shrug-l: Lat-Long

Elebash, Alan Alan.Elebash at dep.state.fl.us
Thu Dec 22 12:06:25 EST 2005


This is from ArcGIS 9.1 help:
 
About saving data to a new projection 
When you export data from ArcMap, you can choose to create a new feature
class <javascript:glossary_feature_class22168.Click()>  using a different
coordinate system than that of the source data, use the coordinate system
<javascript:glossary_coordinate_system22168.Click()>  of the data frame
<javascript:glossary_data_frame22168.Click()> , or use the coordinate system
of the feature dataset <javascript:glossary_feature_dataset22168.Click()>  to
which you are exporting the data. 
In ArcCatalog, when you export data to a feature dataset in a geodatabase, it
will use the coordinate system of the feature dataset. If you export data as
a standalone feature class or to a file-based data source, it will have the
same coordinate system as the source data. 
The ArcToolbox Project tool <javascript:project_esri221680.Click()>  allows
you to make a copy of your data and change its coordinate system. This tool
changes the coordinate system of the data and transforms the shapes in the
data to use the new coordinate system. You can use the Project tool as part
of a model or as you need it while working in ArcMap or ArcCatalog. 
If your data's geographic coordinate system
<javascript:glossary_geographic_coordinate_system22168.Click()>  uses a
different datum <javascript:glossary_datum22168.Click()>  than that of the
new feature class, you will likely write spatially inaccurate data. Instead
of directly writing to the new feature class, make a copy of the original
feature class and use the Project tool to reproject that feature class to the
coordinate system that you ultimately want to use. As part of using the
Project tool, you will be able to specify a datum transformation. Once you
have projected the copy, you can copy it into the new workspace and delete
the first copy. This applies to any place in ArcMap or a geoprocessing tool
that is able to write new data. 
 
 
Hope this helps.
Alan Elebash 
GIS Analyst 
Office of Park Planning 
Division of Recreation and Parks 
850  245-3051 
Florida State Parks - the "Real Florida" 
www.floridastateparks.org 
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