Extending Indicia to support new spatial systems¶
Indicia can support data entered as an x, y coordinate or in a local notation such as British National Grid or MTB. If an x, y coordinate system is required which is not one of the list supported in Indicia, then you will first need to know the EPSG code for your projection. You should be able to find this online. You can enter a comma separated list of EPSG codes into your Drupal IForm Settings page (under List of spatial or grid reference systems) or, on a form by form basis on the form’s edit tab under Other Map Setting > Allowed Spatial Ref Systems. This enables an option to use this projection when inputting coordinates (or clicking on the map) which is the bare minimum you’ll need to in order to submit records using your projection. Additional things you might like to do include:
- Edit the client_helpers/lang/default.php file to add a language string with the key epsg:nnnn where nnnn is your EPSG code. The language string provided will allow Indicia to show a sensible name for your projection rather than just a number.
- Edit the IForm module’s list of declared systems to add it to the IForm settings configuration page (iform.admin.inc in Drupal 7, Settings/Form/Settings.php in Drupal 8).
- The reprojection code used by Indicia will obtain the details for projections which it does not recognise from a remote online repository. However to reduce network traffic and improve reliability it is better to create a local definition. This can be added to media/js/proj4defs.js and the definitions themselves can be obtained from spatialreference.org.
Finally to support the projection properly on the warehouse, add the details required to application/config/sref_notations.php.
If you need to add a new grid reference notation then there is an additional task to write scripts which translate the notation to and from