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Indonesia data projection   Martie Clemons Mar 08, 2004
Re: Indonesia data projection   Melita Kennedy Mar 08, 2004
Re: Indonesia data projection   Martie Clemons Mar 08, 2004
Re: Indonesia data projection   Martie Clemons Mar 08, 2004
Re: Indonesia data projection   Melita Kennedy Mar 08, 2004
Re: Indonesia data projection   Martie Clemons Mar 09, 2004
Re: Indonesia data projection   Melita Kennedy Mar 09, 2004
Re: Indonesia data projection   Martie Clemons Mar 09, 2004
Re: Indonesia data projection   Melita Kennedy Mar 09, 2004
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Subject Indonesia data projection 
Author Martie Clemons 
Date Mar 08, 2004 
Message I inherited some data for south Borneo and need to know which projection and coordinate system they're in. There were no metadata available. A JPG of a map someone else created using these data shows coordinates and "UTM" along the grid edges. However, when I tried assigning UTM Zone 49S to the data in ArcToolBox, it didn't project on the fly correctly in ArcMap, i.e. it didn't come into the other data I have known projections for. Is there any way to determine which projection and coordinate system these data are in? A sample coordinate is: x = 9,660,000 y = 612,000 
   
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Subject Re: Indonesia data projection 
Author Melita Kennedy 
Date Mar 08, 2004 
Message EPSG (http://www.epsg.org) doesn't have anything that matches. The closest is a NEIEZ zone that uses 3900000 for x, 900000 for y, with the center at 110E, 0N.

If you just switch the xy values, it's classically a UTM South zone! Could someone had georeferenced the data incorrectly?

Melita 
  Melita Kennedy
ESRI Product Specialist 
   
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Subject Re: Indonesia data projection 
Author Martie Clemons 
Date Mar 08, 2004 
Message Thanks for your reply. I have the coordinates switched around in my head and so I wrote them down incorrectly. So, I presume that they are UTM coordinates ... but I still don't know how to define a projection for them. In ArcToolBox, do I choose Transverse Mercator projection or should I choose Lambert Conformal or UTM? If I choose either of the first two, I have no idea how to fill in all the projection parameters. If I choose UTM projection, Zone 49, meters (I assume), which datum do I choose?

I don't know how to find this information and would greatly appreciate any help. 
   
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Subject Re: Indonesia data projection 
Author Martie Clemons 
Date Mar 08, 2004 
Message I just defined the data's projection as UTM, zone 49, meters and WGS 1984 datum. It gave me no choice as to north or south - do I need to input an x or y shift and if so, how?

When I open a blank ArcMap project and point to the data, the data frame projection shows it as Zone 49N (not south). Then when I pull in the other data I have that's in geographic, they're far apart but fairly well aligned longitudinally, as though it's a North/South problem.

Any suggestions? 
   
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Subject Re: Indonesia data projection 
Author Melita Kennedy 
Date Mar 08, 2004 
Message Oh, it's a grid? You may need to edit the prj.adf file directly for the grid. In the prj.adf file, delete the 'zone 49' line. After the parameters line, add:

111 0 0.0
-10 0 0.0

This will trigger ArcInfo to realize that it's a south zone. Or you can use Transverse Mercator so the information would look like this:

projection transverse
units meters
datum wgs84
parameters
0.9996
111 0 0.0
0 0 0.0
500000.0
10000000.0

Melita 
  Melita Kennedy
ESRI Product Specialist 
   
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Subject Re: Indonesia data projection 
Author Martie Clemons 
Date Mar 09, 2004 
Message Thanks for the info about grids, Melita - that's good to know and I'll keep it for future use. However, my data aren't grids. The reference I made to a grid on the JPG was about the grid ticks. I went ahead and set the projection, though, as Transverse Mercator with the parameters you wrote and it comes in with other projected data correctly. However, I'm still wondering if I should really set the projection to UTM Zone 49 and do some sort of x,y shift to make it come in south rather than north. 
   
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Subject Re: Indonesia data projection 
Author Melita Kennedy 
Date Mar 09, 2004 
Message We often have south UTM zones. If you're using a WGS84-based UTM zone, we definitely have both the north and south zones. Otherwise, you can always use a corresponding north zone and modify it. The PROJCS name should change, but besides that, only the false northing value changes to 10000000.0.

Melita 
  Melita Kennedy
ESRI Product Specialist 
   
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Subject Re: Indonesia data projection 
Author Martie Clemons 
Date Mar 09, 2004 
Message Thank you so much! That 10000000.0 false northing changed it to south and that was exactly what I needed. I really appreciate all of your speedy and most helpful replies. The only thing that I'm not certain about is the projection - can I assume that it's WGS 1984? I have no way of knowing, or do I?

Thanks again! 
   
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Subject Re: Indonesia data projection 
Author Melita Kennedy 
Date Mar 09, 2004 
Message Not without a pretty accurate test point, and its coordinates in a known system. That still might only tell you that it's not based on the known system.

Melita 
  Melita Kennedy
ESRI Product Specialist