From commits-return-10276-apmail-sis-commits-archive=sis.apache.org@sis.apache.org Sun Jan 28 17:52:06 2018 Return-Path: X-Original-To: apmail-sis-commits-archive@www.apache.org Delivered-To: apmail-sis-commits-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 988D017D56 for ; Sun, 28 Jan 2018 17:52:06 +0000 (UTC) Received: (qmail 64553 invoked by uid 500); 28 Jan 2018 17:52:06 -0000 Delivered-To: apmail-sis-commits-archive@sis.apache.org Received: (qmail 64524 invoked by uid 500); 28 Jan 2018 17:52:06 -0000 Mailing-List: contact commits-help@sis.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: sis-dev@sis.apache.org Delivered-To: mailing list commits@sis.apache.org Received: (qmail 64515 invoked by uid 99); 28 Jan 2018 17:52:06 -0000 Received: from pnap-us-west-generic-nat.apache.org (HELO spamd4-us-west.apache.org) (209.188.14.142) by apache.org (qpsmtpd/0.29) with ESMTP; Sun, 28 Jan 2018 17:52:06 +0000 Received: from localhost (localhost [127.0.0.1]) by spamd4-us-west.apache.org (ASF Mail Server at spamd4-us-west.apache.org) with ESMTP id 00EAAC0033 for ; Sun, 28 Jan 2018 17:52:06 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at spamd4-us-west.apache.org X-Spam-Flag: NO X-Spam-Score: -110.311 X-Spam-Level: X-Spam-Status: No, score=-110.311 tagged_above=-999 required=6.31 tests=[ENV_AND_HDR_SPF_MATCH=-0.5, RCVD_IN_DNSWL_MED=-2.3, SPF_PASS=-0.001, T_RP_MATCHES_RCVD=-0.01, USER_IN_DEF_SPF_WL=-7.5, USER_IN_WHITELIST=-100] autolearn=disabled Received: from mx1-lw-eu.apache.org ([10.40.0.8]) by localhost (spamd4-us-west.apache.org [10.40.0.11]) (amavisd-new, port 10024) with ESMTP id x0ekz33w0fvX for ; Sun, 28 Jan 2018 17:52:01 +0000 (UTC) Received: from mailrelay1-us-west.apache.org (mailrelay1-us-west.apache.org [209.188.14.139]) by mx1-lw-eu.apache.org (ASF Mail Server at mx1-lw-eu.apache.org) with ESMTP id 25B9F60EC8 for ; Sun, 28 Jan 2018 17:52:01 +0000 (UTC) Received: from jira-lw-us.apache.org (unknown [207.244.88.139]) by mailrelay1-us-west.apache.org (ASF Mail Server at mailrelay1-us-west.apache.org) with ESMTP id 4EF73E00B0 for ; Sun, 28 Jan 2018 17:52:00 +0000 (UTC) Received: from jira-lw-us.apache.org (localhost [127.0.0.1]) by jira-lw-us.apache.org (ASF Mail Server at jira-lw-us.apache.org) with ESMTP id 0590121300 for ; Sun, 28 Jan 2018 17:52:00 +0000 (UTC) Date: Sun, 28 Jan 2018 17:52:00 +0000 (UTC) From: "Martin Desruisseaux (JIRA)" To: commits@sis.apache.org Message-ID: In-Reply-To: References: Subject: [jira] [Created] (SIS-390) When datum shift information are missing, still apply ellipsoid change MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-JIRA-FingerPrint: 30527f35849b9dde25b450d4833f0394 Martin Desruisseaux created SIS-390: --------------------------------------- Summary: When datum shift information are missing, still apply= ellipsoid change Key: SIS-390 URL: https://issues.apache.org/jira/browse/SIS-390 Project: Spatial Information Systems Issue Type: Improvement Components: Referencing Affects Versions: 0.7 Environment: For some pairs of CRS, the datum is not the same but = Apache SIS is nevertheless unable to apply the datum change, either because= we didn't found explicit information in EPSG geodetic database, or because= the datum shift depends on a grid file that we don't have. The problem is = what to do in such case? Apache SIS 0.7 did nothing. Apache SIS 0.8 takes a= t least the change of ellipsoid in account. Example: EPSG:4609 =E2=80=94 _NAD27(CGQ77)_ uses the Clarke 1866 ellipsoid,= which is different than the WGS 84 ellipsoid. The coordinate operation fro= m that CRS to EPSG:4326 is [EPSG:1691|http://epsg-registry.org/?display=3De= ntity&urn=3Durn:ogc:def:coordinateOperation:EPSG::1691]. That operation req= uires the {{CGQ77-98.gsb}} datum shift file, which may not be installed. In= absence of datum shift information, an ellipsoid change can still be appli= ed using a Molodensky operation with all geocentric translation parameters = left to zero. This can be seen in the following fragment in the {{MathTrans= form}} WKT (this fragment is absent if the transform does nothing about the= datum/ellipsoid change). Note there is a change of 69 meters in the semi-m= ajor axis length and 169 meters in the semi-minor axis length: {noformat} Param_MT["Abridged Molodensky", Parameter["dim", 2], Parameter["src_semi_major", 6378137.0, Unit["metre", 1]], Parameter["src_semi_minor", 6356752.314245179, Unit["metre", 1]], Parameter["tgt_semi_major", 6378206.4, Unit["metre", 1]], Parameter["tgt_semi_minor", 6356583.8, Unit["metre", 1]], Parameter["X-axis translation", 0.0, Unit["metre", 1]], Parameter["Y-axis translation", 0.0, Unit["metre", 1]], Parameter["Z-axis translation", 0.0, Unit["metre", 1]], Parameter["Semi-major axis length difference", 69.4, Unit["metre", 1]], Parameter["Flattening difference", 3.726463918114448E-5, Unit["unity", 1]= ]] {noformat} Apache SIS conservatively reports an "accuracy" of 3 km when there is no da= tum shift operation, no matter if we nevertheless applied an ellipsoid chan= ge or not. Reporter: Martin Desruisseaux Assignee: Martin Desruisseaux Fix For: 0.8 -- This message was sent by Atlassian JIRA (v7.6.3#76005)