# GeoPlatform Tilegarden

## MVT Tiles

MVT tiles are a vector tile format, meaning geospatial data is represented as points, lines, and polygons in their native mathematical representation.

Advantages include
 - Their display can be customized client-side
 - Clients can run geospatial or geometric operations

Disadvantages include
 - Complex layers can take a long time to render and hog a lot of memory on the client

## Raster Tiles  

Raster tiles are images. precomputed to a level of detail at a particular zoom level

Advantages include
 - Lightweight rendering
 - Rendering speed and weight is unaffected by layer complexity

Disadvantages are 
 - Harder to customize the display on the client
 - More disk space is required for pre-computed tiles

## GeoPlatform Tilegarden

Both MVT and raster tiles (as PNG files) are rendered using [AWS lambda](https://aws.amazon.com/lambda/).  Tiles are cached in [AWS S3](https://aws.amazon.com/s3/) and can be precached for some higher zoom levels.

## Usage

See [GeoPlatform's TerriaMap](https://terriamap.geoplatform.gov/) for an example of how raster tiles are used.

A list of available cached services in GeoPlatform are available here: https://www.geoplatform.gov/search?filters=format:%7C:GeoPlatform%20Services Anything marked with "Vector Tile Service" or "Raster Tile Service" is availble for preview with TileGarden tiles

Raster tiles from cached services can be used in QGIS. For example "https://tileservice.geoplatform.gov/tile/7670d620_0a7d_4c2d_b5e7_884d8deddf43/{z}/{x}/{y}.png" can be added as an XYZ Tile layer.
## Data Updates

When data are updated, new cached layers are created, which will change the identifier in the URL.  There is currently no permalink available, so check back in GeoPlatform for any updated cache services.