topic Re: Buffer raises error on any unit except decimal degree in Geoprocessing Questions

Buffer raises error on any unit except decimal degree

SimonGieser — Fri, 23 Aug 2013 09:45:21 GMT

Hello dear kind GIS Users,

i recently have trouble with the Buffer UPDATE: EVERYtool, when I want to buffer/erase/anything based on Units a Shape File Feature Class by 1000 Meters the Buffer Tool raises the error 999999. It is raised with any Unit Setting except Decimal Degrees.
Its the same when i try to do it via the python console. I think it has something to do with the values beeing processed as Strings, since i think there was some kind of string error raised, but now

import arcpy
arcpy.analysis.Buffer("landuse","landuse1000","1000 Meters")

does raise the error 999999

if i type it with no "" as a number

import arcpy
arcpy.analysis.Buffer("landuse","landuse1000",1)

The Buffer is processed but obviously with a way to huge radius.
Same goes with the Toolbox, nothing works except Decimal Degrees.

As I found out recently it the same with any Tool based on Units...

I don't know whats going on, I mean I get the hint with the string vs. integer, but I can't imagine that the buffer script is somehow corrupted. I would gladly appreciate if anyone can give me a suggestion what to do or a hint where the error is produced 🙂

Thanks in advance

Re: Buffer raises error on any unit except decimal degree

AmyKlug — Fri, 23 Aug 2013 19:57:43 GMT

It says the license level is "limited" for basic and standard.....I have no idea what that means. If you haven't already try and use ArcInfo. Just a thought

I'm also assuming in your code you defined your workspace ect.

EDIT: your license level should let you pick the units. Is the code you posted your entire code?

Re: Buffer raises error on any unit except decimal degree

RichardFairhurst — Fri, 23 Aug 2013 21:10:19 GMT

I am assuming your data is based on just a Geographic Coordinate System and only uses decimal degrees for its coordinate values. If so, I believe you can only use angular units to work with that data. You would need to use the Project tool to convert it to a Projected Coordinate System that uses linear units such as meters and that is designed to project area correctly. Once you have chosen a good projection use the Project tool to transform your data into a new feature class you can buffer with linear units such as meters.

Melita Kennedy is the resident ESRI projection expert on the forum. Here is some advice she has given others on the subject of choosing an equal areas projection:

"You'll want to use an equal-area projection. You'll find some for the US under projected coordinate systems, continental, north america like "USA Contiguous Albers Equal Area Conic USGS". You could modify it and change the central meridian and standard parallels into your area of interest, but I'm not sure the census data is accurate enough to warrant that. When we've done testing of various equal area projections, the density of the data (how many vertices) had a greater effect that which equal area projection was used."

Re: Buffer raises error on any unit except decimal degree

AmyKlug — Fri, 23 Aug 2013 21:56:33 GMT

I am assuming your data is based on just a Geographic Coordinate System and only uses decimal degrees for its coordinate values. If so, I believe you can only use angular units to work with that data. You would need to use the Project tool to convert it to a Projected Coordinate System that uses linear units such as meters and that is designed to project area correctly. Once you have chosen a good projection use the Project tool to transform your data into a new feature class you can buffer with linear units such as meters.

Melita Kennedy is the resident ESRI projection expert on the forum. Here is some advice she has given others on the subject of choosing an equal areas projection:

"You'll want to use an equal-area projection. You'll find some for the US under projected coordinate systems, continental, north america like "USA Contiguous Albers Equal Area Conic USGS". You could modify it and change the central meridian and standard parallels into your area of interest, but I'm not sure the census data is accurate enough to warrant that. When we've done testing of various equal area projections, the density of the data (how many vertices) had a greater effect that which equal area projection was used."

I think he is using the tool this way

�?�If buffering a projected feature class that has features covering a large region, or you are using a very large buffer distance, distortions in the projection can cause inaccurate buffers to be produced. You can completely avoid distortion when buffering by using a feature class that has a geographic coordinate system and specifying a Buffer Distance in linear units (meters, feet, and so forth, as opposed to angular units such as degrees). When this combination of inputs is used, the tool will generate true geodesic buffers that accurately represent distances on Earth's surface. Geodesic buffers may appear unusual on a flat map, but when displayed on a globe these buffers will look correct (you can use the ArcGlobe or ArcGIS Explorer applications to view geographic data on a three-dimensional globe).