Disabling Accuracy Files for Datum Transforms

Spectrum Spatial supports conversions between certain datums by using algorithms that help shift coordinates more accurately. A separate jar file that contains these algorithms is installed by default for each datum transform located in the Spectrum Installation Location\server\types directory:

  • midev-core-coordsys-irishtm-version number-onprem.jar for Irish Transverse Mercator
  • midev-core-coordsys-jgd2000-version number-onprem.jar (also enables the updated version, JGD2011) for Japanese datums
  • midev-core-coordsys-nadcon-version number-onprem.jar for US Nad27-Nad83
  • midev-core-coordsys-ntv2-version number-onprem.jar for NTV2, which contains multiple conversions for many countries.
    Note: An XML file inside this jar controls which conversions are in use. To disable specific conversions within that file, stop the server and extract the XML file from the jar. Use an editor to set the entries to "false" for each conversion you want to disable. Add the edited XML file back into the jar, then restart the server. Similarly, if you want to enable the conversion, set the entries to true. For details see Enabling NTv2 Transform.
  • midev-core-coordsys-rgf93-version number-onprem.jar for French Lambert conversions

By default, all of these jar files are loaded; however, their use can negatively affect the performance of certain operations. These conversions can be disabled in some cases, such as when you do not require a certain type of conversion (for example, if you have no need to convert Japanese datums) or the performance gains outweigh the benefits of accuracy at lower zoom levels.

To disable a specific transform:

  1. Stop the server.
  2. Remove the jar from the directory. Alternatively, you can rename the jar file to have a different extension (for example, .jar~) which will prevent it from being loaded.
  3. Restart the server.