[Insight-users] drawing circle on itk image

[Martin Urschler]

hi

i'm not sure if this is the most straightforward way to do that, but it 
should work without large effort, however it takes some computation time 
if you have a large volume to fill with a 3D contour

1. create your circle using an itkEllipseObject spatial object
2. voxelize a volume containing a filled circle using the IsInside 
method of the spatial object
3. extract the border of the voxelized filled circle using a 
morphological operation (e.g. subtraction of an eroded version of the 
filled circle)

i'm not aware of a more direct method to specify an initial deformable 
contour (perhaps there are some routines in the level set framework?), 
but i guess it would be very convenient to write an image source object 
for that which simply iterates over an image and for each pixel checks 
if it lies on the specified circle

hth
Martin

sami bourouis wrote:
> Dear all,
> 
> I would like to create a circle, given a specified center and radius.
> I would like to intialize this circle like a "deformable contour" and 
> deforme it under the action of enrgy function. the objective ok my work, 
> firsly,  is to re-implement the classic snakes (active contour) (Kass et 
> al 1988).
> Any suggestions? essentially for initialization of a circle,
> thanks !