[Proj] GDM2000 for Malaysia

[Bjørn Krangnes]

I have now been looking at this again and my findings are that the program
cs2cs is working correct while using gdal in a c# enviroment gives
problems. Without the use3 of no_uoff and rot_conv both programs gives the
 same result:
** cs2cs
cs2cs +proj=longlat +ellps=GRS80 +no_defs +to +proj=omerc +
lat_0=4 +lonc=102.25 +alpha=323.0257964666666 +k=0.99984 +x_0=804671
+y_0=0 +ellps=GRS80 +units=m +no_defs
103.64025987222223 1.827764875
959373.97       -240050.80 0.000

**gdal
inn = inpGDM2000.ImportFromProj4("+proj=longlat +ellps=GRS80 +no_defs  <>");
out = outRSO.ImportFromProj4("+proj=omerc +lat_0=4 +lonc=102.25
+alpha=323.0257964666666 +k=0.99984 +x_0=804671 +y_0=0 +ellps=GRS80
+units=m +no_defs <>")
959373.969 -240050.800

with no_uoff and rot_conv option
** cs2cs
cs2cs +proj=longlat +ellps=GRS80 +no_defs +to +proj=omerc +
lat_0=4 +lonc=102.25 +alpha=323.0257964666666 +k=0.99984 +x_0=804671
+y_0=0 +ell ps=GRS80 +units=m +no_uoff +rot_conv +no_defs
103.64025987222223 1.827764875
627096.13       202122.06 0.000

**gdal
inn = inpGDM2000.ImportFromProj4("+proj=longlat +ellps=GRS80 +no_defs  <>");
out = outRSO.ImportFromProj4("+proj=omerc +lat_0=4 +lonc=102.25
+alpha=323.0257964666666 +k=0.99984 +x_0=804671 +y_0=0 +ellps=GRS80
+units=m +no_uoff +rot_conv +no_defs <>")
959373.969 -240050.800

It looks that the +no_uoff +rot_conv is not used in the gdal enviroment

bjørn

> Bjørn Krangnes wrote:
>> I am using GDAL 1.4.0 and C#.
>> I am getting other coordinate transformations to work.
>> The TransformPoint function returns no status (void function).
>> You are saying that my proj strings are ok.
>>
>> How should I proceed to sort out my problem ...
>
> Bjørn,
>
> First, it does not appear the problem is related to GDAL or C# since
> people get the same results with cs2cs which is a much more direct
> connection to the proj libraries.  So I think you can focus here on
> why you get the wrong results from cs2cs.
>
> You have posted the issue here, and clearly at least a couple people
> have looked at it quickly with no obvious solution.
>
> I can see two further steps:
>
>   o You can dig up papers on the coordinate system in question and try to
>     understand the parameters better and see if you can come up with a
>     better PROJ.4 string to represent the parameters.  Possibly this would
>     invole comparing how this projections works in other systems.
>
>   o You could attempt to commercially engage someone to help you with the
>     problem.  Possibly you could interest Gerald in the issue with some
>     inducement.  I might be willing to take a crack at it on a
>     no-risk-if-I-fail basis.
>
> Best regards,
> --
> ---------------------------------------+--------------------------------------
> I set the clouds in motion - turn up   | Frank Warmerdam,
> warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
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>
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Bjørn Krangnes
Devonor AS
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E-mail: bkr at devonor.com
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