212 lines
6.6 KiB
C++
212 lines
6.6 KiB
C++
/*
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This file is part of Mitsuba, a physically based rendering system.
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Copyright (c) 2007-2014 by Wenzel Jakob and others.
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Mitsuba is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License Version 3
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as published by the Free Software Foundation.
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Mitsuba is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <mitsuba/core/statistics.h>
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#include <mitsuba/bidir/mut_lens.h>
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MTS_NAMESPACE_BEGIN
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static StatsCounter statsAccepted("Lens perturbation",
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"Acceptance rate", EPercentage);
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static StatsCounter statsGenerated("Lens perturbation",
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"Successful generation rate", EPercentage);
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LensPerturbation::LensPerturbation(const Scene *scene, Sampler *sampler,
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MemoryPool &pool, Float minJump, Float coveredArea) :
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m_scene(scene), m_sampler(sampler), m_pool(pool) {
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if (!scene->getSensor()->getClass()->derivesFrom(MTS_CLASS(PerspectiveCamera)))
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Log(EError, "The lens perturbation requires a perspective camera.");
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/* Reminder: the jump offset density is given by
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f(r) = 1/(r * log(r2/r1)) on [r1, r2]
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The expected value is: (r2-r1)/log(r2/r1)
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The inverse CDF is given by
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F^{-1}(U) = r2 * exp(-log(r2/r1) * (1-U))
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*/
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Vector2i sizeInPixels = scene->getFilm()->getCropSize();
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m_filmRes = Vector2((Float) sizeInPixels.x, (Float) sizeInPixels.y);
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m_imagePlaneArea = m_filmRes.x * m_filmRes.y;
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/* Pixel jump range (in pixels) [Veach, p.354] */
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m_r1 = minJump;
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m_r2 = std::sqrt(coveredArea * m_filmRes.x * m_filmRes.y / M_PI);
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m_logRatio = -math::fastlog(m_r2/m_r1);
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//Log(EInfo, "Expected jump distance: %f", (m_r1-m_r2)/m_logRatio);
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}
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LensPerturbation::~LensPerturbation() { }
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Mutator::EMutationType LensPerturbation::getType() const {
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return ELensPerturbation;
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}
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Float LensPerturbation::suitability(const Path &path) const {
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int k = path.length(), m = k - 1, l = m-1;
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while (l >= 0 && !path.vertex(l)->isConnectable())
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--l;
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--l;
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return (l >= 0 && path.vertex(l)->isConnectable()
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&& path.vertex(l+1)->isConnectable()) ? 1.0f : 0.0f;
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}
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bool LensPerturbation::sampleMutation(
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Path &source, Path &proposal, MutationRecord &muRec, const MutationRecord& sourceMuRec) {
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int k = source.length(), m = k-1, l = m-1;
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while (!source.vertex(l)->isConnectable() && l >= 0)
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--l;
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--l;
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muRec = MutationRecord(ELensPerturbation, l, m, m-l,
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source.getPrefixSuffixWeight(l, m));
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statsAccepted.incrementBase();
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statsGenerated.incrementBase();
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/* Generate a screen-space offset */
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Float r = m_r2 * math::fastexp(m_logRatio * m_sampler->next1D());
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Float phi = m_sampler->next1D() * 2 * M_PI;
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Vector2 offset(r*std::cos(phi), r*std::sin(phi));
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Point2 proposalSamplePosition = source.getSamplePosition() + offset;
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/* Immediately reject if we went off the image plane */
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if (proposalSamplePosition.x <= 0 || proposalSamplePosition.x >= m_filmRes.x
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|| proposalSamplePosition.y <= 0 || proposalSamplePosition.y >= m_filmRes.y)
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return false;
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const PerspectiveCamera *sensor = static_cast<const PerspectiveCamera *>(m_scene->getSensor());
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Ray ray;
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if (sensor->sampleRay(ray, proposalSamplePosition, Point2(0.5f), 0.0f).isZero())
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return false;
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Float focusDistance = sensor->getFocusDistance() /
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absDot(sensor->getWorldTransform(0)(Vector(0,0,1)), ray.d);
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/* Correct direction based on the current aperture sample.
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This is necessary to support thin lens cameras */
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Vector d = normalize(ray(focusDistance) - source.vertex(m)->getPosition());
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Float dist = source.edge(m-1)->length;
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/* Allocate memory for the proposed path */
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proposal.clear();
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proposal.append(source, 0, l);
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if (l > 0)
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proposal.append(source.edge(l-1));
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proposal.append(source.vertex(l)->clone(m_pool));
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for (int i=l; i<m-1; ++i) {
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proposal.append(m_pool.allocEdge());
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proposal.append(m_pool.allocVertex());
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}
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proposal.append(m_pool.allocEdge());
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proposal.append(source.vertex(m)->clone(m_pool));
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proposal.append(source.edge(m));
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proposal.append(source.vertex(k));
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BDAssert(proposal.vertexCount() == source.vertexCount());
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BDAssert(proposal.edgeCount() == source.edgeCount());
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dist += perturbMediumDistance(m_sampler, source.vertex(m-1));
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/* Sample a perturbation and propagate it through specular interactions */
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if (!proposal.vertex(m)->perturbDirection(m_scene,
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proposal.vertex(k), proposal.edge(m),
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proposal.edge(m-1), proposal.vertex(m-1), d, dist,
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source.vertex(m-1)->getType(), ERadiance)) {
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proposal.release(l, m+1, m_pool);
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return false;
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}
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/* If necessary, propagate the perturbation through a sequence of
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ideally specular interactions */
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for (int i=m-1; i>l+1; --i) {
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Float dist = source.edge(i-1)->length +
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perturbMediumDistance(m_sampler, source.vertex(i-1));
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if (!proposal.vertex(i)->propagatePerturbation(m_scene,
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proposal.vertex(i+1), proposal.edge(i),
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proposal.edge(i-1), proposal.vertex(i-1),
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source.vertex(i)->getComponentType(), dist,
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source.vertex(i-1)->getType(), ERadiance)) {
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proposal.release(l, m+1, m_pool);
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return false;
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}
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}
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if (!PathVertex::connect(m_scene,
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l > 0 ? proposal.vertex(l-1) : NULL,
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l > 0 ? proposal.edge(l-1) : NULL,
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proposal.vertex(l),
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proposal.edge(l),
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proposal.vertex(l+1),
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proposal.edge(l+1),
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proposal.vertex(l+2))) {
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proposal.release(l, m+1, m_pool);
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return false;
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}
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proposal.vertex(k-1)->updateSamplePosition(
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proposal.vertex(k-2));
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BDAssert(proposal.matchesConfiguration(source));
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++statsGenerated;
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return true;
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}
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Float LensPerturbation::Q(const Path &source, const Path &proposal,
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const MutationRecord &muRec) const {
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int m = muRec.m, l = muRec.l;
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Spectrum weight = muRec.weight *
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proposal.edge(l)->evalCached(proposal.vertex(l), proposal.vertex(l+1),
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PathEdge::EEverything);
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for (int i=m; i>l+1; --i) {
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const PathVertex *v0 = proposal.vertex(i-1),
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*v1 = proposal.vertex(i);
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const PathEdge *edge = proposal.edge(i-1);
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weight *= edge->evalCached(v0, v1,
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PathEdge::ETransmittance |
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(i != m ? PathEdge::EValueCosineRad : 0));
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if (v0->isMediumInteraction())
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weight /= pdfMediumPerturbation(source.vertex(i-1),
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source.edge(i-1), edge);
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}
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const Float lumWeight = weight.getLuminance();
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if(lumWeight <= RCPOVERFLOW)
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return 0.f;
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return 1.0f / lumWeight;
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}
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void LensPerturbation::accept(const MutationRecord &) {
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++statsAccepted;
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}
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MTS_IMPLEMENT_CLASS(LensPerturbation, false, Mutator)
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MTS_NAMESPACE_END
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