (e.g. for discrete values). Valid values (from rasterio.enums.Resampling): nearest, bilinear, cubic, cubic_spline, lanczos, average, mode, gauss, max, min, med, q1, q3. Defaults to bilinear.

@2x can be added to the filename (after the {y} coordinate) to request retina tiles. The map preview will detect support for retina displays and request tiles accordingly.

PNGs or JPEGs will be rendered depending on the presence of NODATA values in the source image (surfaced as transparency in the output).

Examples

$ curl "http://localhost:8000/tiles/14/3851/6812@2x?url=https%3A%2F%2Fs3.amazonaws.com%2Ftiles.mpgranch.com%2Fsources%2F2017c_jan18clip_cloudoptimized.tif" | imgcat

$ curl "http://localhost:8000/tiles/14/3851/6812@2x?url=https%3A%2F%2Fs3.amazonaws.com%2Ftiles.mpgranch.com%2Fsources%2F2017c_jan18clip_cloudoptimized.tif&rgb=1,1,1" | imgcat

$ curl "http://localhost:8000/tiles/14/3851/6812@2x?url=https%3A%2F%2Fs3.amazonaws.com%2Ftiles.mpgranch.com%2Fsources%2F2017c_jan18clip_cloudoptimized.tif&rgb=1,1,1&linearStretch=true" | imgcat

/tiles - TileJSON

Parameters

See tile parameters.

Example

$ curl "http://localhost:8000/tiles?url=https%3A%2F%2Fs3.amazonaws.com%2Ftiles.mpgranch.com%2Fsources%2F2017c_jan18clip_cloudoptimized.tif"
{
  "bounds": [
    -95.46993599071261,
    28.86905396361014,
    -95.2386152334213,
    29.068190805522605
  ],
  "center": [
    -95.35427561206696,
    28.968622384566373,
    15
  ],
  "maxzoom": 21,
  "minzoom": 8,
  "name": "Untitled",
  "tilejson": "2.1.0",
  "tiles": [
    "//localhost:8000/tiles/{z}/{x}/{y}?url=https%3A%2F%2Fs3.amazonaws.com%2Ftiles.mpgranch.com%2Fsources%2F2017c_jan18clip_cloudoptimized.tif"
  ]
}

/preview - Preview

Parameters

See tile parameters.

Example

http://localhost:8000/preview?url=https%3A%2F%2Fs3.amazonaws.com%2Ftiles.mpgranch.com%2Fsources%2F2017c_jan18clip_cloudoptimized.tif

Deploying to AWS

marblecutter-virtual is deployed using the AWS Serverless Application Model (SAM).

Once you have the SAM CLI installed, you can build with:

sam build --use-container

You can then test it locally as though it's running on Lambda + API Gateway (it will be really slow, as function invocations are not re-used in the same way as on Lambda proper):

sam local start-api

To deploy, first package the application:

sam package --s3-bucket <staging-bucket> --output-template-file packaged.yaml

Once staged, it can be deployed:

sam deploy \
  --template-file packaged.yaml \
  --stack-name marblecutter-virtual \
  --capabilities CAPABILITY_IAM \
  --parameter-overrides DomainName=<hostname>

These commands are wrapped as a deploy target, so this can be done more simply with:

S3_BUCKET=<staging-bucket> DOMAIN_NAME=<hostname> make deploy

<staging-bucket> must be in the target AWS region (AWS_DEFAULT_REGION).

NOTE: when setting up a Cloudfront distribution in front of a regional API Gateway endpoint (which is what this process does), an Origin Custom Header will be added: X-Forwarded-Host should be the hostname used for your Cloudfront distribution (otherwise auto-generated tile URLs will use the API Gateway domain; CF sends a Host header corresponding to the origin, not the CDN endpoint).