Week 01 - SAB Week

0107

My Unneeded Prescence

2nd SAB Meeting will be held in the Cove over the next two days (8^th, 9^th Jan), so everyone was taking turns using the Cove for preparations. The increased signs of activity along the corridor and in the Cove is an obvious indication that the SAB meeting must be a fairly important event. Amidst the temporal chaos, it was decided that it would be best for JL and I to be out of action the next two days. Peng is needed for the demo though.

Also, I have discovered the cause of the unresponsiveness in the Light Draw programs on my laptop. The culprit:

cvWaitKey(n)

After a few trials, I found the uncanny behaviour that the frame will not be rendered if the parameter n passed to cvWaitKey() is <= 1. Weird huh. I would attribute the root of the problem to my laptop (IBM T43 Thinkpad) not having less than 2 millisecond resolution timer, but I do not know this for a fact. The uber machine Light (where we ran our codes on) did not have this problem. Then again, I'm comparing my miserable Thinkpad with a 10,000 monster. (This also enforces my dev hypothesis that if I'm able to get things running smoothly on my laptop, then logically Light should not have any problems running the same program too.)

So, apparently cvWaitKey(1) was (and still is) used in the codes because cvWaitKey(30) was causing too much lag between rendering loops. This reminds me again of the problem that too much processing is done in one loop; rendering, fading, detection, trailing, memory operations etc. are done in one loop. Peng and JL are already looking into multithreading, but my previous experience with multithreading was generally negative. I was not able to control which thread to wake up next (in Java), and I have no control over what the scheduler does anyway. Could be due to my ignorance with multithreading, and I knew it would come back and bite me someday.


0108

My Fix: Artefacts appearing in lower/bottom right half of the screen. Config: ATI, SuSe 10.3

Setting

Option "XAANoOffscreenPixmaps" "true"

under

Section "Device"

in /etc/X11/xorg.conf should solve the problem. !!! Remember to backup xorg.conf first !!!

I've got my laptop running a few hours now, and the problem seems to be resolved. The occurrences are random, so I am not able to tell for sure.

Ref: http://wiki.sabayonlinux.org/index.php?title=Black_borders_around_windows_fix_(ATI)

0111

Friday the team had a morning meeting, we discussed about Light Draw's progress and also planned the next phase of development. Light Draw involves two aspects in general, that is HCI, and recognition. The latter should be our main focus for now, and we will have to explore methods to detect irregular shapes.

Got Peng to show me the student's quarters on the second level.

I tried to find out why Light Draw isn't as sensitive to Red channel. Tried messing with the individual colour channels, and with Peng's help I realised that it isn't enough to work in RGB color representation only. I was looking CT also mentioned that the problem is non-trivial. Will probably need get their help on this again.

Also, I had a go with the Wiimote Whiteboard program mentioned on post 0103, 0104. The setup is fuss free, except for the pairing between the Wiimote and the BlueSoliel program. Instead of holding Wiimote buttons 1 & 2 down while pairing, press the red button found in the battery compartment of the Wiimote. I tested the setup on my laptop and used a remote control instead of a infra-red pen. This gave me problems during calibration.

My first treat from Kevin! Kevin bought dinner today. Woohoo!


Misc stuff:

Draft N for my laptop! Got DWA140 USB dongle to work in Linux. The installation disc that came with the dongle supports only M$. Pffft.

Google tells me that the DWA140 uses the RT2870 chipset. Glad I don't have to open it up and void the warranty.

Download the RT2870 chipset driver at http://www.ralinktech.com/ralink/Home/Support/Linux.html

Some tweaks to the default installation required:

• Edit Makefile, replace /tftpboot with another path. e.g /opt/dlink/
  Default installation places tftpboot in root directory, which I did not like
• Follow instructions found in README_STA, would be a good idea to copy it from extracted folder to /opt/dlink/
• Modify os/linux/config.mk, set
  HAS_WPA_SUPPLICANT = y
  and
  HAS_NATIVE_WPA_SUPPLICANT_SUPPORT = y
• Copy the folders /os/linux to /opt/dlink/