Identifying long, narrow polygons with FME

Hi,

 

 

I use the CircularityCalculator for these cases, it works well within the limitations of the feature's shape.

 

Hope this helps,

 

Itay

 

 

Also if these fields are actually donuts that you can use the DonutHoleExtractor

Hello,

 

 

an idea could be:

 

1. Use the BoundsExtractor to get for instance ymin and ymax per feature.

 

2. Use ExpressionEvaluator to get an _result attribute that calculates the

 

    difference between ymax and ymin.

 

3. Use AttributeRangeFilter to filter out all the features that have a difference of

 

    50 for instance for the _result Attribute.

 

 

 

-> in my small test scenario a was able to filter out long narrow features   

In FME 2012 and 2013, the BoundingBoxReplacer has the option for an Oriented Bounding Box. It will also give you the length of the short and long side of the bounding box. The ratio between short and long length would be a good indicator for narrowness.

Hi,   This is only an idea: When R is calculated by the following expression, I think that R of a linear thing such as irrigation canal will be very small. R = A / P; A is area and P is perimeter length of a shape. Whether the shape is a linear thing or not, can't we decide that according to R?