So right now I am at the IEEE Symposium on 3D User Interfaces in Singapore. We have a couple of publications which I’ll be posting over the next few days. First up is Adaptive Color Marker for SAR Environments. In a previous study we created interactive virtual control panels by projecting onto otherwise blank designs. We used a simple orange marker to track the position of the user’s finger. However, in a SAR environment, this approach suffers from several problems:
- The tracking system can’t track the marker if we project the same colour as the marker.
- Projecting onto the marker changes it’s appearance, causing tracking to fail.
- Users could not tell when they were pressing virtual controls, because their finger occluded the projection.
We address these problems with an active colour marker. We use a colour sensor to detect what is being projected onto the marker, and change the colour of the marker to an opposite colour, so that tracking continues to work. In addition, we can use the active marker as a form of visual feedback. For example, we can change the colour to indicate a virtual button press.
I’ve added the publication to my publications page, and here’s the video of the marker in action.
The Wearable Computer Lab has purchased 11 high performance computers featuring NVidia Quadro FX3800 Cards from Xenon Systems. These will be used to power the new specially designed Spatial Augmented Reality lab, created to support large scale augmented reality. Some details about the new lab can be found here.
An article in the Adelaide Advertiser from Saturday featured our lab director, Bruce Thomas. The article looks at the ways technology is going to infiltrate our everyday life in the future.
Just a quick note to say the Wearable Computer Lab was featured in an article in the Adelaide Advertiser yesterday. Michael in particular got his face in the paper. The explores the possibilities of Augmented Reality in the near future. For more information, see the media page, or just read the article.
This weekend I presented my paper, Augmented Foam Sculpting for Capturing 3D Models, at the International symposium on 3D user interfaces. Since the conference has passed, I have added the video to youtube and the paper to my publications page. First, the video, then some discussion after the jump.
The inspiration for this work came out of a project we did with some industrial design students. Their job was to create some input devices for my SAR Airbrushing system. First up, we had a meeting where I showed them a very early stages of development version of the system, to give them an idea of what we were doing. They went away and came up with ideas for input devices, and in the next meeting had a bunch of sketches ready. We discussed the sketches; what we liked and what we didn’t like. Next, they brought us foam mockups of some of the designs. We discussed these, and then eventually they came back with full CAD models ready for 3D printing. They did a great job by the way. But it got us thinking:
How can we make this process better?
Augmented Foam Sculpting is the result of this work. It allows a designer/artist to simultaneously create a physical design mockup and matching virtual model. This is a Good Thing™, because it utilises the skills and tools that designers are already using.
The system works by tracking the position and orientation of both the hot wire foam cutter, and the piece of foam the user is sculpting. We can track the motion of the hot wire as it passes through the foam. From there, we can create geometry that matches the cut path, and perform a Boolean difference operation on the foam geometry, to replicate the cut in the virtual model (Before any of you “Booleans are evil” people get to me, I’d like to point out I’m only dealing with, and creating, triangle meshes. There are no 11 sided polygons here).
Using projectors, we can add extra information to the foam as the user sculpts. We implemented 2 visualisations to aid designers when creating specific models. Cut Animation displays cuts to be made as animated lines on the foam surface. Once a cut has been made, the system moves to the next one. This visualisation could be used to recreate a previous object, or to instruct novices. An algorithm could be developed to calculate the actual cuts that need to be made, reducing the amount of planning needed when making an object.
The second visualisation, Target, projects a target model so that it appears to be inside the foam. The foam is coloured based on how much needs to be removed to match a target model. This could be used to create variations on a previous model.
Finally, we can use 3D procedural textures to change the appearance of the foam. For example, we implemented a wood grain 3D texture. This works pretty well, because as you cut away the foam, the texture updates to appear as though the wood was actually cut. 3D textures are also ideal because we don’t need to generate texture coordinates after each cut.
For all the details, please have a read of the paper. If you have any questions/comments/feedback/abuse, please comment on this post, or send me an email.
Recently I was working on a php command line program that required access to a serial port.
Initially developed under Linux the program was then shifted to it’s permanent location on a FreeBSD server. This is where we first started having problems. Initially we discovered the server didn’t have a native serial port. We fixed this using a USB to serial converter/dongle (FTDI Chipset). This was fine as FreeBSD has the ufdti kernel module. Upon loading the module new devices appears in /dev
crw-rw---- 1 uucp dialer 0, 157 Oct 6 08:39 /dev/cuaU0 crw-rw---- 1 uucp dialer 0, 158 Oct 6 08:39 /dev/cuaU0.init crw-rw---- 1 uucp dialer 0, 159 Oct 6 08:39 /dev/cuaU0.lock crw-rw-rw- 1 root wheel 0, 154 Jan 8 10:50 /dev/ttyU0 crw------- 1 root wheel 0, 155 Oct 6 08:39 /dev/ttyU0.init crw------- 1 root wheel 0, 156 Oct 6 08:39 /dev/ttyU0.lock
We attempted to connect to our device using screen (screen /dev/ttyU0 115200) and everything worked as expected. We could send AT commands to the device all ok.
We then stopped screen and ran our php program. It ended up hanging on a fgets call to the serial port. This is really strange we though.
Next we queried the port to find out what baud rate it was set at:
>stty -f /dev/ttyu0 speed 9600 baud; lflags: echoe echoke echoctl oflags: tab0 cflags: cs8 -parenb
Strange we thought as we’d just connected with screen at 115200. Under linux we use screen to set the baud rate, all other programs accessing the port use the port at 115200. So what had set it back to 9600 baud?
We tried to use stty to set the speed:
>stty -f /dev/ttyU0 speed 115200
>stty -f /dev/ttyu0 speed 9600 baud; lflags: echoe echoke echoctl oflags: tab0 cflags: cs8 -parenb
What on earth was happening? We set the speed to 115200 but directly quering the port again indicated it was still at 9600 baud? At this point we were perplexed.
Eventually we found the solution. The newer FreeBSD terminal drivers provide the *.init devices, in this case /dev/ttyU0.init . These devices indicate the terminal settings to be applied to the terminal when the device is closed. Whilst Linux leaves the device in the same state the last program put the port into, FreeBSD restores the terminals state to what ever is specified in the init file. So a quick command:
> stty -f /dev/ttyU0.init -icanon -isig -echo echoe echok echoke echoctl -icrnl -ixany -imaxbel ignpar -opost -onlcr -oxtabs cs8 -parenb -hupcl clocal
And then to check:
> stty -f /dev/ttyU0 speed 115200 baud; lflags: -icanon -isig -echo echoe echok echoke echoctl iflags: -icrnl -ixany -imaxbel ignpar oflags: -opost -onlcr -oxtabs cflags: cs8 -parenb -hupcl clocal
Excellent. The terminal was now configured exactly how we wanted. We ran the program and it worked like a charm!
The other day I was working with a few colleges using VNC. We came across an issue with our VNC setup. We could connect a VNC client (be it tightvnc, vncviewer, vinagre or x4vnclient) to our vnc server but never see anything on the screen. It was if the server was freezing or hanging. This left us wondering why. Initially we thought we had broken something in the VNC server – after all we had made code modifications. However the solution turned out to be a very simple fix.
You see the VNC protocol has the ability to place a client ONHOLD. During this state the clients events are not transmitted and the server sends back no images. This is what was happening to us. Normally the VNCServer will place the client on hold during a connection, asking the user to accept/reject the client. However we had been playing around with configuration files and set the prompt to disabled – we wanted automatic connection, with no prompt. Hence the VNCServer was placing the client on hold, noticed prompts were disabled and because authentication had not been established, sat there twiddling it’s thumbs.
A simple configuration file fix and everything was working again. Ironically at the same time we also discovered that modifying files by had in ~/.gconf/* doesn’t do anything as there’s a daemon that holds the configuration and it periodically writes to ~/.gconf/* overwriting any changes you might have made – hence we used gconftool2.
To allow gnome to prompt the user for authentication. Hence a dialog would show up and the authorisation could take place.
gconftool-2 -s -t bool /desktop/gnome/remote_access/prompt_enabled true
You can also find this same setting in gconf-editor if you want a gui way to update it.
One project I’ve been working on with fellow members of the Wearable Computer Lab (WCL) has been a project we’ve called ‘Snappy’. Snappy is simply an old Canon IXUS camera that is connected to an old Dell Laptop. It was setup to monitor the construction of a new building here at the University of South Australia. The building will be used for a number of things but in particular it will host the Visualisation Lab used by the WCL.
Snappy was something setup so the lab could see how construction was going and also so we could have some time lapse photography about the building being built.
Ironically, it appears that Snappy has grown. The VC of the Uni checks it, the architechs in Canberra are using it to monitor progress and a lot of the people involved are using it!
You see snappy consist of the camera and a web frontend to the photos snappy has taken. The frontend is a bunch of PHP scripts created by myself (Benjamin Close), Aaron Stafford, Ross Smith and Micheal Marner. Each one of us has worked on a part of either the scripts, the hardware or getting things working. Robert Speedie has been a big help in making this work as well. He has the contacts and funding to help it happen.
So if your interested in seeing Snappy, visit the url:
and have a look. One of the photos he’s taken is below – a great sunrise.
Recently Ben and I have been trying to get a FreeBSD box to join an Active Directory domain. The domain controller was running Windows Server 2008. After a *lot* of stuffing around to get this working we finally found the solution to our problem – the version of samba.
You see the problem we were facing was:
# net ads join -U cis-closebs cis-closebs's password: Failed to join domain: Improperly formed account name
Now we checked the logs, checked kerberos, samba, but could not get this working. The debug logs showed something but nothing really useful:
# net ads join -U cis-closebs cis-closebs's password: Failed to join domain: Improperly formed account name # net ads join -d 3 -U cis-closebs [2009/02/02 12:55:26, 3] param/loadparm.c:lp_load(5031) lp_load: refreshing parameters [2009/02/02 12:55:26, 3] param/loadparm.c:init_globals(1430) Initialising global parameters [2009/02/02 12:55:26, 3] param/params.c:pm_process(572) params.c:pm_process() - Processing configuration file "/usr/local/etc/smb.conf" [2009/02/02 12:55:26, 3] param/loadparm.c:do_section(3770) Processing section "[global]" [2009/02/02 12:55:26, 2] lib/interface.c:add_interface(81) added interface ip=188.8.131.52 bcast=184.108.40.206 nmask=255.255.254.0 [2009/02/02 12:55:26, 3] libsmb/namequery.c:get_dc_list(1489) get_dc_list: preferred server list: "220.127.116.11, uninet.unisa.edu.au, *" [2009/02/02 12:55:26, 3] libads/ldap.c:ads_connect(394) Connected to LDAP server 18.104.22.168 [2009/02/02 12:55:26, 3] libsmb/namequery.c:get_dc_list(1489) get_dc_list: preferred server list: "22.214.171.124, uninet.unisa.edu.au, *" [2009/02/02 12:55:26, 3] libsmb/namequery.c:get_dc_list(1489) get_dc_list: preferred server list: "126.96.36.199, uninet.unisa.edu.au, *" cis-closebs's password: [2009/02/02 12:55:27, 3] libsmb/namequery.c:get_dc_list(1489) get_dc_list: preferred server list: "188.8.131.52, uninet.unisa.edu.au, *" [2009/02/02 12:55:27, 3] libads/ldap.c:ads_connect(394) Connected to LDAP server 184.108.40.206 [2009/02/02 12:55:27, 3] libads/sasl.c:ads_sasl_spnego_bind(213) ads_sasl_spnego_bind: got OID=1 2 840 48018 1 2 2 [2009/02/02 12:55:27, 3] libads/sasl.c:ads_sasl_spnego_bind(213) ads_sasl_spnego_bind: got OID=1 2 840 113554 1 2 2 [2009/02/02 12:55:27, 3] libads/sasl.c:ads_sasl_spnego_bind(213) ads_sasl_spnego_bind: got OID=1 2 840 113554 1 2 2 3 [2009/02/02 12:55:27, 3] libads/sasl.c:ads_sasl_spnego_bind(213) ads_sasl_spnego_bind: got OID=1 3 6 1 4 1 311 2 2 10 [2009/02/02 12:55:27, 3] libads/sasl.c:ads_sasl_spnego_bind(222) ads_sasl_spnego_bind: got server principal name = not_defined_in_RFC4178@please_ignore [2009/02/02 12:55:27, 3] libsmb/clikrb5.c:ads_krb5_mk_req(593) ads_krb5_mk_req: krb5_cc_get_principal failed (No such file or directory) [2009/02/02 12:55:27, 1] libsmb/clikrb5.c:ads_krb5_mk_req(602) ads_krb5_mk_req: krb5_get_credentials failed for not_defined_in_RFC4178@please_ignore (Server not found in Kerberos database) [2009/02/02 12:55:27, 1] utils/net_ads.c:net_ads_join(1470) error on ads_startup: Server not found in Kerberos database Failed to join domain: Improperly formed account name [2009/02/02 12:55:27, 2] utils/net.c:main(1036) return code = -1
Turns out that it was the version of samba we were using. Version 3.0.28 had issues with joining a Windows Server 2008 Active Directory domain. This was fixed in Samba 3.0.28a and as can be seen with the FreeBSD ports commit:
Revision 1.169: download – view: text, markup, annotated – select for diffs
Update port to the 3.0.28a revision. Major changes: o Failure to join Windows 2008 domains o Windows Vista (including SP1 RC) interop issues Approved by: shaun (mentor, implicit)
So if you find yourself hunting around chasing something that surely should work.. consider upgrading samba!