I have been spending weeks to write a conjugate gradient program to do multi-dimensional minimization. But the results didn’t seem to be right. I’m also reluctant to use Matlab optimization toolbox, although it is very powerful. So I searched again and again, and re-found GSL. GSL is numerical library for c/c++ programmers, of course it includes minimization functions. Also, opt++ (http://csmr.ca.sandia.gov/opt++/) seems to be not bad.

I use to write my own opencv program to stack a set of images for viewing, e.g. rectification results of multiple images. But today I want to give ImageMagick a try. I searched on-line, and find many extremely useful features of ImageMagick. To stack a set of images, I could use ‘convert’ command with option ‘+/-append’. I could also ‘montage’. Some examples go follows:

  montage -label Balloon   balloon.gif  \
       -label Medical   medical.gif  \
       \( present.gif  -set label Present  \) \
       \( shading.gif  -set label Shading  \) \
       -tile x1  -frame 5  -geometry '60x60+2+2>' \
       -title 'My Images'     titled.jpg

or

 montage -font Times-New-Roman -pointsize 24 \
       -label (a) F28_IMG_0001.ppm \
       -label (b) F28_IMG_0002.ppm \
       -label (c) F28_x.ppm \
       -tile x1 -geometry +10+10 titled.jpg 

These commands are really cool. I don’t need Illustrator anymore for preparing my paper figures. http://www.imagemagick.org/Usage/montage/

I always tried to find good materials to build the camera array with low cost. However, the only think I can only find is slotted metal at Low’es and Homedepot. These metals are very heavy, and are not easy to align the camera array either. Slide bar in the market (http://www.stereoscopy.com/jasper/slide-bars.html) is way too expensive.

Today I found T slot aluminum. http://www.faztek.net/downloads.html. This is very good to build staffs. With linear bearing, I can build a slider on the rail very quickly, and I could also add a fastener to the side of the roller to fix the position of the camera.