Computer graphic system and computer-implemented method for generating images using a ray tracing methodology that makes use of a ray tree generated using low-discrepancy sequences and ray tracer for use therewith

摘要

A ray tracer generates a ray tree, the ray tree comprising a primary ray shot along a selected direction and a plurality of other rays, the other rays being generated by recursive splitting. A ray is split when it encounters a predetermined condition, and each of the rays into which it is split is directed directed along a selected direction. The ray tracer comprises a low-discrepancy sequence generator an condition detector and a ray generator. The low-discrepancy sequence generator is configured to generate elements of at least one low-discrepancy sequence. The condition detector is configured to determine, for one of the rays in the ray tree, whether the one of the rays encounters the predetermined condition. The ray generator is configured to, when the condition detector makes a positive determination in connection with the one of the rays, generate a selected number “M” of split rays each along a splitting direction determined by a respective direction value determined in accordance with; $$ {\left(y_{i,j}\right)}_{j=0}^{M-1}=\left({\Phi }_{b_d}\left(i\right)\oplus \frac{j}{M},\dots ,{\Phi }_{b_{d+\Delta d-1}}\left(i\right)\oplus {\Phi }_{b_{d+\Delta d-2}}\left(j\right)\right),\mathrm{where}$$ $$ \left\{{\Phi }_{b_d}\left(i\right),\dots ,{\Phi }_{b_{d+\Delta d-1}}\left(i\right)\right\}\mathrm{and}\left\{\frac{j}{M},\dots ,{\Phi }_{b_{d+\Delta d-2}}\left(j\right)\right\}$$are low-discrepancy sequences, for selected bases b and dimensions Δd, generated by the low-discrepancy sequence generator, and where ⊕ represents addition modulo “one” and “i” is an instance number in connection with the one of the rays.