Converting ArcMAP shapefile UTM coordinates from NAD27 to NAD83

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04-08-2010 12:40 PM
JasonSchilling
New Contributor
Hey everyone,
I have converted the coordinate system of several point shapefiles from NAD27 to NAD83 using the following function in ArcToolbox:

data management tools/projections and transformation/feature/project

When the project window opens the input coordinate system is automatically entered as :

"NAD_1927_UTM_Zone_10N."

I chose "NAD_1983_UTM_Zone_10N" as the output coordinate system

For the geographic transformation pull down option, I chose "NAD_1927_To_NAD_1983_NADCON"

This creates a new shapefile. However, the UTM coordinates for the new shapefile are identical to the old shapefile, even though their respective coordinate systems are different according to the layer properties tab.  Does anyone know how to correct this?  These coordinates are in Washington State, and I am assuming that their would be a difference in coordinates between the two systems.

Thanks in advance for any help you can offer with this.

Jason
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MelitaKennedy
Esri Notable Contributor
Hey everyone,
I have converted the coordinate system of several point shapefiles from NAD27 to NAD83 using the following function in ArcToolbox:

data management tools/projections and transformation/feature/project

When the project window opens the input coordinate system is automatically entered as :

"NAD_1927_UTM_Zone_10N."

I chose "NAD_1983_UTM_Zone_10N" as the output coordinate system

For the geographic transformation pull down option, I chose "NAD_1927_To_NAD_1983_NADCON"

This creates a new shapefile. However, the UTM coordinates for the new shapefile are identical to the old shapefile, even though their respective coordinate systems are different according to the layer properties tab.  Does anyone know how to correct this?  These coordinates are in Washington State, and I am assuming that their would be a difference in coordinates between the two systems.

Thanks in advance for any help you can offer with this.

Jason


Hi Jason,

How are you checking the coordinate values? Are you looking at the attribute table? Any coordinate values in the attribute table are not updated after a projection. You could use Calculate Geometry in ArcMap and update the values or add new fields and add the new, NAD83-based values.

If you're checking by hovering over points in ArcMap, try "clearing" the data frame's coordinate system, when you have both layers added. You should see offsets between corresponding features.

Melita
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JasonSchilling
New Contributor
Hi Jason,

How are you checking the coordinate values? Are you looking at the attribute table? Any coordinate values in the attribute table are not updated after a projection. You could use Calculate Geometry in ArcMap and update the values or add new fields and add the new, NAD83-based values.

If you're checking by hovering over points in ArcMap, try "clearing" the data frame's coordinate system, when you have both layers added. You should see offsets between corresponding features.

Melita



Thanks Melita. I was checking the coordinate values by looking at the attribute table. Your advice cleared everything up.

Jason
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