a7283fc1d5
The distance sampling is mostly based on weighted delta tracking from [Monte Carlo Methods for Volumetric Light Transport Simulation] (http://iliyan.com/publications/VolumeSTAR/VolumeSTAR_EG2018.pdf). The recursive Monte Carlo estimation of the Radiative Transfer Equation is \[\langle L \rangle=\frac{\bar T(x\rightarrow y)}{\bar p(x\rightarrow y)}(L_e+\sigma_s L_s + \sigma_n L).\] where \(\bar T(x\rightarrow y) = e^{-\bar\sigma\Vert x-y\Vert}\) is the majorant transmittance between points \(x\) and \(y\), \(p(x\rightarrow y) = \bar\sigma e^{-\bar\sigma\Vert x-y\Vert}\) is the probability of sampling point \(y\) from point \(x\) following exponential distribution. At each recursive step, we randomly pick one of the two events proportional to their weights: * If \(\xi < \frac{\sigma_s}{\sigma_s+\vert\sigma_n\vert}\), we sample scatter event and evaluate \(L_s\). * Otherwise, no real collision happens and we continue the recursive process. The emission \(L_e\) is evaluated at each step. This also removes some unused volume settings from the UI: * "Max Steps" is removed, because the step size is automatically specified by the volume octree. There is a hard-coded threshold `VOLUME_MAX_STEPS` to prevent numerical issues. * "Homogeneous" is automatically detected during density evaluation An option "Unbiased" is added to the UI. When enabled, densities above the majorant are clamped.
65 lines
3.1 KiB
C++
65 lines
3.1 KiB
C++
/* SPDX-FileCopyrightText: 2011-2022 Blender Foundation
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*
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* SPDX-License-Identifier: Apache-2.0 */
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#include "scene/devicescene.h"
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#include "device/device.h"
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#include "device/memory.h"
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CCL_NAMESPACE_BEGIN
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DeviceScene::DeviceScene(Device *device)
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: bvh_nodes(device, "bvh_nodes", MEM_GLOBAL),
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bvh_leaf_nodes(device, "bvh_leaf_nodes", MEM_GLOBAL),
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object_node(device, "object_node", MEM_GLOBAL),
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prim_type(device, "prim_type", MEM_GLOBAL),
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prim_visibility(device, "prim_visibility", MEM_GLOBAL),
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prim_index(device, "prim_index", MEM_GLOBAL),
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prim_object(device, "prim_object", MEM_GLOBAL),
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prim_time(device, "prim_time", MEM_GLOBAL),
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tri_verts(device, "tri_verts", MEM_GLOBAL),
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tri_shader(device, "tri_shader", MEM_GLOBAL),
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tri_vnormal(device, "tri_vnormal", MEM_GLOBAL),
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tri_vindex(device, "tri_vindex", MEM_GLOBAL),
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curves(device, "curves", MEM_GLOBAL),
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curve_keys(device, "curve_keys", MEM_GLOBAL),
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curve_segments(device, "curve_segments", MEM_GLOBAL),
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points(device, "points", MEM_GLOBAL),
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points_shader(device, "points_shader", MEM_GLOBAL),
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objects(device, "objects", MEM_GLOBAL),
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object_motion_pass(device, "object_motion_pass", MEM_GLOBAL),
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object_motion(device, "object_motion", MEM_GLOBAL),
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object_flag(device, "object_flag", MEM_GLOBAL),
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object_prim_offset(device, "object_prim_offset", MEM_GLOBAL),
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camera_motion(device, "camera_motion", MEM_GLOBAL),
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attributes_map(device, "attributes_map", MEM_GLOBAL),
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attributes_float(device, "attributes_float", MEM_GLOBAL),
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attributes_float2(device, "attributes_float2", MEM_GLOBAL),
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attributes_float3(device, "attributes_float3", MEM_GLOBAL),
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attributes_float4(device, "attributes_float4", MEM_GLOBAL),
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attributes_uchar4(device, "attributes_uchar4", MEM_GLOBAL),
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light_distribution(device, "light_distribution", MEM_GLOBAL),
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lights(device, "lights", MEM_GLOBAL),
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light_background_marginal_cdf(device, "light_background_marginal_cdf", MEM_GLOBAL),
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light_background_conditional_cdf(device, "light_background_conditional_cdf", MEM_GLOBAL),
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light_tree_nodes(device, "light_tree_nodes", MEM_GLOBAL),
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light_tree_emitters(device, "light_tree_emitters", MEM_GLOBAL),
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light_to_tree(device, "light_to_tree", MEM_GLOBAL),
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object_to_tree(device, "object_to_tree", MEM_GLOBAL),
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object_lookup_offset(device, "object_lookup_offset", MEM_GLOBAL),
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triangle_to_tree(device, "triangle_to_tree", MEM_GLOBAL),
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particles(device, "particles", MEM_GLOBAL),
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svm_nodes(device, "svm_nodes", MEM_GLOBAL),
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shaders(device, "shaders", MEM_GLOBAL),
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lookup_table(device, "lookup_table", MEM_GLOBAL),
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sample_pattern_lut(device, "sample_pattern_lut", MEM_GLOBAL),
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ies_lights(device, "ies", MEM_GLOBAL),
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volume_tree_nodes(device, "volume_tree_nodes", MEM_GLOBAL),
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volume_tree_roots(device, "volume_tree_roots", MEM_GLOBAL),
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volume_tree_root_ids(device, "volume_tree_root_ids", MEM_GLOBAL)
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{
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memset((void *)&data, 0, sizeof(data));
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}
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CCL_NAMESPACE_END
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