Combining OpenLayers raster and vector layers for cropping and masking

Openlayers contains the powerful feature which enables you to combine 2 (or more) raster layers using a custom function with access to the pixels of each layer.

As vector layers can also be rendered as raster using the renderMode:image, this can be used to implement client side cropping and/or masking based on any shape.

Slippy Tile Explorer

All the major raster map services use the same 'slippy map' tiling technique to create the grid of images. When dealing with map servers it can be useful to view them.

Here is my basic OpenLayers/OpenStreetMap implementation based around the ol.source.TileDebug and the OpenStreetMap implementation to calculate between coordinate and tile positions.

GeoHash Explorer

Geohashes provide a well tested method of parcelling the worlds surface into smaller and smaller discrete areas.

When dealing with geospacial data I often find myself returning to them as an elegant and simple technique of implementing searches against the data. There are enough articles out there on how they are created or how to use them for searching so I will not replicate those.