| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.sis.referencing.operation.provider; |
| |
| |
| /** |
| * The method to use for applying a datum shift. |
| * Values are ordered from most accurate method to less accurate. |
| * This enumeration does not include datum shift based on grid files. |
| * |
| * @author Martin Desruisseaux (Geomatys) |
| */ |
| public enum DatumShiftMethod { |
| /** |
| * Transformation in geocentric domain (translation or position vector 7-parameters). |
| */ |
| GEOCENTRIC_DOMAIN, |
| |
| /** |
| * Approximation of geocentric translations. |
| */ |
| MOLODENSKY, |
| |
| /** |
| * Approximation of Molodensky transformations, |
| * which is itself an approximation of geocentric translations. |
| */ |
| ABRIDGED_MOLODENSKY, |
| |
| /** |
| * No datum shift applied (not even a change of ellipsoid). |
| * This method should be used only when a coarse accuracy (at least 3 km) is sufficient. |
| */ |
| NONE; |
| |
| /** |
| * Suggests an operation method for the given accuracy. This method contains accuracy threshold (in metres) |
| * for allowing the use of Molodensky approximation instead of the Geocentric Translation method. |
| * The accuracy of datum shifts with Molodensky approximation is about 5 or 10 metres. |
| * However for this method, we are not interested in absolute accuracy but rather in the difference |
| * between Molodensky and Geocentric Translation methods, which is much lower (less than 1 m). |
| * We nevertheless use a relatively high threshold as a conservative approach. |
| * |
| * @param desired desired accuracy on Earth (metres). |
| * @return suggested datum shift method for an accuracy equals or better than the given value. |
| * |
| * @see <a href="https://issues.apache.org/jira/browse/SIS-369">SIS-369</a> |
| */ |
| public static DatumShiftMethod forAccuracy(final double desired) { |
| if (desired >= 5) { |
| return MOLODENSKY; |
| } else { |
| return GEOCENTRIC_DOMAIN; |
| } |
| } |
| } |