Re: [simspark-devel] discussion

[Oliver O. <Oli...@ne...>]

Hi Hesham ;-)

On 06/02/2007, at 2:24 PM, Hesham wrote:

> Yes, he was. Just could you please do me a favour and let me know  
> what you expect from the logger. I have just a simple idea, maybe  
> it works or maybe not. What's your opinion about LOD (level of  
> detail)? IMHO when an object (agent) is not close to the ball  
> logging its exact movement frame by frame isn't necessary.

The created logfile should be useful for somebody developing robots,  
and (if possible) also useful to show a match just to see it.

Reducing the LOD, when something is not so important, is of course  
possible, but at the moment I'm not so sure what kind of information  
you would discard when the LOD is not so high. For example, could be  
you don't update less interesting objects in between "keyframes".  
Have you been thinking of something like this?

Also, when you do experiments at home, the focus might not alway be  
on the player close to the ball, so LOD could be difficult here. At  
least, it should be easy to disable it for research and debugging  
issues.

right now, we're logging everything in text format. This is nice  
because it's still human readable, and it's not totally bad in terms  
of entropy (just using binary could be worse, especially if we don't  
need to have many (decimal) places after the dot). The format could  
also be better than text format, however, because in text format,  
we're using only a few characters out of all possible usable ones. So  
one approach would be to round the decimal numbers to, say, 2 places  
after the dot, multiply by 128 (or something which fits to the  
rounding), and transmit the number as 2 or 3 byte integer. By this it  
would be (maybe) possible to come up with a more compact format for  
logfiles. If you really want to do bitcounting, you can also use  
parts of a byte for smaller numbers (e.g. 12 bits for degrees or  
something like that), but that's maybe too much already.

A more intelligent version  of the keyframe idea would be to log only  
in between the keys when a body doesn't behave as expected, so that  
cases where you don't log an interpolation / extrapolation would do a  
good job. I guess that's a bit challenging, though.

cheers
Oliver

-- 
Oliver Obst          ES208   form follows function (Louis Sullivan).
Fon: +61 2 492 16175                          http://oliver.obst.eu/
Uni Newcastle  School of Electrical Engineering and Computer Science