In early versions of gvSIG a support of CRS (Coordinate Reference System) was developed with basic functions and definitions. This implementation allows the user to select the reference system based on the datum, projection and time zone.
However it has some limitations when applying transformations. Besides it doesn’t support, for instance, the time zones from the southern hemisphere.
Then a new version was developed based on GeoTools and Proj4 libraries, with many more features, CRS definitions, even with the option to allow users to create their own CRS.
- While gvSIG is developed in Java language to allow the execution in multiple platforms, the usage of Proj4 which is a native library, lost that platform independence. Although Proj4 is available on multiple architectures and operating systems, it requires to generate different gvSIG installable for each of them. This increases the complexity and the maintenance of the gvSIG binaries.
- That new support uses a local database to query the CRS supported, and require the installation of the library Proj4, along with their dependencies. This involves higher resource requirements (memory and hard disk) than in the previous support.
gvSIG Association has also recently developed a new project focused on educational environments: gvSIG Educa. Within this project includes gvSIG Batoví, which is the distribution that gives rise to gvSIG Educa. This distribution is driven by the Ministry of Transport and Public Works (MTOP) of the República Oriental del Uruguay and developed by the gvSIG Association and the Faculty of Engineering of the Universidad de la República (UdelaR), and focuses on the use of a Geographic Information System in educational environments for the PlanCeibal (Uruguay).
It is a gvSIG 2.0 desktop distribution to be installed on computers OLPC. These computers have limited resources, so it is not viable to use the CRS-based on Proj4. On the other hand the use of basic support is not possible, lacking to manage the time zones from the southern hemisphere.
Alternatively it was developed a new CRS support, using for that purpose the Proj4J library, which is a partial implementation of Proj4 in Java language, and it is independent of the operative system in which gvSIG is installed.
Functionally it allows to choose the CRS based on the authority and code, providing support for large number of definitions.
This new support will be included on gvSIG Batoví distributions, as well as being available for installing on gvSIG Desktop 2.0 through the add-ons manager plugin.
In gvSIG Desktop 2.0 the three CRS implementations will be available. The basic implementation is included on gvSIG, and the other two can be installed as plugins. If the user install the three of them, the available one from the user interface will be Proj4. But if that one is not installed, the one that will be activated is the Proj4J one.