Am 24.06.2015 um 16:08 schrieb Thomas de Groot:

> That said, and in keeping with off off-topic, I have trouble with an
> emission sphere replacing a Sun light_source in a scene. Whatever the
> emission value, the scene remains fairly dark and no shadows seem to be
> cast. Using UberPOV. What about this, Christoph?

Using an emissive sphere instead of a light_source for the sun - while 
being proper PBR - is not a good idea performance-wise: The sun is quite 
small in the sky, and most rays will miss it. I suspect that's the 
underlying cause for your problem.

If that is the case, and you want to stick with the emissive sphere, then:

- In the radiosity block, use a second parameter to the "count" keyword, 
and make it huge; this will be the total number of directions the 
radiosity algorithm will choose from, yet for each individual sample it 
will only shoot as many of those as specified by the smaller parameter.

- In the radiosity block, increase the primary parameter to the "count" 
keyword.

- On the command line, use a higher oversampling confidene ("-ac") 
setting; this will force UberPOV to shoot more rays for any given pixel 
before it thinks it has seen it all.

The emission setting for the sun should probably be somewhere in the 1e5 
range.

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