Cycles: volume sampling method can now be set per material/world.

This gives you "Multiple Importance", "Distance" and "Equiangular" choices.

What multiple importance sampling does is make things more robust to certain
types of noise at the cost of a bit more noise in cases where the individual
strategies are always better.

So if you've got a pretty dense volume that's lit from far away then distance
sampling is usually more efficient. If you've got a light inside or near the
volume then equiangular sampling is better. If you have a combination of both,
then the multiple importance sampling will be better.
This commit is contained in:
Brecht Van Lommel 2014-06-07 18:47:14 +02:00
parent a29807cd63
commit 5fa68133c9
10 changed files with 112 additions and 51 deletions

@ -108,10 +108,10 @@ enum_integrator = (
('PATH', "Path Tracing", "Pure path tracing integrator"),
)
enum_volume_homogeneous_sampling = (
('DISTANCE', "Distance", "Use Distance Sampling"),
('EQUI_ANGULAR', "Equi-angular", "Use Equi-angular Sampling"),
('MULTIPLE_IMPORTANCE', "Multiple Importance", "Combine distance and equi-angular sampling"),
enum_volume_sampling = (
('DISTANCE', "Distance", "Use distance sampling, best for dense volumes with lights far away"),
('EQUIANGULAR', "Equiangular", "Use equiangular sampling, best for volumes with low density with light inside or near the volume"),
('MULTIPLE_IMPORTANCE', "Multiple Importance", "Combine distance and equi-angular sampling for volumes where neither method is ideal"),
)
@ -147,13 +147,6 @@ class CyclesRenderSettings(bpy.types.PropertyGroup):
default='PATH',
)
cls.volume_homogeneous_sampling = EnumProperty(
name="Homogeneous Sampling",
description="Sampling method to use for homogeneous volumes",
items=enum_volume_homogeneous_sampling,
default='DISTANCE',
)
cls.use_square_samples = BoolProperty(
name="Square Samples",
description="Square sampling values for easier artist control",
@ -237,7 +230,7 @@ class CyclesRenderSettings(bpy.types.PropertyGroup):
name="Volume Samples",
description="Number of volume scattering samples to render for each AA sample",
min=1, max=10000,
default=1,
default=0,
)
cls.sampling_pattern = EnumProperty(
@ -603,6 +596,12 @@ class CyclesMaterialSettings(bpy.types.PropertyGroup):
"(not using any textures), for faster rendering",
default=False,
)
cls.volume_sampling = EnumProperty(
name="Volume Sampling",
description="Sampling method to use for volumes",
items=enum_volume_sampling,
default='DISTANCE',
)
@classmethod
def unregister(cls):
@ -673,6 +672,12 @@ class CyclesWorldSettings(bpy.types.PropertyGroup):
"(not using any textures), for faster rendering",
default=False,
)
cls.volume_sampling = EnumProperty(
name="Volume Sampling",
description="Sampling method to use for volumes",
items=enum_volume_sampling,
default='EQUIANGULAR',
)
@classmethod
def unregister(cls):

@ -176,16 +176,11 @@ class CyclesRender_PT_volume_sampling(CyclesButtonsPanel, Panel):
scene = context.scene
cscene = scene.cycles
split = layout.split(align=True)
sub = split.column(align=True)
sub.label("Heterogeneous:")
sub.prop(cscene, "volume_step_size")
sub.prop(cscene, "volume_max_steps")
sub = split.column(align=True)
sub.label("Homogeneous:")
sub.prop(cscene, "volume_homogeneous_sampling", text="")
row = layout.row()
row.label("Heterogeneous:")
row = layout.row()
row.prop(cscene, "volume_step_size")
row.prop(cscene, "volume_max_steps")
class CyclesRender_PT_light_paths(CyclesButtonsPanel, Panel):
@ -829,8 +824,6 @@ class CyclesWorld_PT_volume(CyclesButtonsPanel, Panel):
world = context.world
panel_node_draw(layout, world, 'OUTPUT_WORLD', 'Volume')
layout.prop(world.cycles, "homogeneous_volume")
class CyclesWorld_PT_ambient_occlusion(CyclesButtonsPanel, Panel):
bl_label = "Ambient Occlusion"
@ -922,15 +915,24 @@ class CyclesWorld_PT_settings(CyclesButtonsPanel, Panel):
cworld = world.cycles
cscene = context.scene.cycles
col = layout.column()
split = layout.split()
col.prop(cworld, "sample_as_light")
sub = col.row(align=True)
col = split.column()
col.label(text="Surface:")
col.prop(cworld, "sample_as_light", text="Multiple Importance")
sub = col.column(align=True)
sub.active = cworld.sample_as_light
sub.prop(cworld, "sample_map_resolution")
if cscene.progressive == 'BRANCHED_PATH':
sub.prop(cworld, "samples")
col = split.column()
col.label(text="Volume:")
col.prop(cworld, "volume_sampling", text="")
col.prop(cworld, "homogeneous_volume", text="Homogeneous")
class CyclesMaterial_PT_preview(CyclesButtonsPanel, Panel):
bl_label = "Preview"
@ -979,8 +981,6 @@ class CyclesMaterial_PT_volume(CyclesButtonsPanel, Panel):
panel_node_draw(layout, mat, 'OUTPUT_MATERIAL', 'Volume')
layout.prop(cmat, "homogeneous_volume")
class CyclesMaterial_PT_displacement(CyclesButtonsPanel, Panel):
bl_label = "Displacement"
@ -1023,10 +1023,18 @@ class CyclesMaterial_PT_settings(CyclesButtonsPanel, Panel):
col.label()
col.prop(mat, "pass_index")
col = layout.column()
col.prop(cmat, "sample_as_light")
split = layout.split()
col = split.column()
col.label(text="Surface:")
col.prop(cmat, "sample_as_light", text="Multiple Importance")
col.prop(cmat, "use_transparent_shadow")
col = split.column()
col.label(text="Volume:")
col.prop(cmat, "volume_sampling", text="")
col.prop(cmat, "homogeneous_volume", text="Homogeneous")
class CyclesTexture_PT_context(CyclesButtonsPanel, Panel):
bl_label = ""

@ -977,6 +977,7 @@ void BlenderSync::sync_materials(bool update_all)
shader->use_mis = get_boolean(cmat, "sample_as_light");
shader->use_transparent_shadow = get_boolean(cmat, "use_transparent_shadow");
shader->heterogeneous_volume = !get_boolean(cmat, "homogeneous_volume");
shader->volume_sampling_method = RNA_enum_get(&cmat, "volume_sampling");
shader->set_graph(graph);
shader->tag_update(scene);
@ -1006,6 +1007,7 @@ void BlenderSync::sync_world(bool update_all)
/* volume */
PointerRNA cworld = RNA_pointer_get(&b_world.ptr, "cycles");
shader->heterogeneous_volume = !get_boolean(cworld, "homogeneous_volume");
shader->volume_sampling_method = RNA_enum_get(&cworld, "volume_sampling");
}
else if(b_world) {
ShaderNode *closure, *out;

@ -177,7 +177,6 @@ void BlenderSync::sync_integrator()
integrator->transparent_min_bounce = get_int(cscene, "transparent_min_bounces");
integrator->transparent_shadows = get_boolean(cscene, "use_transparent_shadows");
integrator->volume_homogeneous_sampling = RNA_enum_get(&cscene, "volume_homogeneous_sampling");
integrator->volume_max_steps = get_int(cscene, "volume_max_steps");
integrator->volume_step_size = get_float(cscene, "volume_step_size");

@ -89,7 +89,8 @@ ccl_device void kernel_path_indirect(KernelGlobals *kg, RNG *rng, Ray ray,
volume_ray.t = (hit)? isect.t: FLT_MAX;
bool heterogeneous = volume_stack_is_heterogeneous(kg, state.volume_stack);
bool decoupled = kernel_volume_use_decoupled(kg, heterogeneous, false);
int sampling_method = volume_stack_sampling_method(kg, state.volume_stack);
bool decoupled = kernel_volume_use_decoupled(kg, heterogeneous, false, sampling_method);
if(decoupled) {
/* cache steps along volume for repeated sampling */
@ -99,6 +100,8 @@ ccl_device void kernel_path_indirect(KernelGlobals *kg, RNG *rng, Ray ray,
shader_setup_from_volume(kg, &volume_sd, &volume_ray, state.bounce, state.transparent_bounce);
kernel_volume_decoupled_record(kg, &state,
&volume_ray, &volume_sd, &volume_segment, heterogeneous);
volume_segment.sampling_method = sampling_method;
/* emission */
if(volume_segment.closure_flag & SD_EMISSION)
@ -468,7 +471,8 @@ ccl_device float4 kernel_path_integrate(KernelGlobals *kg, RNG *rng, int sample,
volume_ray.t = (hit)? isect.t: FLT_MAX;
bool heterogeneous = volume_stack_is_heterogeneous(kg, state.volume_stack);
bool decoupled = kernel_volume_use_decoupled(kg, heterogeneous, true);
int sampling_method = volume_stack_sampling_method(kg, state.volume_stack);
bool decoupled = kernel_volume_use_decoupled(kg, heterogeneous, true, sampling_method);
if(decoupled) {
/* cache steps along volume for repeated sampling */
@ -479,6 +483,8 @@ ccl_device float4 kernel_path_integrate(KernelGlobals *kg, RNG *rng, int sample,
kernel_volume_decoupled_record(kg, &state,
&volume_ray, &volume_sd, &volume_segment, heterogeneous);
volume_segment.sampling_method = sampling_method;
/* emission */
if(volume_segment.closure_flag & SD_EMISSION)
path_radiance_accum_emission(&L, throughput, volume_segment.accum_emission, state.bounce);
@ -814,7 +820,10 @@ ccl_device float4 kernel_branched_path_integrate(KernelGlobals *kg, RNG *rng, in
/* direct light sampling */
if(volume_segment.closure_flag & SD_SCATTER) {
volume_segment.sampling_method = volume_stack_sampling_method(kg, state.volume_stack);
bool all = kernel_data.integrator.sample_all_lights_direct;
kernel_branched_path_volume_connect_light(kg, rng, &volume_sd,
throughput, &state, &L, 1.0f, all, &volume_ray, &volume_segment);

@ -577,7 +577,8 @@ enum ShaderDataFlag {
SD_AO = 512, /* have ao closure? */
SD_TRANSPARENT = 1024, /* have transparent closure? */
SD_CLOSURE_FLAGS = (SD_EMISSION|SD_BSDF|SD_BSDF_HAS_EVAL|SD_BSDF_GLOSSY|SD_BSSRDF|SD_HOLDOUT|SD_ABSORPTION|SD_SCATTER|SD_AO),
SD_CLOSURE_FLAGS = (SD_EMISSION|SD_BSDF|SD_BSDF_HAS_EVAL|SD_BSDF_GLOSSY|
SD_BSSRDF|SD_HOLDOUT|SD_ABSORPTION|SD_SCATTER|SD_AO),
/* shader flags */
SD_USE_MIS = 2048, /* direct light sample */
@ -586,13 +587,17 @@ enum ShaderDataFlag {
SD_HAS_ONLY_VOLUME = 16384, /* has only volume shader, no surface */
SD_HETEROGENEOUS_VOLUME = 32768, /* has heterogeneous volume */
SD_HAS_BSSRDF_BUMP = 65536, /* bssrdf normal uses bump */
SD_VOLUME_EQUIANGULAR = 131072, /* use equiangular sampling */
SD_VOLUME_MIS = 262144, /* use multiple importance sampling */
SD_SHADER_FLAGS = (SD_USE_MIS|SD_HAS_TRANSPARENT_SHADOW|SD_HAS_VOLUME|SD_HAS_ONLY_VOLUME|SD_HETEROGENEOUS_VOLUME|SD_HAS_BSSRDF_BUMP),
SD_SHADER_FLAGS = (SD_USE_MIS|SD_HAS_TRANSPARENT_SHADOW|SD_HAS_VOLUME|
SD_HAS_ONLY_VOLUME|SD_HETEROGENEOUS_VOLUME|
SD_HAS_BSSRDF_BUMP|SD_VOLUME_EQUIANGULAR|SD_VOLUME_MIS),
/* object flags */
SD_HOLDOUT_MASK = 131072, /* holdout for camera rays */
SD_OBJECT_MOTION = 262144, /* has object motion blur */
SD_TRANSFORM_APPLIED = 524288, /* vertices have transform applied */
SD_HOLDOUT_MASK = 524288, /* holdout for camera rays */
SD_OBJECT_MOTION = 1048576, /* has object motion blur */
SD_TRANSFORM_APPLIED = 2097152, /* vertices have transform applied */
SD_OBJECT_FLAGS = (SD_HOLDOUT_MASK|SD_OBJECT_MOTION|SD_TRANSFORM_APPLIED)
};
@ -894,7 +899,6 @@ typedef struct KernelIntegrator {
int aa_samples;
/* volume render */
int volume_homogeneous_sampling;
int use_volumes;
int volume_max_steps;
float volume_step_size;

@ -116,6 +116,36 @@ ccl_device bool volume_stack_is_heterogeneous(KernelGlobals *kg, VolumeStack *st
return false;
}
ccl_device int volume_stack_sampling_method(KernelGlobals *kg, VolumeStack *stack)
{
if(kernel_data.integrator.num_all_lights == 0)
return 0;
int method = -1;
for(int i = 0; stack[i].shader != SHADER_NONE; i++) {
int shader_flag = kernel_tex_fetch(__shader_flag, (stack[i].shader & SHADER_MASK)*2);
if(shader_flag & SD_VOLUME_MIS) {
return SD_VOLUME_MIS;
}
else if(shader_flag & SD_VOLUME_EQUIANGULAR) {
if(method == 0)
return SD_VOLUME_MIS;
method = SD_VOLUME_EQUIANGULAR;
}
else {
if(method == SD_VOLUME_EQUIANGULAR)
return SD_VOLUME_MIS;
method = 0;
}
}
return method;
}
/* Volume Shadows
*
* These functions are used to attenuate shadow rays to lights. Both absorption
@ -562,6 +592,8 @@ typedef struct VolumeSegment {
float3 accum_emission; /* accumulated emission at end of segment */
float3 accum_transmittance; /* accumulated transmittance at end of segment */
int sampling_method; /* volume sampling method */
} VolumeSegment;
/* record volume steps to the end of the volume.
@ -709,6 +741,8 @@ ccl_device VolumeIntegrateResult kernel_volume_decoupled_scatter(
{
int closure_flag = segment->closure_flag;
/* XXX add probalistic scattering! */
if(!(closure_flag & SD_SCATTER))
return VOLUME_PATH_MISSED;
@ -737,8 +771,8 @@ ccl_device VolumeIntegrateResult kernel_volume_decoupled_scatter(
bool distance_sample = true;
bool use_mis = false;
if(kernel_data.integrator.volume_homogeneous_sampling && light_P) {
if(kernel_data.integrator.volume_homogeneous_sampling == 2) {
if(segment->sampling_method && light_P) {
if(segment->sampling_method == SD_VOLUME_MIS) {
/* multiple importance sample: randomly pick between
* equiangular and distance sampling strategy */
if(xi < 0.5f) {
@ -872,7 +906,7 @@ ccl_device VolumeIntegrateResult kernel_volume_decoupled_scatter(
}
/* decide if we need to use decoupled or not */
ccl_device bool kernel_volume_use_decoupled(KernelGlobals *kg, bool heterogeneous, bool direct)
ccl_device bool kernel_volume_use_decoupled(KernelGlobals *kg, bool heterogeneous, bool direct, int sampling_method)
{
/* decoupled ray marching for heterogenous volumes not supported on the GPU,
* which also means equiangular and multiple importance sampling is not
@ -882,9 +916,8 @@ ccl_device bool kernel_volume_use_decoupled(KernelGlobals *kg, bool heterogeneou
return false;
#endif
/* equiangular sampling only implemented for decoupled */
bool equiangular = kernel_data.integrator.volume_homogeneous_sampling != 0;
if(equiangular)
/* equiangular and multiple importance sampling only implemented for decoupled */
if(sampling_method != 0)
return true;
/* for all light sampling use decoupled, reusing shader evaluations is

@ -101,11 +101,6 @@ void Integrator::device_update(Device *device, DeviceScene *dscene, Scene *scene
if(!transparent_shadows)
kintegrator->transparent_shadows = false;
if(kintegrator->num_all_lights > 0)
kintegrator->volume_homogeneous_sampling = volume_homogeneous_sampling;
else
kintegrator->volume_homogeneous_sampling = 0;
kintegrator->volume_max_steps = volume_max_steps;
kintegrator->volume_step_size = volume_step_size;

@ -44,6 +44,7 @@ Shader::Shader()
use_mis = true;
use_transparent_shadow = true;
heterogeneous_volume = true;
volume_sampling_method = 0;
has_surface = false;
has_surface_transparent = false;
@ -257,6 +258,10 @@ void ShaderManager::device_update_common(Device *device, DeviceScene *dscene, Sc
flag |= SD_HAS_BSSRDF_BUMP;
if(shader->has_converter_blackbody)
has_converter_blackbody = true;
if(shader->volume_sampling_method == 1)
flag |= SD_VOLUME_EQUIANGULAR;
if(shader->volume_sampling_method == 2)
flag |= SD_VOLUME_MIS;
/* regular shader */
shader_flag[i++] = flag;

@ -68,6 +68,7 @@ public:
bool use_mis;
bool use_transparent_shadow;
bool heterogeneous_volume;
int volume_sampling_method;
/* synchronization */
bool need_update;