[Radiance-general] rtrace -oo adds direction to origin

[Axel Jacobs]

Hi Greg,

> The -oo option and -od option report the origin and normalized ray
> direction (respectively), but only with -I-.  When you set -I+, then
> rtrace fudges the calculation by creating a ray 1 unit above an
> imaginary Lambertian surface, and this is why the origin (and
> direction if you check) do not match your input.  Instead, the
> intersection point (-op) and surface normal (-on or -oN) will match
> the origin and direction given.

This is baffling. I always used just plain -I, without +/-, and it worked.
I am indeed after illuminance.

Let me repeat this:
- rtrace -defaults: -i- (so illuminance is off, hence luminance)
- -i/-I is a boolean switch (or are they two independent boolean switches?)
- I have -I in my rtrace command line. This toggles the default, turning
it on.
- with i/I set to on, the origin should be set to the input, no?

> This is not a new bug in 3.7, but something that's been there since I
> enabled reports of parameters besides ray value with -I+ in the 2.3
> release.  Perhaps you weren't using the -I+ setting in your previous
> scripts.

No, just -I

> I think I could fix this behavior if it's really screwing you up.  I
> agree that it's confusing to have the -oo and -od options change
> their apparent reporting depending on the -I setting, but they are
> reporting the values on the ray actually traced.  You don't start out
> at the surface and direct the ray straight up in order to compute
> irradiance.  That wouldn't work.

I think I understand the subtlety of measuring luminance vs. illuminance,
so the added '1' and the inversed direction doesn't worry me. The
'toggling' is, though.

Thanks for your reply, anyhow.

Cheers

Axel