Category Archives: howto

Processing + NyARToolkit + multiple marker tracking

Posted on June 5, 2010 | 98 Comments

For various reasons, I need to do multiple marker tracking in processing with NyARToolkit.  However, with the default NyAR4psg layer between these two, multiple marker tracking is downright hard, and when you get it working, it’s not quite what you expect. After a few days of Java hacking, during which I was very pleasantly surprised with eclipse, I am now pleased to present to you my modifications to the NyAR4psg that makes multiple marker tracking easy! See here:

Standard hiro and kanji markers tracked simultaneously with augmented reality sphere and cube. In the background some artwork by my daughter!

I’ve called it NyARMultiBoard, and you can use it instead of the default NyARBoard if you want to track multiple markers.

Download a ZIP file containing everything (source code, jar files) from this directory.  If you unpack this into your processing sketchbook/libraries directory, it should work out of the box.  It’s a drop-in replacement for NyAR4psg, so you don’t need to have that installed as well. There is an example to get you started in NyAR2/example/NyARMultiTest.  Note: This uses the GSVideo capturing stack as I explain here, you should easily be able to change it back to processing defaults (just change GSCapture to Capture).

Please let me know in the comments if this works (or doesn’t) for you!

I made this screencast to demonstrate the multiple marker tracking, assisted by TNR:

YouTube Preview Image

I also made this really bad screencast (old webcam + night time lighting + transcoding):

YouTube Preview Image

If you’re really into the details

I’ve just added two new classes NyARMultiBoard and NyARMultiBoardMarker to the default NyAR4psg distribution. Very importantly, NyARToolkit itself needs to be patched with one extra method in NyARDetectMarker, see the NyARMultiBoard comments.

Update on 20110304

I’ve fixed the problematic frame bug in gsvideo that many of you have been running into. See this post.

Update on 20110305

I’ve updated NyAR2 so it works with the P3D renderer as well, which is often faster for blitting the webcam image onto the display. The updated zip file is named NyAR2-20110305.zip, and it can be downloaded from the usual directory. My changes are based on NyAR4psg 0.3.0 and NyARToolkit 2.5.2.

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Facebook Like, Share and Retweet buttons in your WordPress

Posted on June 2, 2010 | 5 Comments

Hey man, I’m really busy at the moment, but it took me unnecessarily long to get those really hip facebook like, facebook share and retweet buttons everywhere on my blog, so I thought I’d try and save you some time by dropping a quick note on how I did it.

Adding the Facebook Like button functionality wasted the most time, because there are far too many plugins and howtos that claim to work and don’t quite. I ended up using the Like plugin (official wordpress page and plugin website), because it has the best documentation that includes details on all the ways in which things can go wrong, and there are many.  I’m using the IFRAME option, also because that seems to work most of the time.  I had a hard time finding this plugin in the built-in directory, so I downloaded and installed it manually.

For the facebook share button, I use the Facebook Share (New) Button plugin, and for the retweet button, I’m using the Topsy Retweet Button plugin.  I installed both of them from the built-in “Plugins | Add New” directory.

In all three cases, I made use of the plugin options to have the buttons placed all over my blog, instead of manually editing the theme.

I hope that you enjoy your shiny buttons, and I look forward to seeing you for the next Weekly Head Voices!

P.S. feel free to click on my buttons, right below this post.

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An Even More Ultimate Boot Disk!

Posted on May 24, 2010 | Leave a comment

In this short howto, I show you how to combine the Ultimate Boot CD (UBCD) with both Knoppix 6.2.1 and Ubuntu 10.04 onto a single USB stick to create An Even More Ultimate Boot Disk (EMUBD)!

UBCD is a bootable CD image that’s fantastic if you’re trying to save grandma’s PC from a certain death, as it contains a number of different bootable utilities for testing memory, testing and low-level repair of hard drives, partition repair, antivirus and so forth. It even contains Parted Magic, a compact linux distribution for fixing partitions, amongst others.

Knoppix is the swiss knife of live linux distributions, and Ubuntu 10.04 is probably the slickest distribution out there at the moment. Both of these can be ran live from your USB disc, so they don’t have to touch your hard drive.  However, both of them are also able to install to your hard disc if you so choose.

To me it seemed logical to combine all three of these elements onto the single USB flash drive that I carry on my keychain, as I know of many grandmas with broken PCs…

Let’s go!

  1. make sure the single FAT32 partition on your USB stick is bootable (use command ‘a’ in linux fdisk) and large enough (you’ll need just a bit less than 2G).
  2. mount your flash drive on a directory, henceforth referred to as FLASH_MNT.
  3. copy all files from the ubcd5 iso into a directory, henceforth referred to as CUSTOM_UBCD5.
  4. mount the ubuntu 10.04 i386 iso on a directory, henceforth referred to as LUCID_MNT
  5. mount the knoppix iso on a directory, henceforth referred to as KNOPPIX_MNT.
  6. copy necessary boot files from the ubuntu ISO to UBCD: 
    mkdir CUSTOM_UBCD5/ubcd/custom/lucid
cp LUCID_MNT/casper/vmlinuz LUCID_MNT/casper/initrd.lz CUSTOM_UBCD5/ubcd/custom/lucid
  7. copy ubuntu-10.04-desktop-i386.iso to your flash disk: 
    mkdir /FLASH_MNT/isos
cp ubuntu-10.04-desktop-386.iso /FLASH_MNT/isos/
  8. Knoppix can’t be booted directly from its iso like Ubuntu, so we have to copy the actual contents of the ISO to your flash: 
    cp -r KNOPPIX_MNT/KNOPPIX to FLASH_MNT/
cp -r KNOPPIX_MNT/boot/isolinux to FLASH_MNT/KNOPPIX/isolinux
  9. replace FLASH_MNT/KNOPPIX/isolinux/isolinux.cfg with the isolinux.cfg at the bottom of this post. (It’s the same file, except that “KERNEL linux” is replaced with “KERNEL /KNOPPIX/isolinux/linux”, “initrd=minirt.gz” with “initrd=/KNOPPIX/isolinux/minirt.gz”, F1, F2, F3 and DISPLAY paths all fixed, e.g. “F2 f2″ becomes “F2 /KNOPPIX/f2″ and finally all instances of “quiet” removed)
  10. Now replace CUSTOM_UBCD5/ubcd/custom/custom.cfg with the custom.cfg at the bottom of this post.
  11. copy all files from CUSTOM_UBCD5 to your usb flash disk: 
    cp -r CUSTOM_UBCD5/* FLASH_MNT/
  12. Finally, make the whole thing bootable with the following invocation. It’s really important that you replace /dev/sdX1 with the correct device for your flash disk. To see what this is, type “mount” and see the device associated with your FLASH_MNT. 
    cd FLASH_MNT
sudo ./ubcd/tools/linux/ubcd2usb/syslinux -s -d /boot/syslinux /dev/sdX1

You’re done. You should now be able to boot with your EMUBD! Knoppix and Ubuntu can be found under “User defined”.

Here are those files that you’ll need. First FLASH_MNT/KNOPPIX/isolinux/isolinux.cfg:

DEFAULT knoppix
APPEND ramdisk_size=100000 lang=en vt.default_utf8=0 apm=power-off vga=0x311 initrd=/KNOPPIX/isolinux/minirt.gz nomce loglevel=0 tz=localtime
TIMEOUT 50
# TOTALTIMEOUT 20
# KBDMAP german.kbd
PROMPT 1
F1 /KNOPPIX/isolinux/boot.msg
F2 /KNOPPIX/isolinux/f2
F3 /KNOPPIX/isolinux/f3
DISPLAY /KNOPPIX/isolinux/boot.msg
LABEL adriane
KERNEL /KNOPPIX/isolinux/linux
APPEND ramdisk_size=100000 lang=en vt.default_utf8=0 apm=power-off vga=0x311 initrd=/KNOPPIX/isolinux/minirt.gz nomce loglevel=0 tz=localtime adriane
LABEL knoppix
KERNEL /KNOPPIX/isolinux/linux
APPEND ramdisk_size=100000 lang=en vt.default_utf8=0 apm=power-off vga=791 initrd=/KNOPPIX/isolinux/minirt.gz nomce loglevel=0 tz=localtime
LABEL fb1024x768
KERNEL /KNOPPIX/isolinux/linux
APPEND ramdisk_size=100000 lang=en vt.default_utf8=0 apm=power-off vga=791 xmodule=fbdev initrd=/KNOPPIX/isolinux/minirt.gz nomce loglevel=0 tz=localtime
LABEL fb1280x1024
KERNEL /KNOPPIX/isolinux/linux
APPEND ramdisk_size=100000 lang=en vt.default_utf8=0 apm=power-off vga=794 xmodule=fbdev initrd=/KNOPPIX/isolinux/minirt.gz nomce loglevel=0 tz=localtime
LABEL fb800x600
KERNEL /KNOPPIX/isolinux/linux
APPEND ramdisk_size=100000 lang=en vt.default_utf8=0 apm=power-off vga=788 xmodule=fbdev initrd=/KNOPPIX/isolinux/minirt.gz nomce loglevel=0 tz=localtime
LABEL memtest
KERNEL memtest
APPEND foo
LABEL dos
KERNEL memdisk
APPEND initrd=balder.img
LABEL failsafe
KERNEL /KNOPPIX/isolinux/linux
APPEND ramdisk_size=100000 lang=en vt.default_utf8=0 vga=normal atapicd nosound noapic nolapic noacpi pnpbios=off acpi=off nofstab noscsi nodma noapm nousb nopcmcia nofirewire noagp nomce nonetwork nodhcp xmodule=vesa initrd=/KNOPPIX/isolinux/minirt.gz

… and then CUSTOM_UBCD5/ubcd/custom/custom.cfg:

MENU INCLUDE /ubcd/menus/syslinux/defaults.cfg
UI /boot/syslinux/menu.c32

# option to be able to go back to the main menu
LABEL -
MENU LABEL ..
COM32 /boot/syslinux/menu.c32
APPEND /ubcd/menus/syslinux/main.cfg

# this clause will boot directly from the ubuntu iso
LABEL ubuntulive
MENU LABEL Ubuntu 10.04 i386 Desktop LIVE
LINUX /ubcd/custom/lucid/vmlinuz
INITRD /ubcd/custom/lucid/initrd.lz
APPEND boot=casper iso-scan/filename=/isos/ubuntu-10.04-desktop-i386.iso --

# and this one will chain into the knoppix boot setup
LABEL knoppix
MENU LABEL Knoppix 6.2.1 LIVE
CONFIG /KNOPPIX/isolinux/isolinux.cfg

Post scriptum

  • The instructions in this post are derived from the UBCD linux documentation and various forum posts.  Credits to their authors!
  • If you don’t want Knoppix on your bootable USB and you have a Windows computer, you could also use MultiBootISOS to add multiple ISOs to a USB boot disk.

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Convert Word tables to EPS for inclusion in LaTeX

Posted on May 23, 2010 | 4 Comments

You might want to skip this post if any of the following is true:

  • You don’t know what LaTeX is.
  • You don’t care about typesetting theses.
  • You’re just generally low on Nerd midi-chlorians.

Recently, we (Mr Cricket and I) helped a good friend (argh, he might already have an acronym assigned,  I should make a glossary for this blog…) typeset his PhD thesis in LaTeX. Sounds straight-forward, were it not for the fact that most of the material was in MS Word to start off with. :)

It mostly comes down to a simple but laborious process of of taking one LaTeX PhD thesis framework (mine) and copy-pasting loads of text from Word into LaTeX, taking care to sprinkle with sufficient amounts of markup.  There are two slightly more complicated issues: The first is correctly converting figures, taking care to save bitmaps as PNGs (these will be converted to EPS via JPG later) and vector graphics as EPS.  I’ve written before about how to convert Visio to EPS for inclusion to LaTeX.

This quick post is concerned with the second problem: What is the best way to go about converting tables from Word to LaTeX?  Seeing that this was in actual fact the second PhD thesis I had converted from Word to LaTeX, including numerous tables, I have by now burnt my fingers on 68 different occasions, each time in an excruciating new and interesting way!  I’d like to spare you that pain, so here is, without (too much) further ado, the Best Way to Convert Word Tables to EPS for Inclusion into LaTeX!

No, we we are definitely NOT going to recode all Word tables in LaTeX markup, because that would be anti-social.  Instead, we are going to print all tables to EPS, then autocrop them and then simply include them into LaTeX via the includegraphics call inside of a normal table float.  Ok?

Here we go:

  1. Install PDFCreator.
  2. Select the table you want to convert in Word, then select “Print Selection” and select PDFCreator as the destination printer.
  3. Select the “Properties” button on the print dialog, then “Advanced”, “PostScript Options”, set “PostScript Output Option” to “Encapsulated PostScript (EPS)”
  4. Now print to file.
  5. Copy the output file to a linux machine (or use a live CD with ps2eps) and do the following: 
    ps2eps -B -C -l < printed_output.prn > result_cropped.eps
  6. You can now include result_cropped.eps in your LaTeX document with the following code: 
    \begin{table}
\begin{center}
\caption{Your table's caption}
\includegraphics{result_cropped.eps}
\label{tab:your_label}
\end{center}
\end{table}

If you took care to match the font you used in Word with your LaTeX font, people will probably not even realise that your tables are not LaTeX-native. That’s a clear-cut case of maximum Nerd street-cred with the minimum of actual fuss…

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