Buffer length in feet for feature class in WGS 84

750
4
11-26-2013 05:00 AM
AndrewL
Occasional Contributor II
Hi I would like to buffer a polyline feature class in Coordinate System of WGS 84 using 300 feet.

I am getting the error ExecuteError: ERROR 000599: Falls outside of output geometry domains.

I tried to calculate 300ft as decimal degress using a formula found online but the measurement does not come out correctly when measuring in ArcMap. Calculated to 0.00082296 dd, but the measure distance in ArcMap was about 265ft. I did not receive an error however.

The polylines cover most of the 48 states. Would I need to reproject this to a new feature class and then do the calculation? Thank you.

Andrew
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4 Replies
SachinKanaujia
Occasional Contributor III
Yes you should project it to an appropriate/applicable PCS for accurate results. You can choose a NAD27 or NAD83 based State plane or UTM projection applicable for the AOI you are working on !!!
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AndrewL
Occasional Contributor II
Thank you! If my AOI is ever changing (since it will depend on tornado tracks that can vary all over the 48 states) should I just choose a PCS that is centered on the AOI? Such as UTM 15N? Most likely tornadoes will occur between the Great Plains and the southeastern USA.

I am incorporating this into a python script. Thank you.

Andrew
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SachinKanaujia
Occasional Contributor III
Depends. If you want to cover the whole of US 48 states then you may try using US National Atlas Equal Area (EPSG:2163).
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markdenil
Regular Contributor II
Defiantly choose a projection that covers your whole area, and serves your needs.
UTM only usefully covers 6° longitude: outside that zone, the distortions become large
both quickly somewhat un-intuitively.

A stereographic conic like Lamberts Conformal Conic,
with appropriate central meridian and standard parallels, would be a good choice
for tracking tornados, I should think.
(there is a standard one for the continental US built into ArcGIS)
Area is likely not critical, so an equal area conic is not recommended.

Getting exactly measured buffers is tricky, since even in a measured coordinate system
actual measurement units are creatures of the system.
Except right at the place where the scale factor equals 1, the length will be larger or smaller than the nominal distance.
A secant projection (like the Lamberts Conformal Conic) spreads the error across the AOI,
minimizing its effect.
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