Unanswered Questions

I'm using a renderer developed by other people, and I found there are fireflies. It is strange that in a completely diffuse scene, there are still fireflies presented. To my understanding, I think it ...

I'm working on a (toy-level) path/ray-tracer, currently trying to implement (and understand) improved sampling strategies. The obvious next choice after uniform random sampling would be stratified/...

While I'll try my best to give all relevant info in all possible brevity below, please refer to the spoiler and link at the bottom of the post for the (more lengthy) original description if needed. ...

The increased radiance during sampling is known by: $$ L_s = L_e + \sigma_s \int p(w, w')f_p(w, w')dw' $$ The latter part, which accounts for in-scattering radiance bears a $\sigma_s$ in it. The ...

I'm trying to implement the multiple importance sampling path tracing, the MIS path tracing uses the MIS to combine the direct light sampling and brdf sampling to evaluate the direct lighting. The ...

To perform importance sampling on a light source, a probability density function must be provided for the sampling distribution. For most light sources, a valid probability distribution can be found, ...

I am trying to use the techniques discussed in this paper to implement a BTF into PBRT. I am stuck on how to actually interpolate the weights of the four closest sampling directions. At the BTF, I ...

Say $E_j$ is an estimator of the value $$I_j=\int f_j\:{\rm d}\lambda$$ of the $j$th pixel given by the path space integral of the corresponding measurement contribution function $f_j$. $f_j$ is of ...

According to Peter Shirely paper, one pdf(probability density function) can be defined for the union of the light sources and pick only one using a random number from this density: $$p(x) = \alpha_1 ...

I'm recently implementing Phong materials in my path tracer. My implementation of a randomly sampled Phong material works and looks fine. But it doesn't work well if the shininess(aka power) is too ...

I am looking for an algorithm (also ideas on possible directions are appreciated) which is able to compute the distribution of ellipses on a 2D surface in order to reach a good degree of covering. I ...

Equiangular sampling is a sampling method for point (sphere) emitter in scattering medium. While it claims to be very efficient when dealing with point (sphere) emitter in scattering medium (see this ...

PBRT 7.2.2 illustrates an example on requests sample dimensions in the same order: ...

As I understand it, the usual concept of a “material” in computer graphics, particularly 3D modeling, is a set of parameters (for example, color, specular reflectivity, IOR, light emission, etc.), ...

The paper "An Area-Preserving Parametrization for Spherical Rectangles" describes an efficient approach for sampling solid angles for rectangle light sources. I am wondering if The light ...