[Radiance-general] splitting a render by light sources - rtcontrib

[william reynolds]

Greg
Thanks for your help. I will play with the -dj settings to get a better 
picture.

as for the spotlight type light, i am still at the "pretty basic" stage 
with my model - i will hopefully use real lighting fixture specs to 
model real instruments in the not too distant future! having said that, 
i dont really follow waht you mean by "set the cut-off past the natural 
cut- off of the fixture". could you explain a bit more please.

thanks once again
will


Gregory J. Ward wrote:
> Hi Will,
> 
> The reason you are seeing jagged edges to your spot is because the  
> default "direct jitter" or "-dj" setting for rtcontrib is 0.5.  (You  
> may discover all the default values by typing "rtcontrib - defaults".)  
> For spotlight's, the edges can be particularly strong,  and I don't 
> generally recommend this type unless you couple it with a  light output 
> distribution and set the cut-off past the natural cut- off of the 
> fixture -- unless of course you are simply going for an  artistic effect.
> 
> The -u+ option is recommended for rtcontrib, particularly when you  are 
> using it to render images, because the correlations between  values will 
> show up in odd ways on a 2-D image that would not be  noticeable in a 
> 1-D sample sequence.  This is why your original  rendering looks so odd.
> 
> As for the -e option of pfilt, it is used as an additional multiplier  
> if auto-exposure is employed with the default -2 (pass) operation, so  
> it is not completely overridden.
> 
> -Greg
> 
>> From: william reynolds <william.reynolds at oriel.ox.ac.uk>
>> Date: January 29, 2006 8:45:42 AM PST
>>
>> hi Greg
>>
>> theatre.pic is the image with the jagged edges. the optfile is  below 
>> from my post.
>>
>> I have also put on another image which I have just generated  (t2.pic, 
>> the command i generated it with is rtcontib_command, and  the opt 
>> fiale was theatre.opt), using the -u+ option to rtcontrib.  i gather 
>> this forces the use of purely mote carlo sampling, with no  
>> interpolation (is that right?). this seems to give a better image,  
>> but the edges (and indeed the areas in the scene lit entirely by  
>> interreflections) are very noisy. I have tried to reduce this by  
>> scaling down a large image and applying gaussian filtering to it  with 
>> pfilt, and although this helps it doesnt really fix the issue.
>>
>> let me know if there is anything else that i could send you to  help, 
>> and thanks very much for your help.
>>
>> regarding the exposure in pfilt - does the auto scaling factor  
>> overide a "-e 1" setting? i'm not sure i quite understand the bit  in 
>> the man page. it doesnt really matter to me, but im curious!
>>
>> thanks again, will
>>
> 
>