GeoPackage overview
A key Carmenta Engine feature is that all data formats are read in their native format, processed internally and finally displayed. This makes it easy to use Carmenta Engine in desktop applications or server solutions since there is no need to convert data before it can be used. But it may be unsuitable for some mobile applications, where processing power and battery capacity of the devices is limited. Operations like projecting rasters from one coordinate reference system to another can decrease performance and increase power consumption.
Carmenta Engine provides a set of components that are meant to make it easier to deploy and efficiently use various sorts of geodata, on both mobile devices with limited processing power and in desktop applications and server solutions. This is done by packing geodata into an OGC GeoPackage, a single standalone data file that has been designed to be fast to read from. The GeoPackage is prepared with a spatial index so that a device does not have to index the data itself. Packing data into a single file will also make deployment easier.
Creating GeoPackages
The MapPackage class makes it possible to create and populate OGC GeoPackages from your own code.
OGC GeoPackage files can be created in Carmenta Explorer from any regular map configuration file. There is a tutorial that describes how you can use Carmenta Explorer to pack image data, coverage data and vector features into a single GeoPackage and how to display it. Please see GeoPackage Tutorial for more information.
Reading data from GeoPackage
Data in the OGC GeoPackage format is read with a MapPackageDataSet and further options can be specified by attaching a MapPackageQuery to a ReadOperator.
You can see the topographic_map_mappackage.px sample configuration for an example on how to create a configuration that uses this data set.