fixing 2-stage MLT, part 1

include/mitsuba/bidir/pathsampler.h

@@ -165,7 +165,8 @@ public:
 	 * \return The average luminance over the image plane
 	 */
 	Float generateSeeds(size_t sampleCount, size_t seedCount,
-			bool fineGrained, std::vector<PathSeed> &seeds);
+			bool fineGrained, const Bitmap *importanceMap,
+			std::vector<PathSeed> &seeds);
 
 	/**
 	 * \brief Compute the average luminance over the image plane
@@ -181,7 +182,8 @@ public:
 	 * the random number stream of the underlying \ref ReplayableSampler
 	 * to the indicated position and recreates the associated path.
 	 */
-	void reconstructPath(const PathSeed &seed, Path &result);
+	void reconstructPath(const PathSeed &seed, 
+		const Bitmap *importanceMap, Path &result);
 
 	/// Return the underlying memory pool
 	inline MemoryPool &getMemoryPool() { return m_pool; }

src/integrators/mlt/mlt.cpp

@@ -290,7 +290,7 @@ public:
 				m_config, directImage, pathSeeds);
 
 		m_config.luminance = pathSampler->generateSeeds(m_config.luminanceSamples,
-			m_config.workUnits, true, pathSeeds);
+			m_config.workUnits, true, m_config.importanceMap, pathSeeds);
 
 		if (!nested)
 			m_config.dump();

src/integrators/mlt/mlt_proc.cpp

@@ -122,7 +122,7 @@ public:
 		result->clear();
 
 		/// Reconstruct the seed path
-		m_pathSampler->reconstructPath(wu->getSeed(), *current);
+		m_pathSampler->reconstructPath(wu->getSeed(), m_config.importanceMap, *current);
 		relWeight = current->getRelativeWeight();
 		BDAssert(!relWeight.isZero());
 
@@ -367,6 +367,7 @@ void MLTProcess::develop() {
 			value += direct[i];
 		target[i] = value;
 	}
+
 	m_film->setBitmap(m_developBuffer);
 	m_refreshTimer->reset();
 

src/integrators/pssmlt/pssmlt.cpp

@@ -344,7 +344,7 @@ public:
 				m_config, directImage, pathSeeds);
 
 		m_config.luminance = pathSampler->generateSeeds(m_config.luminanceSamples,
-			m_config.workUnits, false, pathSeeds);
+			m_config.workUnits, false, m_config.importanceMap, pathSeeds);
 
 		if (!nested)
 			m_config.dump();

src/libbidir/pathsampler.cpp

@@ -579,12 +579,24 @@ Float PathSampler::computeAverageLuminance(size_t sampleCount) {
 	return mean;
 }
 
-static void seedCallback(std::vector<PathSeed> &output, int s, int t, Float weight, Path &) {
+static void seedCallback(std::vector<PathSeed> &output, const Bitmap *importanceMap,
+		int s, int t, Float weight, Path &path) {
+	if (importanceMap) {
+		const Float *luminanceValues = importanceMap->getFloatData();
+		Vector2i size = importanceMap->getSize();
+
+		const Point2 &pos = path.getSamplePosition();
+		Point2i intPos(
+			std::min(std::max(0, (int) pos.x), size.x-1),
+			std::min(std::max(0, (int) pos.y), size.y-1));
+		weight /= luminanceValues[intPos.x + intPos.y * size.x];
+	}
+
 	output.push_back(PathSeed(0, weight, s, t));
 }
 
 Float PathSampler::generateSeeds(size_t sampleCount, size_t seedCount,
-		bool fineGrained, std::vector<PathSeed> &seeds) {
+		bool fineGrained, const Bitmap *importanceMap, std::vector<PathSeed> &seeds) {
 	Log(EInfo, "Integrating luminance values over the image plane ("
 			SIZE_T_FMT " samples)..", sampleCount);
 
@@ -597,7 +609,7 @@ Float PathSampler::generateSeeds(size_t sampleCount, size_t seedCount,
 
 	SplatList splatList;
 	PathCallback callback = boost::bind(&seedCallback,
-		boost::ref(tempSeeds), _1, _2, _3, _4);
+		boost::ref(tempSeeds), importanceMap, _1, _2, _3, _4);
 
 	Float mean = 0.0f, variance = 0.0f;
 	for (size_t i=0; i<sampleCount; ++i) {
@@ -617,6 +629,7 @@ Float PathSampler::generateSeeds(size_t sampleCount, size_t seedCount,
 		} else {
 			/* Run the path sampling strategy */
 			sampleSplats(Point2i(-1), splatList);
+			splatList.normalize(importanceMap);
 			lum = splatList.luminance;
 
 			/* Coarse seed granularity (e.g. for PSSMLT) */
@@ -659,9 +672,20 @@ Float PathSampler::generateSeeds(size_t sampleCount, size_t seedCount,
 	return mean;
 }
 
-static void reconstructCallback(const PathSeed &seed, Path &result, MemoryPool &pool,
-	int s, int t, Float weight, Path &path) {
+static void reconstructCallback(const PathSeed &seed, const Bitmap *importanceMap,
+		Path &result, MemoryPool &pool, int s, int t, Float weight, Path &path) {
 	if (s == seed.s && t == seed.t) {
+		if (importanceMap) {
+			const Float *luminanceValues = importanceMap->getFloatData();
+			Vector2i size = importanceMap->getSize();
+
+			const Point2 &pos = path.getSamplePosition();
+			Point2i intPos(
+				std::min(std::max(0, (int) pos.x), size.x-1),
+				std::min(std::max(0, (int) pos.y), size.y-1));
+			weight /= luminanceValues[intPos.x + intPos.y * size.x];
+		}
+
 		if (seed.luminance != weight)
 			SLog(EError, "Internal error in reconstructPath(): luminances "
 				"don't match (%f vs %f)!", weight, seed.luminance);
@@ -669,7 +693,7 @@ static void reconstructCallback(const PathSeed &seed, Path &result, MemoryPool &
 	}
 }
 
-void PathSampler::reconstructPath(const PathSeed &seed, Path &result) {
+void PathSampler::reconstructPath(const PathSeed &seed, const Bitmap *importanceMap, Path &result) {
 	ReplayableSampler *rplSampler = static_cast<ReplayableSampler *>(m_sensorSampler.get());
 	Assert(result.length() == 0);
 
@@ -678,7 +702,8 @@ void PathSampler::reconstructPath(const PathSeed &seed, Path &result) {
 	rplSampler->setSampleIndex(seed.sampleIndex);
 
 	PathCallback callback = boost::bind(&reconstructCallback,
-		boost::cref(seed), boost::ref(result), boost::ref(m_pool), _1, _2, _3, _4);
+		boost::cref(seed), importanceMap,
+		boost::ref(result), boost::ref(m_pool), _1, _2, _3, _4);
 
 	samplePaths(Point2i(-1), callback);