AnsweredAssumed Answered

Subdivision - duplicates being created

Question asked by BTLeslie on Nov 28, 2014
Latest reply on Jan 5, 2015 by BTLeslie

Version = 2014.1

Input  = Shapefiles

 

My shapefiles represent generalised footprints of groups of buildings so my first step is to Subdivide my shapes into individual footprints using the subdivide tool.

 

I start with 666 objects in my layer (a small town) but after subdividing I have almost 400 000 - this is ridiculous and not a number my computer can reasonably deal with - from a visual check I estimate that my largest initial object is subdivided into no more than 50 objects (this should mean the absolute maximum number of objects I should end up with is 30 000).

 

Here's a smaller example to illustrate:

 

Input = 2 objects

Subdivide settings - see imagesubdiv settings.jpg

 

Result - 31 objects, however visual count suggests there should only be 20 - see image.footprint count.jpg

 

It appears that some footprints have been duplicates - see image duplicate.jpg

ETA -- I seem to get the same outcome in v2012.1

 

ETA_2 -- Attributes get completely screwed up too.  So in my first example (666 initial shapes --> ~400 000 objects), I look at one footprint and I find that there are 127 duplicates - and all of them have different attributes i.e.

Duplicate1:  Category = RES, Area = 3005

Duplicate2:  Category = RES, Area = 2676

Duplicate3:  Category = COM, Area = 17165

Duplicate4:  Category = IND, Area = 22046

etc.

Outcomes