Improve doc of proj_coordoperation_get_towgs84_values() (fixes #1430)

OSGeo · Apr 18, 2019 · ed20821 · ed20821
1 parent 7c36ca4
commit ed20821
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/src/iso19111/c_api.cpp b/src/iso19111/c_api.cpp
@@ -5985,7 +5985,10 @@ int proj_coordoperation_get_param(
  * @param coordoperation Object of type Transformation, that can be represented
  * as a WKT1 TOWGS84 node (must not be NULL)
  * @param out_values Pointer to an array of value_count double values.
- * @param value_count Size of out_values array.
+ * @param value_count Size of out_values array. The suggested size is 7 to get
+ * translation, rotation and scale difference parameters. Rotation and scale
+ * difference terms might be zero if the transformation only includes translation
+ * parameters. In that case, value_count could be set to 3.
  * @param emit_error_if_incompatible Boolean to inicate if an error must be
  * logged if coordoperation is not compatible with a WKT1 TOWGS84
  * representation.