Reproject node

With geospatial or map data, two of the most common ways to identify coordinates are projected coordinate and geographic coordinate systems. In Watson Studio, items such as the Expression Builder spatial functions and the Spatio-Temporal Prediction (STP) node use the projected coordinate system. Therefore, any data you import that is recorded with a geographic coordinate system must be reprojected.

Where possible, geospatial fields (any fields with a geospatial measurement level) are automatically reprojected when used (not when they are imported). Where any fields cannot be reprojected automatically, you use the Reproject node to change their coordinate system. Reprojecting in this way means that you can correct situations where an error occurs due to use of an incorrect coordinate system.

Here are some example situations where you might have to reproject to change the coordinate system:

  • Append. If you try to append two data sets with different coordinate systems for a geospatial field, Watson Studio may display an error message such as: Coordinate systems of <Field1> and <Field2> are not compatible. Reproject one or both fields to the same coordinate system.

    <Field1> and <Field2> are the names of the geospatial fields that caused the error.

  • If/else expression. If you use an expression that contains an if/else statement with geospatial fields or return types in both parts of the expression, but with different coordinate systems, Watson Studio may display an error message such as: The conditional expression contains incompatible coordinate systems: <arg1> and <arg2>.

    <arg1> and <arg2> are the then or else arguments that return a geospatial type with different coordinate systems.

  • Constructing a list of geospatial fields. To create a list field that consists of numerous geospatial fields, all geospatial field arguments that are supplied to the list expression must be in the same coordinate system. If they aren't, then an error message such as the following may be displayed: Coordinate systems of <Field1> and <Field2> are not compatible. Reproject one or both fields to the same coordinate system.