[Radiance-general] Illuminance calculation on a virtual surface?

[gward at lmi.net]

OK, Rob -- you got me.  Your little trick would work.  I don't think he
really needs it, though, since he already has a method for generating
the grid points for rtrace.  He can simply increase the resolution of
the grid he already has (as Raphael suggested) and/or upsample the
result using pfilt.  Or your method.  All will work.

-Greg

Quoting Rob Guglielmetti <rpg at rumblestrip.org>:

> Hi Greg, Hi John,
> 
> Greg Ward wrote:
> 
> > No good.  Trans gets ignored by the rpict -i option.  Just use pfilt to 
> > scale the illuminance map if it's not big enough.  (John M's suggestion 
> > -- he's sitting next to me in Leicester.)
> 
> Oh yeah?  =8-p
> 
> vwrays -x XRES -y YRES -vf viewfile -fd | rtrace -h -fd -opn octree \
> | rtrace -fdc -I render_options -x XRES -y YRES octree > illum_picture.pic
> 
> Greg, does this look familiar?  A little ditty from a year or so ago? 
> You sent me this tip when I asked you how to get illuminance on a 
> building's curtain wall.  The first rtrace computes the intersection 
> point (which is fast) and the second rtrace does the illuminance 
> calculation.  Cool, yes?  Yes.
> 
> Now, given this little tip, could he use trans as I described?
>