Re: Visual Sensors

Hi,

Please be careful. There are no guarantees on exact color levels. Color 
values in OpenGL rendering are not guarantee by the OpenGL standard. 
Hence, you may experience slightly different color level depending if 
you run Webots in 16 bbp or 32 bbp. Moreover, it also depend on your 
graphics card and OpenGL driver, so please use a robust vision algorithm 
to handle the fact that OpenGL makes no guarantee on the exact pixel 
value. The only thing I can say is that I am running the contest under 
Linux with a GeForce II MX graphics card and nVidia graphics driver 
1.0-4363 at 16 bbp. You can use screenshots from the web site (webcam) 
to get an idea on pixel values on the server, or save them into your 
memory.dat file to check if they differ from your local machine. In 
practise these values may differ by a small amount only. So avoid doing 
such testing:

if (my_red_level[i][j]==2312)  {...

rather do:

if (my_red_level[i][j]>2300 && my_red_level[i][j]<2320) {...

which is more robust and safer...

-Olivier

mrcbrr wrote:

>hi,
>my robot Sonovabic relies on visual sensors for initiation of some 
>actions. it seems like the arena on the server either uses different 
>colors(?? looks the same to me, even after analysing the image in a 
>paint-program i could not find a difference ??) or that he can't 
>perform his test of the visual data. some very weird thinqs occured 
>during the matches due to this (lying down after walking into 
>roybatty was the weirdest). A bit frustrating as these kinds of 
>problems never occured in any of the countless fights i tried at 
>home.
>
>what worked, was detecting the edge of the ring, but that might of 
>been a coincidence, as roybatty was also mistaken for the edge 
>(although he was the blue robot). only that obviously the threshhold 
>is higher than i had hoped :) ? 0.5 is the limit?
>  
>


------------------------ Yahoo! Groups Sponsor ---------------------~-->
Buy Ink Cartridges or Refill Kits for your HP, Epson, Canon or Lexmark
Printer at MyInks.com. Free s/h on orders $50 or more to the US & Canada.
http://www.c1tracking.com/l.asp?cid=5511
http://us.click.yahoo.com/mOAaAA/3exGAA/qnsNAA/pU_rlB/TM
---------------------------------------------------------------------~->

To unsubscribe from this group, send an email to:
[email protected]

 

Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/