Build Object Height Model (OHM) AWS Step Function

This step function postprocessing-build-ohm-step-function orchestrates the tiling, difference calculation, uploading and configuration of the Object Height Model (OHM). This layer is the difference between a DSM and DTM layer. These layers need to have the same dimensions. The function handles tiling based on a tile size. Uploading can be switched off if necessary.

Step functions

The step functions that are used within this step function:

• A PostprocessingRasterOptimization step function that generates the COG dataset.

Lambdas

The lambdas orchestrated by the Step function are the following:

• A UtilityGetPrefixFunction to generate the prefix used to find the input files and where data will be stored in S3.
• A UtilityTaskController generates payloads with input Parameters for the next Lambda Tasks.
• A PostprocessingBuildPropertiesFunction function to build properties files necessary for Geoserver coverage configuration.

./datastore.properties  # contains database schema information
./indexer.properties  # contains coverage information (EPSG)
./timeregex.properties  # contains regex string to determine date
./footprint.properties  # contains trigger for COG hosting

• A PostprocessingGetInstanceRequirements function to estimate EC2 resource requirements.
• A PostprocessingPublishRaster function to generate the publication information for Serverless infrastructure.
• A PostprocessingRunRasterCalc function to generate the publication information for Serverless infrastructure.
• A PostprocessingBuildRaster function call the Geoserver REST API to fullfill the ImageMosaic plugin generation. After this step the imagery should be visible online through Geoserver UI and front end WebApp.
• A PostprocessingBuildCache function calls the GeoWebCache API to start creating TileLayers and pre-seeding.

Invocation description

The following keys are required:

• job_id str - job id reference
• client_tag str - client tag to determine costing

The following keys are optional:

• legacy bool - prepare data for Geoserver of Serverless infrastructure, defaults to false.
• tilesize integer - pixel dimension size of output tiles. Defaults to 5000.
• upload bool - allow step function to upload to either infrastructure, defaults to true.
• options object - object, define all options or it will default to default options.
  • colours array - html colour codes. Defaults to Geoserver colour code set.
  • nodata number - overwriting the nodata value. Defaults to tile nodata.
  • si_unit str - measure unit used in the legend. Defaults to "m" for meters.

{
    "job_id": "n8732rh872g-1337-239hd923hd934hd9q3h438jf43932qd",
    "client_tag": "Some Client",
    "tilesize": 5000,
    "upload": true,
    "legacy": false
}