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| Perlis cadaster plan sits spot on with Google Hybrid |
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| Perlis cadaster map projection parameters |
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| Perlis topographic map |
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| Perlis topographic map projection parameters |
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| Note how far they are apart |
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| Enter the Export to new projection module |
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| Configure the Export to new projection module |
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| Sadly no effect |
Export to new projection module fails but why?
This test uses the Vector/Data Management Tool called "Export to new projection" and created a new topography layer by using the topographical plan then borrowing the map projection from the cadaster plan which already sits perfectly on site at the Google Hybrid yet did not turn out well. I am trying to diagnose why did it fail? Presently, the only answer I can come up with but I may be wrong is that the topographic map (here again, I am assuming) had its map projection roots base on the Geographic Coordinate System/Kertau (RSO) whereas the map project for the Cadaster plan was base on a different projection system category that is User Defined Coordinate System and they are not birds of a feather, unless of course, it can be done but that I simply do not know how-to. Rats! Asking around from my more experienced staff, I come to realize this RSO-Cassini thing is much more complex than I assume it would be which we hope migration to the GDM2000 map projection will resolve much of the outstanding issues. Funny thing is that when I referred to ArcGIS way, it appears their Data Management Tool method used is similar that is called a 'Project' module. This only makes it more intriguing. I was made to understand that the RSO-Cassini reprojection is a sequential step that has a hop, skip and jump step from RSO to WGS84 to Cassini and what I did was hop and jump which is a no-no. Still I think the user is bounded by the rules or parameters behind the scene set by what the software impose hence it may work with one software but may not with another although the procedure are the same but I am still wondering why working with the custom CRS inputting your preferred parameters based on one that works does not get you the result you seek unless of course the custom CRS setting behind the scene also needs "remapping" like what I did for my car's ECU.
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| Firstly, cadaster plan with user defined coordinate system |
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| Secondly saved as on RSO (Kertau) projection |
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| Thirdly, RSO-ed layer saved as WGS84 projection |
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| Lastly, WGS84-ed layer saved as cassini Perlis proejection |
Assalam En Abbas...
ReplyDeletesaya mmg dah lama try to convert rso > wgs, wgs > rso guna qgis tapi masih tak berjaya. Saya pernah utarakan masalah ni dahulu di post tuan .. http://qgismalaysia.blogspot.com/2011/09/huh-susah-ke-nak-convert-projection.html
Wslm. Saya ada merujuk bagaimana ArcGIS melaksanakannya dan dapati ianya menggunakan Data Management Tools/Projection and Transformations/Features/Project yakni menyerah pada modul Project untuk transformasikan projection MRSO kepada WGS1984. Kaedah ini saya lihat adalah sama saja dengan QGIS Data Management Tools/Export to new projection cuma saya tak faham mengapa QGIS tak menghasilkan output sama. kalau nak tahu lebih lanjut, kita perlu mengkaji rules yang digunakan dalam modul QGIS tapi saya rasa itu kerja programmer bukan end-user am seperti saya.
DeleteThis guy nmpaknya dah byk explore on qgis rso projection.. maybe dia ada solution. En Abbas kenal ke en hilmy ni??
Deletehttp://osgeo-org.1560.x6.nabble.com/RSO-gamma-and-Hotine-Oblique-Mercator-Variant-A-td3841370.html
TK. Sedang buat contact. Namanya Hilmy Hashim
ReplyDeleteAssalamualaikum, En. Abbas.
ReplyDeleteSaya juga mengalami masalah ini. Penerangannya dan kaedah penyelesaian yang saya gunakan boleh dirujuk di URL berikut.
http://www.myqgis.blogspot.com/2012/10/mengguna-data-mrso-arcgis.html
Contoh yang diberi oleh saudara berjaya tapi menggunakan perisian bukan QGIS maka pengguna hardcore QGIS tak puas hati. Kini, saya sedar pangkalan data QGIS berkaitan QGIS berbeza dan sehingga dikemaskini oleh pihak QGIS. Mengikut Q&A dari blog saudara, En.Howard berkata "Ultimately, we have to depend on the GDAL corrections to be built into the CRS database that QGIS uses." Tidak bermakna tak boleh buat sebab QGIS pernah kata dalam User Manualnya kalau tak puashati dengan setting mereka, sila masukkan parameters tersendiri dalam Custom CRS. Howard juga berkata "...Otherwise, we have to make our own custom CRS file."
Delete