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| GeoCommunity Mailing List |
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| Mailing List Archives |
| Subject: | Re: [gislist] mrsid coordinate system information |
| Date: |
09/30/2005 06:15:01 PM |
| From: |
Bryan Keith |
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Bill,
You are correct. It's simple to calculate the zone given the
information ArcMap returned which is why I thought it was interesting
that the zone wasn't reported.
Since my first e-mail I have examined another sid file which ArcMap
reports is:
Unknown
Note: one or more layers is missing spatial
reference information. Data from these layers
cannot be projected.
and GlobalMapper reports is:
UTM, Zone 13, NAD27, meters
Where is GlobalMapper getting this information? Currently the only
reliable way we've found to discover the coordinate system of a sid file
is to open the file in GlobalMapper. That's not a practical solution
for lots of files or for automated processing.
Bryan
Bill Thoen wrote:
>You can easily calculate the zone. Each zone is 6 degrees, starting with zone 1
>between 174 and 180W. Since the CM of -105 is 75 degrees from -180, then
>75/6 = 12.5, so you round up and the UTM zone is 13.
>
>HTH,
>- Bill Thoen
>
>On Fri, Sep 30, 2005 at 04:32:01PM -0600, Bryan Keith wrote:
>
>
>>Hi folks,
>>
>>Anyone know how to determine the projection of a sid file?
>>
>>LizardTech's tool mrsidinfo doesn't tell me. That surprised me. It
>>would be the best solution.
>>
>>ArcMap 9 gives me this information:
>>
>>UTM
>>Projection: Transverse_Mercator
>>False_Easting: 500000.000000
>>False_Northing: 0.000000
>>Central_Meridian: -105.000000
>>Scale_Factor: 0.999600
>>Latitude_Of_Origin: 0.000000
>>
>>GCS_NAD 83 (86)
>>
>>I find it interesting that it doesn't say what zone the image is in.
>>
>>A colleague reported that GlobalMapper says:
>>
>>UTM, NAD83, Zone 13, Meters
>>
>>So is this information stored in the header in the sid file? Is there a
>>tool to read that information directly? Thanks.
>>
>>Bryan
>>
>>Bryan Keith
>>GIS Specialist
>>Geomega, Inc.
>>Boulder, CO, USA
>>_______________________________________________
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>>http://lists.geocomm.com/mailman/listinfo/gislist
>>
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>
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