Files
OpenSpace/modules/multiresvolume/rendering/tfbrickselector.cpp
2016-05-17 12:49:16 -04:00

396 lines
17 KiB
C++

/*****************************************************************************************
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* OpenSpace *
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* Copyright (c) 2015 *
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#include <modules/multiresvolume/rendering/tsp.h>
#include <modules/multiresvolume/rendering/tfbrickselector.h>
#include <modules/multiresvolume/rendering/errorhistogrammanager.h>
#include <openspace/util/histogram.h>
#include <openspace/rendering/transferfunction.h>
#include <algorithm>
#include <cassert>
namespace {
const std::string _loggerCat = "TfBrickSelector";
}
namespace openspace {
TfBrickSelector::TfBrickSelector(TSP* tsp, ErrorHistogramManager* hm, TransferFunction* tf, int memoryBudget, int streamingBudget)
: _tsp(tsp)
, _histogramManager(hm)
, _transferFunction(tf)
, _memoryBudget(memoryBudget)
, _streamingBudget(streamingBudget) {}
TfBrickSelector::~TfBrickSelector() {}
bool TfBrickSelector::initialize() {
return calculateBrickErrors();
}
void TfBrickSelector::setMemoryBudget(int memoryBudget) {
_memoryBudget = memoryBudget;
}
void TfBrickSelector::setStreamingBudget(int streamingBudget) {
_streamingBudget = streamingBudget;
}
void TfBrickSelector::selectBricks(int timestep, std::vector<int>& bricks) {
int numTimeSteps = _tsp->header().numTimesteps_;
int numBricksPerDim = _tsp->header().xNumBricks_;
unsigned int rootNode = 0;
BrickSelection::SplitType splitType;
float rootSplitPoints = splitPoints(rootNode, splitType);
BrickSelection brickSelection = BrickSelection(numBricksPerDim, numTimeSteps, splitType, rootSplitPoints);
std::vector<BrickSelection> priorityQueue;
std::vector<BrickSelection> leafSelections;
std::vector<BrickSelection> temporalSplitQueue;
std::vector<BrickSelection> deadEnds;
if (splitType != BrickSelection::SplitType::None) {
priorityQueue.push_back(brickSelection);
} else {
leafSelections.push_back(brickSelection);
}
int memoryBudget = _memoryBudget;
int totalStreamingBudget = _streamingBudget * numTimeSteps;
int nBricksInMemory = 1;
int nStreamedBricks = 1;
// First loop: While neither the memory nor the streaming budget is reached,
// try to optimize for visual quality vs memory.
while (nBricksInMemory <= memoryBudget - 7 && priorityQueue.size() > 0) {
std::pop_heap(priorityQueue.begin(), priorityQueue.end(), BrickSelection::compareSplitPoints);
BrickSelection bs = priorityQueue.back();
unsigned int brickIndex = bs.brickIndex;
priorityQueue.pop_back();
// TODO: handle edge case when we can only afford temporal splits or no split (only 1 spot left)
if (bs.splitType == BrickSelection::SplitType::Temporal) {
unsigned int childBrickIndex;
bool pickRightTimeChild = bs.timestepInRightChild(timestep);
// assert(!pickRightTimeChild && "picked right child");
// On average on the whole time period, splitting this spatial brick in two time steps
// would generate twice as much streaming. Current number of streams of this spatial brick
// is 2^nTemporalSplits over the whole time period.
int newStreams = std::pow(2, bs.nTemporalSplits);
//std::cout << "preparing for " << newStreams << " new streams" << std::endl;
// Refining this one more step would require the double amount of streams
if (nStreamedBricks + newStreams > totalStreamingBudget) {
//std::cout << "Reached streaming budget when splitting temporally! Breaking" << std::endl;
// Reached dead end (streaming budget would be exceeded)
deadEnds.push_back(bs);
break;
}
nStreamedBricks += newStreams;
if (pickRightTimeChild) {
childBrickIndex = _tsp->getBstRight(brickIndex);
} else {
childBrickIndex = _tsp->getBstLeft(brickIndex);
}
BrickSelection::SplitType childSplitType;
float childSplitPoints = splitPoints(childBrickIndex, childSplitType);
BrickSelection childSelection = bs.splitTemporally(pickRightTimeChild, childBrickIndex, childSplitType, childSplitPoints);
if (childSplitType != BrickSelection::SplitType::None) {
priorityQueue.push_back(childSelection);
std::push_heap(priorityQueue.begin(), priorityQueue.end(), BrickSelection::compareSplitPoints);
} else {
leafSelections.push_back(childSelection);
}
} else if (bs.splitType == BrickSelection::SplitType::Spatial) {
nBricksInMemory += 7; // Remove one and add eight.
unsigned int firstChild = _tsp->getFirstOctreeChild(brickIndex);
// On average on the whole time period, splitting this spatial brick into eight spatial bricks
// would generate eight times as much streaming. Current number of streams of this spatial brick
// is 2^nTemporalStreams over the whole time period.
int newStreams = 7*std::pow(2, bs.nTemporalSplits);
if (nStreamedBricks + newStreams > totalStreamingBudget) {
// Reached dead end (streaming budget would be exceeded)
// However, temporal split might be possible
//std::cout << "Reached streaming budget when splitting spatially! Breaking" << std::endl;
if (bs.splitType != BrickSelection::SplitType::Temporal) {
bs.splitType = BrickSelection::SplitType::Temporal;
bs.splitPoints = temporalSplitPoints(bs.brickIndex);
}
if (bs.splitPoints > -1) {
temporalSplitQueue.push_back(bs);
} else {
deadEnds.push_back(bs);
}
break;
}
nStreamedBricks += newStreams;
for (unsigned int i = 0; i < 8; i++) {
unsigned int childBrickIndex = firstChild + i;
BrickSelection::SplitType childSplitType;
float childSplitPoints = splitPoints(childBrickIndex, childSplitType);
//std::cout << "Splitting spatially." << std::endl;
BrickSelection childSelection = bs.splitSpatially(i % 2, (i/2) % 2, i/4, childBrickIndex, childSplitType, childSplitPoints);
if (childSplitType != BrickSelection::SplitType::None) {
priorityQueue.push_back(childSelection);
std::push_heap(priorityQueue.begin(), priorityQueue.end(), BrickSelection::compareSplitPoints);
} else {
leafSelections.push_back(childSelection);
}
}
}
}
if (nBricksInMemory <= memoryBudget - 7) {
//std::cout << "memory budget not reached. " << nBricksInMemory << " out of " << memoryBudget << std::endl;
}
// Is it possible that we may stream more bricks?
if (nStreamedBricks < totalStreamingBudget - 1) {
//std::cout << "streaming budget not reached. " << nStreamedBricks << " out of " << totalStreamingBudget << std::endl;
//std::cout << "there are " << priorityQueue.size() << " elements left in priority queue." << std::endl;
while (priorityQueue.size() > 0) {
BrickSelection bs = priorityQueue.back();
if (bs.splitType != BrickSelection::SplitType::Temporal) {
bs.splitType = BrickSelection::SplitType::Temporal;
bs.splitPoints = temporalSplitPoints(bs.brickIndex);
}
priorityQueue.pop_back();
if (bs.splitPoints > -1) {
temporalSplitQueue.push_back(bs);
std::push_heap(temporalSplitQueue.begin(), temporalSplitQueue.end(), BrickSelection::compareSplitPoints);
} else {
deadEnds.push_back(bs);
}
}
// Keep splitting until it's not possible anymore
while (nStreamedBricks < totalStreamingBudget - 1 && temporalSplitQueue.size() > 0) {
std::pop_heap(temporalSplitQueue.begin(), temporalSplitQueue.end(), BrickSelection::compareSplitPoints);
BrickSelection bs = temporalSplitQueue.back();
temporalSplitQueue.pop_back();
unsigned int brickIndex = bs.brickIndex;
int newStreams = std::pow(2, bs.nTemporalSplits);
if (nStreamedBricks + newStreams > totalStreamingBudget) {
// The current best choice would make us exceed the streaming budget, try next instead.
deadEnds.push_back(bs);
//std::cout << "Dead end trying to split " << brickIndex << ". Streamed would be " << (nStreamedBricks + newStreams) << std::endl;
continue;
}
nStreamedBricks += newStreams;
unsigned int childBrickIndex;
bool pickRightTimeChild = bs.timestepInRightChild(timestep);
if (pickRightTimeChild) {
childBrickIndex = _tsp->getBstRight(brickIndex);
} else {
childBrickIndex = _tsp->getBstLeft(brickIndex);
}
float childSplitPoints = temporalSplitPoints(childBrickIndex);
if (childSplitPoints > -1) {
BrickSelection childSelection = bs.splitTemporally(pickRightTimeChild, childBrickIndex, BrickSelection::SplitType::Temporal, childSplitPoints);
temporalSplitQueue.push_back(childSelection);
std::push_heap(temporalSplitQueue.begin(), temporalSplitQueue.end(), BrickSelection::compareSplitPoints);
} else {
BrickSelection childSelection = bs.splitTemporally(pickRightTimeChild, childBrickIndex, BrickSelection::SplitType::None, -1);
deadEnds.push_back(childSelection);
}
}
} else {
// Write selected inner nodes to brickSelection vector
//std::cout << "priority queue: " << priorityQueue.size() << std::endl;
for (const BrickSelection& bs : priorityQueue) {
writeSelection(bs, bricks);
}
}
//std::cout << "temporal split queue: " << temporalSplitQueue.size() << std::endl;
// Write selected inner nodes to brickSelection vector
for (const BrickSelection& bs : temporalSplitQueue) {
writeSelection(bs, bricks);
}
//std::cout << "dead ends: " << deadEnds.size() << std::endl;
for (const BrickSelection& bs : deadEnds) {
writeSelection(bs, bricks);
}
// Write selected leaf nodes to brickSelection vector
//std::cout << "leaf selections: " << leafSelections.size() << std::endl;
for (const BrickSelection& bs : leafSelections) {
writeSelection(bs, bricks);
}
//std::cout << "Bricks in memory: " << nBricksInMemory << "/" << _memoryBudget << "___\t\t"
// << "Streamed bricks: " << nStreamedBricks << "/" << totalStreamingBudget << std::flush << "___\r";
}
float TfBrickSelector::temporalSplitPoints(unsigned int brickIndex) {
if (_tsp->isBstLeaf(brickIndex)) {
return -1;
}
unsigned int leftChild = _tsp->getBstLeft(brickIndex);
unsigned int rightChild = _tsp->getBstRight(brickIndex);
float currentError = _brickErrors[brickIndex];
float splitError = _brickErrors[leftChild] + _brickErrors[rightChild];
/*if (currentError + 0.001 < splitError) {
std::cout << "Warning! (TEMPORAL SPLIT) Current error " << currentError << " is smaller than split error " << splitError << "." << std::endl;
}*/
float diff = currentError - splitError;
if (diff < 0.0) {
//std::cout << "local temporal split minimum for brick " << brickIndex << std::endl;
diff = -diff;
}
return diff * 0.5;
}
float TfBrickSelector::spatialSplitPoints(unsigned int brickIndex) {
if (_tsp->isOctreeLeaf(brickIndex)) {
return -1;
}
float currentError = _brickErrors[brickIndex];
float splitError = 0;
unsigned int firstChild = _tsp->getFirstOctreeChild(brickIndex);
for (unsigned int i = 0; i < 8; i++) {
unsigned int child = firstChild + i;
splitError += _brickErrors[child];
}
/*if (currentError + 0.001 < splitError) {
std::cout << "Warning! (SPATIAL SPLIT) Current error " << currentError << " is smaller than split error " << splitError << "." << std::endl;
}*/
float diff = currentError - splitError;
if (diff < 0.0) {
//std::cout << "local spatial split minimum for brick " << brickIndex << std::endl;
diff = -diff;
}
return diff * 0.125;
}
float TfBrickSelector::splitPoints(unsigned int brickIndex, BrickSelection::SplitType& splitType) {
float temporalPoints = temporalSplitPoints(brickIndex);
float spatialPoints = spatialSplitPoints(brickIndex);
float splitPoints;
if (spatialPoints > 0 && spatialPoints > temporalPoints) {
splitPoints = spatialPoints;
splitType = BrickSelection::SplitType::Spatial;
} else if (temporalPoints > 0) {
splitPoints = temporalPoints;
splitType = BrickSelection::SplitType::Temporal;
} else {
splitPoints = -1;
splitType = BrickSelection::SplitType::None;
}
return splitPoints;
}
bool TfBrickSelector::calculateBrickErrors() {
TransferFunction *tf = _transferFunction;
if (!tf) return false;
size_t tfWidth = tf->width();
if (tfWidth <= 0) return false;
std::vector<float> gradients(tfWidth - 1);
for (size_t offset = 0; offset < tfWidth - 1; offset++) {
glm::vec4 prevRgba = tf->sample(offset);
glm::vec4 nextRgba = tf->sample(offset + 1);
float colorDifference = glm::distance(prevRgba, nextRgba);
float alpha = (prevRgba.w + nextRgba.w) * 0.5;
gradients[offset] = colorDifference*alpha;
}
unsigned int nHistograms = _tsp->numTotalNodes();
_brickErrors = std::vector<float>(nHistograms);
for (unsigned int brickIndex = 0; brickIndex < nHistograms; brickIndex++) {
if (_tsp->isBstLeaf(brickIndex) && _tsp->isOctreeLeaf(brickIndex)) {
_brickErrors[brickIndex] = 0;
} else {
const Histogram* histogram = _histogramManager->getHistogram(brickIndex);
float error = 0;
for (int i = 0; i < gradients.size(); i++) {
float x = (i + 0.5) / tfWidth;
float sample = histogram->interpolate(x);
assert(sample >= 0);
assert(gradients[i] >= 0);
error += sample * gradients[i];
}
_brickErrors[brickIndex] = error;
}
}
return true;
}
int TfBrickSelector::linearCoords(int x, int y, int z) {
const TSP::Header &header = _tsp->header();
return x + (header.xNumBricks_ * y) + (header.xNumBricks_ * header.yNumBricks_ * z);
}
void TfBrickSelector::writeSelection(BrickSelection brickSelection, std::vector<int>& bricks) {
BrickCover coveredBricks = brickSelection.cover;
for (int z = coveredBricks.lowZ; z < coveredBricks.highZ; z++) {
for (int y = coveredBricks.lowY; y < coveredBricks.highY; y++) {
for (int x = coveredBricks.lowX; x < coveredBricks.highX; x++) {
bricks[linearCoords(x, y, z)] = brickSelection.brickIndex;
}
}
}
}
} // namespace openspace