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Commit c38abe1a authored by Christian Schulte zu Berge's avatar Christian Schulte zu Berge
Browse files

Extracted adaptive step size and empty space skipping from SimpleRaycaster to OptimizedRaycaster

parent b019d377
// ================================================================================================
//
// This file is part of the CAMPVis Software Framework.
//
// If not explicitly stated otherwise: Copyright (C) 2012, all rights reserved,
// Christian Schulte zu Berge <christian.szb@in.tum.de>
// Chair for Computer Aided Medical Procedures
// Technische Universitt Mnchen
// Boltzmannstr. 3, 85748 Garching b. Mnchen, Germany
// For a full list of authors and contributors, please refer to the file "AUTHORS.txt".
//
// The licensing of this softare is not yet resolved. Until then, redistribution in source or
// binary forms outside the CAMP chair is not permitted, unless explicitly stated in legal form.
// However, the names of the original authors and the above copyright notice must retain in its
// original state in any case.
//
// Legal disclaimer provided by the BSD license:
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
// OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
// ================================================================================================
layout(location = 0) out vec4 out_Color; ///< outgoing fragment color
layout(location = 1) out vec4 out_FHP; ///< outgoing fragment first hitpoint
layout(location = 2) out vec4 out_FHN; ///< outgoing fragment first hit normal
#include "tools/gradient.frag"
#include "tools/raycasting.frag"
#include "tools/shading.frag"
#include "tools/texture2d.frag"
#include "tools/texture3d.frag"
#include "tools/transferfunction.frag"
uniform vec2 _viewportSizeRCP;
uniform float _jitterStepSizeMultiplier;
// ray entry points
uniform sampler2D _entryPoints;
uniform sampler2D _entryPointsDepth;
uniform TextureParameters2D _entryParams;
// ray exit points
uniform sampler2D _exitPoints;
uniform sampler2D _exitPointsDepth;
uniform TextureParameters2D _exitParams;
// DRR volume
uniform sampler3D _volume;
uniform TextureParameters3D _volumeTextureParams;
// Transfer function
uniform sampler1D _transferFunction;
uniform TFParameters1D _transferFunctionParams;
// BBV Lookup volume
uniform usampler3D _bbvTexture;
uniform TextureParameters3D _bbvTextureParams;
uniform int _bbvBrickSize;
uniform bool _hasBbv;
uniform LightSource _lightSource;
uniform vec3 _cameraPosition;
uniform float _samplingStepSize;
#ifdef ENABLE_ADAPTIVE_STEPSIZE
bool _inVoid = false;
#endif
#ifdef ENABLE_SHADOWING
uniform float _shadowIntensity;
#endif
const float positiveInfinity = 1.0 / 0.0;
// TODO: copy+paste from Voreen - eliminate or improve.
const float SAMPLING_BASE_INTERVAL_RCP = 200.0;
ivec3 voxelToBrick(in vec3 voxel) {
return ivec3(floor(voxel / _bbvBrickSize));
}
// samplePosition is in texture coordiantes [0, 1]
bool lookupInBbv(in vec3 samplePosition) {
ivec3 byte = voxelToBrick(samplePosition * _volumeTextureParams._size);
uint bit = uint(byte.x % 8);
byte.x /= 8;
uint texel = texelFetch(_bbvTexture, byte, 0).r;
return (texel & (1U << bit)) != 0U;
}
float rayBoxIntersection(in vec3 rayOrigin, in vec3 rayDirection, in vec3 box[2], in float t) {
vec3 rayInverseDirection = 1.f / rayDirection;
ivec3 raySign = ivec3(lessThan(rayDirection, vec3(0.0, 0.0, 0.0));
vec3 tMin = (box[raySign] - rayOrigin) / rayInverseDirection;
vec3 tMax = (box[1 - raySign] - rayOrigin) / rayInverseDirection;
tMin *= vec3(lessThan(tMin, vec3(t, t, t)) * positiveInfinity;
tMax *= vec3(lessThan(tMax, vec3(t, t, t)) * positiveInfinity;
return min(min(tMin.x, min(tMin.y, tMin.z)) , min(tMax.x, min(tMax.y, tMax.z)));
}
/**
* Performs the raycasting and returns the final fragment color.
*/
vec4 performRaycasting(in vec3 entryPoint, in vec3 exitPoint, in vec2 texCoords) {
vec4 result = vec4(0.0);
float firstHitT = -1.0;
#ifdef ENABLE_ADAPTIVE_STEPSIZE
float samplingRateCompensationMultiplier = 1.0;
#endif
// calculate ray parameters
vec3 direction = exitPoint.rgb - entryPoint.rgb;
float t = 0.0;
float tend = length(direction);
direction = normalize(direction);
jitterEntryPoint(entryPoint, direction, _samplingStepSize * _jitterStepSizeMultiplier);
while (t < tend) {
// compute sample position
vec3 samplePosition = entryPoint.rgb + t * direction;
if (_hasBbv) {
if (! lookupInBbv(samplePosition)) {
// advance to the next evaluation point along the ray
t += 4.0*_samplingStepSize;
#ifdef ENABLE_ADAPTIVE_STEPSIZE
samplingRateCompensationMultiplier = 1.0;
#endif
continue;
}
}
// lookup intensity and TF
float intensity = getElement3DNormalized(_volume, _volumeTextureParams, samplePosition).a;
vec4 color = lookupTF(_transferFunction, _transferFunctionParams, intensity);
#ifdef ENABLE_ADAPTIVE_STEPSIZE
if (color.a <= 0.0) {
// we're within void, make the steps bigger
_inVoid = true;
}
else {
if (_inVoid) {
float formerT = t - _samplingStepSize;
// we just left the void, perform intersection refinement
for (float stepPower = 0.5; stepPower > 0.1; stepPower /= 2.0) {
// compute refined sample position
float newT = formerT + _samplingStepSize * stepPower;
vec3 newSamplePosition = entryPoint.rgb + newT * direction;
// lookup refined intensity + TF
float newIntensity = getElement3DNormalized(_volume, _volumeTextureParams, newSamplePosition).a;
vec4 newColor = lookupTF(_transferFunction, _transferFunctionParams, newIntensity);
if (newColor.a <= 0.0) {
// we're back in the void - look on the right-hand side
formerT = newT;
}
else {
// we're still in the matter - look on the left-hand side
samplePosition = newSamplePosition;
color = newColor;
t -= _samplingStepSize * stepPower;
}
}
_inVoid = false;
}
}
#endif
#ifdef ENABLE_SHADOWING
// simple and expensive implementation of hard shadows
if (color.a > 0.1) {
// compute direction from sample to light
vec3 L = normalize(_lightSource._position - textureToWorld(_volumeTextureParams, samplePosition).xyz) * _samplingStepSize;
bool finished = false;
vec3 position = samplePosition + L;
float shadowFactor = 0.0;
// traverse ray from sample to light
while (! finished) {
// grab intensity and TF opacity
intensity = getElement3DNormalized(_volume, _volumeTextureParams, position).a;
shadowFactor += lookupTF(_transferFunction, _transferFunctionParams, intensity).a;
position += L;
finished = (shadowFactor > 0.95)
|| any(lessThan(position, vec3(0.0, 0.0, 0.0)))
|| any(greaterThan(position, vec3(1.0, 1.0, 1.0)));
}
// apply shadow to color
color.rgb *= (1.0 - shadowFactor * _shadowIntensity);
}
#endif
// perform compositing
if (color.a > 0.0) {
#ifdef ENABLE_SHADING
// compute gradient (needed for shading and normals)
vec3 gradient = computeGradient(_volume, _volumeTextureParams, samplePosition);
color.rgb = calculatePhongShading(textureToWorld(_volumeTextureParams, samplePosition).xyz, _lightSource, _cameraPosition, gradient, color.rgb, color.rgb, vec3(1.0, 1.0, 1.0));
#endif
// accomodate for variable sampling rates
#ifdef ENABLE_ADAPTIVE_STEPSIZE
color.a = 1.0 - pow(1.0 - color.a, _samplingStepSize * samplingRateCompensationMultiplier * SAMPLING_BASE_INTERVAL_RCP);
#else
color.a = 1.0 - pow(1.0 - color.a, _samplingStepSize * SAMPLING_BASE_INTERVAL_RCP);
#endif
result.rgb = mix(color.rgb, result.rgb, result.a);
result.a = result.a + (1.0 -result.a) * color.a;
}
// save first hit ray parameter for depth value calculation
if (firstHitT < 0.0 && result.a > 0.0) {
firstHitT = t;
out_FHP = vec4(samplePosition, 1.0);
out_FHN = vec4(normalize(computeGradient(_volume, _volumeTextureParams, samplePosition)), 1.0);
}
// early ray termination
if (result.a > 0.975) {
result.a = 1.0;
t = tend;
}
// advance to the next evaluation point along the ray
#ifdef ENABLE_ADAPTIVE_STEPSIZE
samplingRateCompensationMultiplier = (_inVoid ? 1.0 : 0.25);
t += _samplingStepSize * (_inVoid ? 1.0 : 0.125);
#else
t += _samplingStepSize;
#endif
}
// calculate depth value from ray parameter
gl_FragDepth = 1.0;
if (firstHitT >= 0.0) {
float depthEntry = getElement2DNormalized(_entryPointsDepth, _entryParams, texCoords).z;
float depthExit = getElement2DNormalized(_exitPointsDepth, _exitParams, texCoords).z;
gl_FragDepth = calculateDepthValue(firstHitT/tend, depthEntry, depthExit);
}
return result;
}
/***
* The main method.
***/
void main() {
vec2 p = gl_FragCoord.xy * _viewportSizeRCP;
vec3 frontPos = getElement2DNormalized(_entryPoints, _entryParams, p).rgb;
vec3 backPos = getElement2DNormalized(_exitPoints, _exitParams, p).rgb;
//determine whether the ray has to be casted
if (frontPos == backPos) {
//background need no raycasting
discard;
} else {
//fragCoords are lying inside the boundingbox
out_Color = performRaycasting(frontPos, backPos, p);
}
}
......@@ -61,22 +61,11 @@ uniform sampler1D _transferFunction;
uniform TFParameters1D _transferFunctionParams;
// BBV Lookup volume
uniform usampler3D _bbvTexture;
uniform TextureParameters3D _bbvTextureParams;
uniform int _bbvBrickSize;
uniform bool _hasBbv;
uniform LightSource _lightSource;
uniform vec3 _cameraPosition;
uniform float _samplingStepSize;
#ifdef ENABLE_ADAPTIVE_STEPSIZE
bool _inVoid = false;
#endif
#ifdef ENABLE_SHADOWING
uniform float _shadowIntensity;
#endif
......@@ -84,30 +73,12 @@ uniform float _shadowIntensity;
// TODO: copy+paste from Voreen - eliminate or improve.
const float SAMPLING_BASE_INTERVAL_RCP = 200.0;
ivec3 voxelToBrick(in vec3 voxel) {
return ivec3(floor(voxel / _bbvBrickSize));
}
// samplePosition is in texture coordiantes [0, 1]
bool lookupInBbv(in vec3 samplePosition) {
ivec3 byte = voxelToBrick(samplePosition * _volumeTextureParams._size);
uint bit = uint(byte.x % 8);
byte.x /= 8;
uint texel = texelFetch(_bbvTexture, byte, 0).r;
return (texel & (1U << bit)) != 0U;
}
/**
* Performs the raycasting and returns the final fragment color.
*/
vec4 performRaycasting(in vec3 entryPoint, in vec3 exitPoint, in vec2 texCoords) {
vec4 result = vec4(0.0);
float firstHitT = -1.0;
#ifdef ENABLE_ADAPTIVE_STEPSIZE
float samplingRateCompensationMultiplier = 1.0;
#endif
// calculate ray parameters
vec3 direction = exitPoint.rgb - entryPoint.rgb;
......@@ -121,59 +92,10 @@ vec4 performRaycasting(in vec3 entryPoint, in vec3 exitPoint, in vec2 texCoords)
// compute sample position
vec3 samplePosition = entryPoint.rgb + t * direction;
if (_hasBbv) {
if (! lookupInBbv(samplePosition)) {
// advance to the next evaluation point along the ray
t += 4.0*_samplingStepSize;
#ifdef ENABLE_ADAPTIVE_STEPSIZE
samplingRateCompensationMultiplier = 1.0;
#endif
continue;
}
}
// lookup intensity and TF
float intensity = getElement3DNormalized(_volume, _volumeTextureParams, samplePosition).a;
vec4 color = lookupTF(_transferFunction, _transferFunctionParams, intensity);
#ifdef ENABLE_ADAPTIVE_STEPSIZE
if (color.a <= 0.0) {
// we're within void, make the steps bigger
_inVoid = true;
}
else {
if (_inVoid) {
float formerT = t - _samplingStepSize;
// we just left the void, perform intersection refinement
for (float stepPower = 0.5; stepPower > 0.1; stepPower /= 2.0) {
// compute refined sample position
float newT = formerT + _samplingStepSize * stepPower;
vec3 newSamplePosition = entryPoint.rgb + newT * direction;
// lookup refined intensity + TF
float newIntensity = getElement3DNormalized(_volume, _volumeTextureParams, newSamplePosition).a;
vec4 newColor = lookupTF(_transferFunction, _transferFunctionParams, newIntensity);
if (newColor.a <= 0.0) {
// we're back in the void - look on the right-hand side
formerT = newT;
}
else {
// we're still in the matter - look on the left-hand side
samplePosition = newSamplePosition;
color = newColor;
t -= _samplingStepSize * stepPower;
}
}
_inVoid = false;
}
}
#endif
#ifdef ENABLE_SHADOWING
// simple and expensive implementation of hard shadows
if (color.a > 0.1) {
......@@ -209,11 +131,7 @@ vec4 performRaycasting(in vec3 entryPoint, in vec3 exitPoint, in vec2 texCoords)
#endif
// accomodate for variable sampling rates
#ifdef ENABLE_ADAPTIVE_STEPSIZE
color.a = 1.0 - pow(1.0 - color.a, _samplingStepSize * samplingRateCompensationMultiplier * SAMPLING_BASE_INTERVAL_RCP);
#else
color.a = 1.0 - pow(1.0 - color.a, _samplingStepSize * SAMPLING_BASE_INTERVAL_RCP);
#endif
result.rgb = mix(color.rgb, result.rgb, result.a);
result.a = result.a + (1.0 -result.a) * color.a;
}
......@@ -232,13 +150,7 @@ vec4 performRaycasting(in vec3 entryPoint, in vec3 exitPoint, in vec2 texCoords)
}
// advance to the next evaluation point along the ray
#ifdef ENABLE_ADAPTIVE_STEPSIZE
samplingRateCompensationMultiplier = (_inVoid ? 1.0 : 0.25);
t += _samplingStepSize * (_inVoid ? 1.0 : 0.125);
#else
t += _samplingStepSize;
#endif
}
// calculate depth value from ray parameter
......
// ================================================================================================
//
// This file is part of the CAMPVis Software Framework.
//
// If not explicitly stated otherwise: Copyright (C) 2012, all rights reserved,
// Christian Schulte zu Berge <christian.szb@in.tum.de>
// Chair for Computer Aided Medical Procedures
// Technische Universität München
// Boltzmannstr. 3, 85748 Garching b. München, Germany
// For a full list of authors and contributors, please refer to the file "AUTHORS.txt".
//
// The licensing of this softare is not yet resolved. Until then, redistribution in source or
// binary forms outside the CAMP chair is not permitted, unless explicitly stated in legal form.
// However, the names of the original authors and the above copyright notice must retain in its
// original state in any case.
//
// Legal disclaimer provided by the BSD license:
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
// OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
// ================================================================================================
#include "optimizedraycaster.h"
#include "core/tools/quadrenderer.h"
#include "core/datastructures/renderdata.h"
#include "core/pipeline/processordecoratorshading.h"
#include <tbb/tbb.h>
namespace campvis {
const std::string OptimizedRaycaster::loggerCat_ = "CAMPVis.modules.vis.OptimizedRaycaster";
OptimizedRaycaster::OptimizedRaycaster(IVec2Property* viewportSizeProp)
: RaycastingProcessor(viewportSizeProp, "modules/vis/glsl/optimizedraycaster.frag", true)
, p_targetImageID("targetImageID", "Output Image", "", DataNameProperty::WRITE)
, p_enableShadowing("EnableShadowing", "Enable Hard Shadows (Expensive!)", false, AbstractProcessor::INVALID_RESULT | AbstractProcessor::INVALID_SHADER | AbstractProcessor::INVALID_PROPERTIES)
, p_shadowIntensity("ShadowIntensity", "Shadow Intensity", .5f, .0f, 1.f)
, p_enableAdaptiveStepsize("EnableAdaptiveStepSize", "Enable Adaptive Step Size", true, AbstractProcessor::INVALID_RESULT | AbstractProcessor::INVALID_SHADER)
, p_useEmptySpaceSkipping("EnableEmptySpaceSkipping", "Enable Empty Space Skipping", false, AbstractProcessor::INVALID_RESULT | INVALID_BBV)
, _bbv(0)
, _t(0)
{
addDecorator(new ProcessorDecoratorShading());
addProperty(&p_targetImageID);
addProperty(&p_enableAdaptiveStepsize);
addProperty(&p_useEmptySpaceSkipping);
addProperty(&p_enableShadowing);
addProperty(&p_shadowIntensity);
p_shadowIntensity.setVisible(false);
// p_transferFunction.setInvalidationLevel(p_transferFunction.getInvalidationLevel() | INVALID_BBV);
// p_sourceImageID.setInvalidationLevel(p_sourceImageID.getInvalidationLevel() | INVALID_BBV);
decoratePropertyCollection(this);
}
OptimizedRaycaster::~OptimizedRaycaster() {
}
void OptimizedRaycaster::init() {
RaycastingProcessor::init();
}
void OptimizedRaycaster::deinit() {
delete _bbv;
delete _t;
RaycastingProcessor::deinit();
}
void OptimizedRaycaster::processImpl(DataContainer& data, ImageRepresentationGL::ScopedRepresentation& image) {
tgt::TextureUnit bbvUnit;
if (getInvalidationLevel() & INVALID_BBV) {
DataHandle dh = DataHandle(const_cast<ImageData*>(image->getParent())); // HACK HACK HACK
generateBbv(dh);
// tgt::Texture* batman = _bbv->exportToImageData();
// ImageData* robin = new ImageData(3, batman->getDimensions(), 1);
// ImageRepresentationGL::create(robin, batman);
// data.addData("All glory to the HYPNOTOAD!", robin);
validate(INVALID_BBV);
}
if (_t != 0 && p_useEmptySpaceSkipping.getValue()) {
// bind
bbvUnit.activate();
_t->bind();
_shader->setIgnoreUniformLocationError(true);
_shader->setUniform("_bbvTexture", bbvUnit.getUnitNumber());
_shader->setUniform("_bbvTextureParams._size", tgt::vec3(_t->getDimensions()));
_shader->setUniform("_bbvTextureParams._sizeRCP", tgt::vec3(1.f) / tgt::vec3(_t->getDimensions()));
_shader->setUniform("_bbvTextureParams._numChannels", static_cast<int>(1));
_shader->setUniform("_bbvBrickSize", static_cast<int>(_bbv->getBrickSize()));
_shader->setUniform("_hasBbv", true);
_shader->setIgnoreUniformLocationError(false);
}
else {
_shader->setUniform("_hasBbv", false);
}
FramebufferActivationGuard fag(this);
createAndAttachTexture(GL_RGBA8);
// createAndAttachTexture(GL_RGBA32F);
// createAndAttachTexture(GL_RGBA32F);
createAndAttachDepthTexture();
// static const GLenum buffers[] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1 , GL_COLOR_ATTACHMENT2 };
// glDrawBuffers(3, buffers);
if (p_enableShadowing.getValue())
_shader->setUniform("_shadowIntensity", p_shadowIntensity.getValue());
glEnable(GL_DEPTH_TEST);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
QuadRdr.renderQuad();
glDisable(GL_DEPTH_TEST);
LGL_ERROR;
data.addData(p_targetImageID.getValue(), new RenderData(_fbo));
}
std::string OptimizedRaycaster::generateHeader() const {
std::string toReturn = RaycastingProcessor::generateHeader();
if (p_enableShadowing.getValue())
toReturn += "#define ENABLE_SHADOWING\n";
if (p_enableAdaptiveStepsize.getValue())
toReturn += "#define ENABLE_ADAPTIVE_STEPSIZE\n";
return toReturn;
}
void OptimizedRaycaster::updateProperties() {
p_shadowIntensity.setVisible(p_enableShadowing.getValue());
validate(AbstractProcessor::INVALID_PROPERTIES);
}
void OptimizedRaycaster::generateBbv(DataHandle dh) {
delete _bbv;
_bbv = 0;
delete _t;
_t = 0;
if (dh.getData() == 0) {
return;
}
else {
if (const ImageData* id = dynamic_cast<const ImageData*>(dh.getData())) {
if (const ImageRepresentationLocal* rep = id->getRepresentation<ImageRepresentationLocal>(true)) {
_bbv = new BinaryBrickedVolume(rep->getParent(), 2);
GLubyte* tfBuffer = p_transferFunction.getTF()->getTexture()->downloadTextureToBuffer(GL_RGBA, GL_UNSIGNED_BYTE);
size_t tfNumElements = p_transferFunction.getTF()->getTexture()->getDimensions().x;
LDEBUG("Start computing brick visibilities...");
// parallelly traverse the bricks
// have minimum group size 8 to avoid race conditions (every 8 neighbor bricks write to the same byte)!
tbb::parallel_for(tbb::blocked_range<size_t>(0, _bbv->getNumBrickIndices(), 8), [&] (const tbb::blocked_range<size_t>& range) {
const tgt::vec2& tfIntensityDomain = p_transferFunction.getTF()->getIntensityDomain();
for (size_t i = range.begin(); i != range.end(); ++i) {
// for each brick, get all corresponding voxels in the reference volume
std::vector<tgt::svec3> voxels = _bbv->getAllVoxelsForBrick(i);
// traverse the voxels to check whether their intensities are mapped to some opacity
for (size_t v = 0; v < voxels.size(); ++v) {
// apply same TF lookup as in shader...