Posted by
Gabriel Landini on
Oct 12, 2009; 11:07pm
URL: http://imagej.273.s1.nabble.com/Stereo-topography-tp3690806p3690809.html
On Monday 12 October 2009 22:56:31 Anovitz, Lawrence {Larry} M. wrote:
> 1. most importantly, do you have any idea how do I get the elevation map
I read a paper long ago on this. I think it is this one, but I cannot access
it from here:
http://www.mrs.org/s_mrs/bin.asp?CID=7589&DID=186904&DOC=FILE.PDF> 2. what's the best way to try the flooding ?
You do a 'cut' at certain height. So everything higher than a value is set to
the foreground value (island) and evertyhing lower is set to the background
(water).
Then, extract the edges and compute the box dimension.
One could do a heightmap with pixel values and then threshold it.
Actually this is an intersection of your object with a plane.
One might try different orientations of the cutting plane.
> 3. are you sure the 3d dimension is D(2)+1 ?
I seem to remember that there is a theorem on this in Tamas Vicsek's book
Fractal Growth Phenomena. So one reduces 1 the dimension by intersecting the
3d structure with a 2d plane.
I just tried to find that theorem and found this instead:
Chemical Physics Letters. Volume 433, Issues 1-3, 29 December 2006, Pages
248-252.
which seems to argue that the relation does not always hold for some objects.
(I have not read the whole paper, just the abstract).
> Could it be (3/2)D(2), or even not necessarily directly related ?
Where is 3/2 coming from? if the 2D dimension of the zero set (the section) is
1, (e.g. a plane intersected by another plane) in 3d this would mean D(3)=1.5
instead of 2.
> 4. I agree wrt the limitations of the stereo pairs. I may be able to
> improve this by making and combining several stereo pairs at different
> tilts.
Depends on the object. If too irregular I think you will not get all the
detail, but perhaps your specimens are not that complex.
Cheers
G.