[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: SIFT image descriptor patch
From: |
Etienne Grossmann |
Subject: |
Re: SIFT image descriptor patch |
Date: |
Tue, 14 Feb 2006 05:56:37 -0500 |
User-agent: |
Mutt/1.4.2.1i |
Are the rsults ugly?
On Mon, Feb 13, 2006 at 09:36:33PM +0100, Søren Hauberg wrote:
# Etienne,
# Thanks for doing this, it's nice to have SIFT in Octave.
# I get the following error on some images:
#
# error: linspace: npoints is 1, but x1 != x2
# error: evaluating argument list element number 1
# error: evaluating argument list element number 2
# error: evaluating assignment expression near line 28, column 6
# error: evaluating for command near line 22, column 1
# error: called from `imglines' in file `/home/sh/Dokumenter/Robot
# projekt/Octave siftDemo/imglines.m'
# error: evaluating assignment expression near line 42, column 9
# error: evaluating if command near line 14, column 1
# error: called from `showkeys' in file `/home/sh/Dokumenter/Robot
# projekt/Octave siftDemo/showkeys.m'
#
# I fixed this by a very dirty hack. That is,
# if (len <= 1) len = 2; endif
# in imglines.m
#
# Thanks,
# Søren
#
# tir, 27 12 2005 kl. 11:32 -0500, skrev Etienne Grossmann:
# > Hi All,
# >
# > this patch could be of interest to octave users who do image
# > processing. You can apply it to the matlab code in siftDemoV4 [1] to
# > allow octave to extract SIFT image features [2] with David Lowe's
# > package.
# >
# > The SIFT image detector identifies interest points, somewhat like a
# > corner detector does, and gives them a local descriptor. The
# > descriptor can then be used for matching purposes (another way to
# > perform matching could be correlation of a small window around the
# > feature). Wrt to corners + local window correlation, SIFT features are
# > more robust to changes in illumination and viewpoint [3] and they are
# > increasingly used in computer vision.
# >
# > The siftDemo has functions to find sift features and to perform
# > matching. I've tested the patch under octave+linux, matlab+linux (it
# > works) and octave+win (it fails, probs w/ imagemagick + double).
# >
# > Hth,
# >
# > Etienne
# >
# >
# >
# > [1] http://www.cs.ubc.ca/spider/lowe/keypoints/siftDemoV4.zip
# >
# > Synopsis:
# >
# > unzip siftDemoV4.zip;
# > cd siftDemoV4;
# > patch -p1 < mySift.patch
# >
# > In octave, make sure sift.m is in your path, then
# >
# > >> [image, descriptors, locs] =
sift("/home/etienne/prog/various/siftDemoV4/book.pgm");
# > >> showkeys(image, locs)
# >
# > See also 'help match'
# >
# > [2] http://www.cs.ubc.ca/~lowe/keypoints/
# >
# > David G. Lowe, Ãbject recognition from local scale-invariant
# > features," International Conference on Computer Vision, Corfu,
# > Greece (September 1999), pp. 1150-1157.
# >
# > [3] A performance evaluation of local descriptors Krystian
# > Mikolajczyk, Cordelia Schmid International Conference on Computer
# > Vision & Pattern Recognition - June 2003
# >
# > http://lear.inrialpes.fr/pubs/2003/MS03/mikolajczyk_cvpr2003.pdf
# >
# >
--
Etienne Grossmann ------ http://www.cs.uky.edu/~etienne
-------------------------------------------------------------
Octave is freely available under the terms of the GNU GPL.
Octave's home on the web: http://www.octave.org
How to fund new projects: http://www.octave.org/funding.html
Subscription information: http://www.octave.org/archive.html
-------------------------------------------------------------