On 4/6/2018 1:56 PM, clipka wrote:
> Am 06.04.2018 um 19:20 schrieb Mike Horvath:
>> I'm trying to capture a shadow of an object that I will later process in
>> GIMP. I want the shadow to be perfectly black, and the rest of the image
>> to be perfectly white. (A bit of anti-aliasing is fine.)
>>
>> How can I accomplish this? I have a white plane, but it ends up slightly
>> darker than white. Also, the shadow is a bit lighter than black.
> 
> There are a couple of factors that may contribute to your white plane
> not looking Pearly White(tm):
> 
> (1) The pigment may be non-white. Make sure to use `rgb 1`.
> 
> (2) The `diffuse` parameter may be set too low. Make sure to use
> `diffuse 1` (and while I normally advocate using `diffuse albedo FLOAT`,
> in this particular context I deliberately don't).
> 
> (3) The light source may not be directly overhead. In that case, make
> sure to use `brilliance 0` in the finish.
> 
> Alternatively, just crank up the light source brightness to some
> insanely high value ;)
> 
> 
> As for the shadow not looking pitch black, this is most certainly due to
> the `ambient` setting. Make sure to use `ambient 0`. (Also, make sure
> you are not using radiosity.)
> 


The `ambient` of the plane is 0, and the light source is `rgb 1`.

I did not know about changing `brilliance`. That seems to have fixed the 
problem, too.

Thanks!


Mike

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