How to Compile vlfeat library on Octave

Question

I want to use vlfeat library on Octave but the vlfeat.org does not have instructions for installing it on Octave. Any help/pointers would be appreciated.

Answer 1

I needed to apply a patch to the octave makefile. Here is a complete script to make vlfeat run on a fresh install of Ubuntu 13.04:

# install required packages
sudo apt-get install octave octave-pkg-dev build-essential octave-image transfig

# get vlfeat
wget http://www.vlfeat.org/download/vlfeat-0.9.16.tar.gz
tar xzvf vlfeat-0.9.16.tar.gz

# apply patch
cd vlfeat-0.9.16
sed -i 's/mex $(OCTAVE_MEX_FLAGS)/mex $(OCTAVE_MEX_FLAGS) $(OCTAVE_MEX_LDFLAGS)/' make/octave.mak

# compile
MKOCTFILE=mkoctfile make

# run demo
mkdir -p doc/demo
cd toolbox
octave --persist --eval "vl_setup; vl_demo"

On my system the demo executes until it hits a point where the current architecture is need. It seems like octave is not recognized at this step and the demo stops. But nevertheless it is able to produce some plots which shows it is generally working. But I don't know to which extent since I have not done any further tests.

Update:

To run phow_caltech101 I first had to install liblinear since the provided SVM usese some matlab function not provided by octave:

cd 
wget "http://www.csie.ntu.edu.tw/~cjlin/cgi-bin/liblinear.cgi?+http://www.csie.ntu.edu.tw/~cjlin/liblinear+tar.gz" -O liblinear.tar.gz
tar xzvf liblinear.tar.gz
cd liblinear-1.93/matlab
sed -i 's/include\/octave/include\/octave-3.6.4\/octave/' Makefile
make octave

Than I had to patch some vlfeat files:

cd
cd vlfeat-0.9.16
patch -p0 << EOF
--- apps/phow_caltech101.m    2012-10-04 11:57:08.000000000 +0200
+++ apps/phow_caltech101.m    2013-06-07 12:37:29.413434382 +0200
@@ -56,7 +56,7 @@
 conf.numSpatialY = [2 4] ;
 conf.quantizer = 'kdtree' ;
 conf.svm.C = 10 ;
-conf.svm.solver = 'pegasos' ;
+conf.svm.solver = 'liblinear' ;
 conf.svm.biasMultiplier = 1 ;
 conf.phowOpts = {'Step', 3} ;
 conf.clobber = false ;
@@ -218,6 +218,8 @@
                           conf.svm.biasMultiplier, conf.svm.C), ...
                   'col') ;
       w = svm.w' ;
+      b = w(end,:);
+      w = w(1:(end-1),:);
   end
 
   model.b = conf.svm.biasMultiplier * b ;
@@ -259,7 +261,7 @@
 % -------------------------------------------------------------------------
 
 im = im2single(im) ;
-if size(im,1) > 480, im = imresize(im, [480 NaN]) ; end
+if size(im,1) > 480, im = imresize(im, [480 round(480*size(im,2)/size(im,1))]) ; end
 
 % -------------------------------------------------------------------------
 function hist = getImageDescriptor(model, im)
EOF


patch -p0 << EOF
--- toolbox/sift/vl_phow.m    2012-10-04 11:57:08.000000000 +0200
+++ toolbox/sift/vl_phow.m    2013-06-07 12:08:43.653416992 +0200
@@ -135,6 +135,8 @@
     sigma = opts.sizes(si) / opts.magnif ;
     ims = vl_imsmooth(im, sigma) ;
 
+    ims = im2single(ims);
+
     % extract dense SIFT features from all channels
     for k = 1:numChannels
       [f{k}, d{k}] = vl_dsift(...
EOF

Then I was able to successfully run it:

octave --eval "addpath('~/liblinear-1.93/matlab'); cd toolbox; vl_setup; cd ../apps; phow_caltech101" --persist