Re: [Qgis-user] Re: Projection of Shapefile export

[Roland Hill]

Brett / All, I had a go at changing the AGD66 and AGD84 definitions in the QGIS database (srs.db) to include the towgs84 parameters and it appears to have worked. The attached image shows the same point assigned to GDA94, AGD66 and AGD84 with the offsets as expected. The updated srs.db can be found at http://dl.dropbox.com/u/9546967/srs.db if you would like to use it. The new srs.db was generated by running the following queries on srs.db in SQLite Database Browser UPDATE tbl_srs set parameters=replace(parameters, '+ellps=aust_SA', '+a=6378160 +rf=298.250000000055 +towgs84=-117.763,-51.51,139.061,-0.292,-0.443,-0.277,-0.191') where description like 'AGD84%' UPDATE tbl_srs set parameters=replace(parameters, '+ellps=aust_SA', '+a=6378160 +rf=298.250000000055 +towgs84=-129.193,-41.212,130.73,-0.246,-0.374,-0.329,-2.955') where description like 'AGD66%' Not sure how this compares to Ken and Giovanni's method. Cheers, Roland -- ROLAND HILL Director Four Winds Technology Pty Ltd Ph/Fax :  +61 (0)2 6366 9425 Mobile :  +61 (0)41 880 7472 roland.h...@fourwindstechnology.com.au Privacy and Confidentiality Notice The information contained herein and any attachments are intended solely for the named recipients. It may contain privileged confidential information. If you are not an intended recipient, please delete the message and any attachments then notify the sender of miss-delivery. Any use or disclosure of the contents of either is unauthorised and may be unlawful. All liability for viruses are excluded to the fullest extent permitted by law. On 23/09/10 15:47, Brett Adams wrote:  Ken, That's a legendary effort if your getting sensible results with the icsm files.  Do you think the format is suitable that it could be used in a sponsored bug fix? I gave this a shot myself but couldn't get it run at all, but then I have no idea what I'm doing so thats no real indication. I've had no success in getting parameters to stick (AGD66, AGD84 or GDA94) on shape or mapinfo files. Following solution was proposed by Roland Hill (22/09/2010  8:59pm) If your Custom CRS database does not appear to be working properly (ie you can see your custom CRS, but it isn't sticking to your data properly), then try to find your custom CRS database (qgis.db in your home directory on Linux, I guess it is in Application Settings or something similar in Windows) and delete it in case you have an old one with an incorrect format. Brett On 23/09/2010 12:47 PM, Ken Norris wrote: As Micha suggested, the National AGD66 distortion grid at http://www.icsm.gov.au/icsm/gda/gdatm/national66.zip and AGD84 distortion grid at http://www.icsm.gov.au/icsm/gda/gdatm/national84.zip seem to be the way forward. When unzipped, put into the proj directory (for me usr/share/proj) and coupled via the +nadgrids= parameter in a Custom CRS, it seems to yield the correct transform when tested. +proj=utm +zone=55 +south +ellps=aust_SA +nadgrids=AGD66.gsb +units=m +no_defs (I renamed the unzipped distortion file 'A66 National (13.09.01).gsb' file to 'AGD66.gsb' for convenience) But I can't make the parameters stick in the CRS of a vector file using the override facility. Any ideas?

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