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geotrellis / geotrellis-pointcloud

GeoTrellis PointCloud library to work with any pointcloud data on Spark
Apache License 2.0
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Add overview strategies for EPT hierarchy selection tuning #79

Closed jpolchlo closed 4 years ago

jpolchlo commented 4 years ago

The natural mode of operation of the DEM rasterizers is to target the EPT hierarchy level with the closest "cell size" to the requested RasterExtent. This will aim to satisfy the query with a return density of approximately one point per pixel. Sadly, this can lead to significant delays in serving queries, particularly when using TIN as the interpolation strategy.

We want to allow for the user to tune queries so that EPT hierarchy levels relative to the raster query can be selected instead. This would trade off accuracy for performance.

This PR addresses this need by allowing for an OverviewStrategy to be provided to control which level of the EPT tree is selected. This can be an absolute level, or a level relative to the raster cell size.

Closes #62

jpolchlo commented 4 years ago

This PR should be ready to go. In principle. The TIN sources have the overview strategies added in, but they've not been tested, since the procedure for adding this stuff in to geotrellis-pointcloud-server for visual inspection is a pain, and it's a fairly straightforward copy of the strategy code from the IDW sources. Proposing that we go through the validation procedure for this PR as is.

pomadchin commented 4 years ago

LGTM, works as expected! Merging and upgrading gt server to use the latest snapshot!