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WIP: throughput sampling (feed throughput)
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enigmahe committed Jun 25, 2024
1 parent 44cfed2 commit 6ac936f
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Showing 3 changed files with 68 additions and 31 deletions.
91 changes: 63 additions & 28 deletions bxdf/volume.py
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Original file line number Diff line number Diff line change
Expand Up @@ -71,7 +71,7 @@ def __init__(self, elem: xet.Element):
"float": lambda el: get(el, "value"),
"string": lambda el: self.setup_volume(get(el, "path", str)),
"transform": lambda el: self.assign_transform(*transform_parse(el)),
"bool": lambda el: get(el, "value", bool)
"bool": lambda el: el.get("value") in {"True", "true"}
}
if elem is not None:
type_name = elem.get("type")
Expand Down Expand Up @@ -102,9 +102,10 @@ def __init__(self, elem: xet.Element):
else:
CONSOLE.log("Mono-chromatic volume is converted to RGB volume.")
self.channel = 3
self.type_id = GridVolume_np.RGB
self.density_grid = GridVolume_np.make_colorful_volume(self.density_grid, self.xres, self.yres, self.zres)
else:
self.density_grid = np.concatenate([self.density_grid] * 3, axis = -1)
self.density_grid = np.concatenate([self.density_grid, self.density_grid, self.density_grid], axis = -1)

if self.scale is None:
self.scale = np.eye(3, dtype = np.float32)
Expand All @@ -113,8 +114,10 @@ def __init__(self, elem: xet.Element):
self.forward_t = self.rotation @ self.scale
if self.type_id == GridVolume_np.MONO:
self.density_grid *= self.density_scaling[0]
CONSOLE.log(f"Volume density scaled by {self.density_scaling[0]}.")
else:
self.density_grid *= self.density_scaling
CONSOLE.log(f"Volume density scaled by {self.density_scaling}.")

def assign_transform(self, trans_r, trans_t, trans_s):
self.rotation = trans_r
Expand All @@ -138,9 +141,9 @@ def make_colorful_volume(density_grid: np.ndarray, xres: int, yres: int, zres: i
y_coords = np.linspace(0, 0.9, yres, dtype = np.float32).reshape(1, -1, 1, 1) + 0.1
x_coords = np.linspace(0, 0.9, xres, dtype = np.float32).reshape(1, 1, -1, 1) + 0.1
density_grid = np.concatenate([
density_grid * z_coords,
density_grid * y_coords,
density_grid * x_coords
density_grid,
density_grid,
density_grid,
], axis = -1)
return density_grid

Expand Down Expand Up @@ -308,73 +311,105 @@ def sample_distance_delta_tracking_3d(self, grid: ti.template(), ray_ol: vec3, r
result = vec4([1, 1, 1, -1])
if self._type:
# Step 1: choose one element according to the majorant
Tr = 1.0
pdf = 1.0
albedo = 0.0
channel = 0
maj = 1.0
maj = self.majorant[2]
val = ti.random(float)
if val < self.pdf[0]:
albedo = self.albedo[0]
maj = self.majorant[0]
pdf = self.pdf[0]
channel = 0
elif val < self.pdf[0] + self.pdf[1]:
albedo = self.albedo[1]
maj = self.majorant[1]
pdf = self.pdf[1]
channel = 1
else:
channel = 2
albedo = self.albedo[2]
maj = self.majorant[2]
pdf = self.pdf[2]
channel = 2
inv_maj = 1.0 / maj

t = near_far[0]
dist = -ti.log(1.0 - ti.random(float)) * inv_maj
while t + dist < near_far[1]:
t += dist

t = near_far[0] - ti.log(1.0 - ti.random(float)) * inv_maj
while t < near_far[1]:
d = self.density_lookup_3d(grid, ray_ol + t * ray_dl, vec3([
ti.random(float), ti.random(float), ti.random(float)
]))

# Scatter upon real collision
n_s = rgb_select(d, channel)
if ti.random(float) < n_s * inv_maj:
result[:3] *= self.albedo
Tr *= albedo
result[3] = t
break
dist = -ti.log(1.0 - ti.random(float)) * inv_maj
if t + dist >= near_far[1]:
dist = near_far[1] - t

t -= ti.log(1.0 - ti.random(float)) * inv_maj
if self._type == GridVolume_np.RGB:
if channel == 0:
result[:3] = vec3([Tr / pdf, 0, 0])
elif channel == 1:
result[:3] = vec3([0, Tr / pdf, 0])
else:
result[:3] = vec3([0, 0, Tr / pdf])
else:
result[:3] = vec3([Tr, Tr, Tr])
return result

@ti.func
def eval_tr_ratio_tracking_3d(self, grid: ti.template(), ray_ol: vec3, ray_dl: vec3, near_far: vec2) -> vec3:
Tr = ONES_V3
transm = ONES_V3
if self._type:
# Step 1: choose one element according to the majorant
maj = 1.0
Tr = 1.0
pdf = 1.0
channel = 0
maj = self.majorant[2]
val = ti.random(float)
if val < self.pdf[0]:
maj = self.majorant[0]
pdf = self.pdf[0]
channel = 0
elif val < self.pdf[0] + self.pdf[1]:
maj = self.majorant[1]
pdf = self.pdf[1]
channel = 1
else:
maj = self.majorant[2]
pdf = self.pdf[2]
channel = 2
inv_maj = 1.0 / maj

t = near_far[0]
while True:
dist = -ti.log(1.0 - ti.random(float)) * inv_maj
t -= ti.log(1.0 - ti.random(float)) * inv_maj

if t + dist >= near_far[1]: break
t += dist
if t >= near_far[1]: break
# for mono-chromatic medium, this is 1
d = self.density_lookup_3d(grid, ray_ol + t * ray_dl, vec3([
ti.random(float), ti.random(float), ti.random(float)
]))

Tr *= ti.max(ZERO_V3, 1.0 - d * inv_maj)
n_s = rgb_select(d, channel)
Tr *= ti.max(0.0, 1.0 - n_s * inv_maj)

# Russian Roulette
if Tr.max() < 0.1:
rr_max_val = Tr.max()
if ti.random(float) >= rr_max_val:
Tr.fill(0)
if Tr < 0.1:
if ti.random(float) >= Tr:
Tr = 0.0
break
Tr /= rr_max_val
return Tr
Tr = 1.0
if self._type == GridVolume_np.RGB:
if channel == 0:
transm = vec3([Tr / pdf, 0, 0])
elif channel == 1:
transm = vec3([0, Tr / pdf, 0])
else:
transm = vec3([0, 0, Tr / pdf])
else:
transm = vec3([Tr, Tr, Tr])
return transm

6 changes: 3 additions & 3 deletions scenes/cbox/cbox-rgbvol.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -68,7 +68,7 @@

<emitter type="area" id="area">
<rgb name="emission" value="50.0, 50.0, 50.0"/>
<rgb name="scaler" value="0.1"/>
<rgb name="scaler" value="0.3"/>
</emitter>

<shape type="obj">
Expand Down Expand Up @@ -110,10 +110,10 @@
</shape>

<!-- Definition of grid volume -->
<volume name="janga" type="rgb" phase_type="hg">
<volume name="janga" type="mono" phase_type="hg">
<string name="density_grid" path="./scenes/volume/janga-smoke-264-136-136.vol"/>
<rgb name="albedo" value="#F8F8F8"/>
<rgb name="density_scaling" value="20.0"/>
<rgb name="density_scaling" value="10.0"/>
<rgb name="par" value="0.7"/>
<bool name="mono2rgb" value="true"/>

Expand Down
2 changes: 2 additions & 0 deletions scenes/cbox/cbox-volgrid.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -148,6 +148,7 @@
<rgb name="albedo" value="#F8F8F8"/>
<rgb name="density_scaling" value="10.0"/>
<rgb name="par" value="0.7"/>
<bool name="mono2rgb" value="false"/>
<transform name="toWorld">
<translate x="0.5" y="-0.6" z="2.4"/>
Expand All @@ -161,6 +162,7 @@
<rgb name="albedo" value="#F8F8F8"/>
<rgb name="density_scaling" value="20.0"/>
<rgb name="par" value="0.7"/>
<bool name="mono2rgb" value="true"/>

<transform name="toWorld">
<translate x="0.6" y="0.0" z="1.3"/>
Expand Down

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