[Insight-developers] Re: BlobSpatialObject

[Stephen R. Aylward]

BlobSpatialObjects are defined by a list of points in index space (the 
points occupy (e.g., measure) a volume of physical space and the size of 
that volume is determined by a "spacing" transform - like points/indexes 
in an image).

To test isinside for a worldpoint, it does a worldToIndex transform, and 
then sees if the resulting indexpoint is within 0.5 index units (using 
independent city-block distance measures) of any point/index in the list 
that defines the blob spatial object.

BUT, your question pointed out a bug in the IsInside function - I just 
checked in a fix.   It was actually doing a very funky (aka wrong) 
distance from index test.   THANKS!

Does this answer your question?  Seem valid?

Thanks,
Stephen

Will Schroeder wrote:

> Hey Stephen-
> 
> Is the BlobSpatialObject assumed to be a convex set of points? What does 
> it mean to be inside a blob (defined by points)?
> 
> Will
> 
> 
> 

-- 
===========================================================
Dr. Stephen R. Aylward
Associate Professor of Radiology
Adjunct Associate Professor of Computer Science and Surgery
http://caddlab . rad . unc . edu
aylward at unc . edu
(919) 966-9695