[Radiance-general] Radiance output not satisfying radiosity equations

[Greg Ward]

Suggest using -dt 0 if you are computing many ambient bounces.

-Greg

> From: Andrew McNeil <amcneil at lbl.gov>
> Subject: Re: [Radiance-general] Radiance output not satisfying radiosity equations
> Date: September 25, 2014 10:25:21 AM PDT
> 
> Edward,
> 
> When I create ground truth renderings I pay close attention to the following parameters:
> -aa 0 
> -ad very high (like 10,000 - 50,000)
> -lw between 1/ad and 1/ad^3
> 
> Also, if you're using large area illumination sources, use the glow material instead of light material. If you're use light material for small area sources pay attention to the direct sampling parameters (-d?).
> 
> Andy
> 
> 
> On Wed, Sep 24, 2014 at 3:04 PM, Edward Zhang <edzhang at cs.washington.edu> wrote:
> Hi,
> 
> I'm working on an inverse rendering project and we're using Radiance to generate synthetic data for validation. Given a scene with diffuse surfaces, we're using the radiosity formulation as the core of our inverse process, namely that at any given scene point:
> 
> radiosity at point = (reflectance at point) x sum_over_scene_points(radiosity at scene point x form factor between points)
> 
> The sum is calculated using a hemicube method (with suitably high resolution) and the radiosities are obtained from reprojecting the .hdr outputs of Radiance onto the scene geometry.
> 
> My problem is that even in simple box scenes this equation doesn't hold. Most of the time, the reflectance estimated from this equation is too low. I've used enough ambient bounces that the Radiance output has converged, but I'm wondering if there are other Radiance rendering options that might be causing these problems.
> 
> Thanks for your help!
> 
> Edward
> 
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