# Introduction¶

Django-raster provides high level utilities to work with raster data in Django. It is based on the Django internal GDALRaster object and RasterField datatype.

There are three main components in this package:

• Parser utility to ingest rasters through the admin or the django shell.
• Tile Map Service (TMS) endpoint to render raster data.
• Raster calculator to compute and render raster calculator expressions.

Raster files are stored in a file field attached to RasterLayer objects. Data can be added by creating raster layers through the admin interface or the Django shell.

After creating a RasterLayer object, the raster data will be parsed automatically. The parsing can be executed asynchronously if Celery is integrated into the Django project. The raster parser will automatically extract the data in the raster and store it as PostGIS raster tiles on the database.

After ingesting the data, raster styles can be defined through the admin interface which are then used to render the data through TMS endpoints. The endpoints can be used in Javascript mapping software such as OpenLayers or Leaflet.

## Limitations¶

The main limitation of the django-raster package is that it is focused on single band rasters. For most of the functionality, only the first band in the raster is used. While the tile parser processes and stores all bands of the input rasters, for the TMS endpoints and raster algebra calculations, currently only the first band is used.

Another limitation is that the projection of the raster tiles is fixed to the Web Mercator Projection (EPSG 3857). This is because a large part of online mapping applications use this projection, especially TMS services.