Dear friends,
George was right when he said Krassovsky is an ellipsoid or spheroid
according to the MI references, but I know that was not what BDT expected.
Giving you a hint from MapInfo User's Reference (guessed both of you have
not read it), I think it can help BDT solve his problem:
1. BDT has to define a new Datum
- BDT used 10 for Mercator, that's correct !
- BDT used 2 for Krassovsky, that's not correct because it's the Afgooye
datum for Somali. BDT has to use 9999 or 999 to make a custom datum.
- To define a new datum, BDT must follow the format:
9999, Ellipsoid Number, dX, dY, dZ, Ex, Ey, Ez, m, Prime
Meridian
- So I guess BDT may use the following parameters to make his datum:
+ Ellipsoid Number: 3
+ dX: 24
+ dY: -123
+ dZ: -94
+ Ex: -0.02
+ Ey: 0.25
+ Ez: 0.13
+ m: 1.1
+ Prime Meridian: 0
2. Once you've got a custom datum, BDT can make a new line in MAPINFOW.PRJ
as follows:
"Mercator Projection for Vietnam - Krassovsky (Lat 16/Long 16)",
10, 9999, 3, 24, -123, -94, -0.02, 0.25, 0.13, 1.1, 0, 7, 105, 16, 1,
500000, 0
--> Where 16 means Origine Latitude is 16; 105 stands for Zone 48; 500000
and 0 make his projection NorthEast.
3. For most cases in Vietnam, Universal Transversed Mercator projection is
used instead of Mercator. With this projection, Origine Latitude is 0.
Indian datum (Everest Ellipsoid) is used for UTM.
You can make use of this discussion for reference when creating new
projection string in MapInfo. For more information and further discussion,
please contact:
Do Minh Phuong
GIS Specialist and Database Manager
Remote Sensing and Informatics Center
National Institute for Agricultural Planning and Projection
61 Hang Chuoi, Hanoi, Vietnam
Fax: 844-821-4163
Email: [EMAIL PROTECTED]
[EMAIL PROTECTED]
Good luck.
P.M. Do
At 03:32 PM 10/1/99 +0700, you wrote:
>Hello everyone,
>I have problem when create new MI projection
> Projection Mercator
> Datum Krassovsky
> Unit m
> Origin longitude 105 degree E
> Origin latitude 16 degree N
> Latitude true scale 16 degree N
>
>How I can create new line in MI projection file?
>
>I try with this line with Mercator:
>
>"New Prj", 10,2,7,105
>
>But it not correct? How to do it right?
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