Graph viewer optimizations (#1616)

* DbViewer: coloring graph based on env sensor value (e.g., wifi signal strength) * GraphViewer optimizations * Fixed link memory allocation * refactor * more optimizations * mainwindow keypoints optimization * MainWindow optimizations * Shrink graphics scene on clearAll
2026-10-05 17:47:49 +08:00 · 2025-11-16 18:56:55 -08:00
parent 82fb7ff5d2
commit e75baec73e
5 changed files with 579 additions and 490 deletions
@@ -337,17 +337,37 @@ GraphViewer::GraphViewer(QWidget * parent) :
 		_gridCellSize(0.0f),
 		_localRadius(0),
 		_loopClosureOutlierThr(0),
-		_maxLinkLength(0.02f),
+		_minLinkLength(0.02f),
 		_orientationENU(false),
 		_mouseTracking(false),
 		_viewPlane(XY),
 		_ensureFrameVisible(true)
 {
-	this->setScene(new QGraphicsScene(this));
 	this->setDragMode(QGraphicsView::ScrollHandDrag);
 	_workingDirectory = QDir::homePath();

-	this->scene()->clear();
+	setupGraphicsScene();
+
+	// Match by default scan colors from DatabaseViewer
+	_highlightedNodes.push_back(QPair<QColor, NodeItem*>(Qt::yellow, nullptr));
+	_highlightedNodes.push_back(QPair<QColor, NodeItem*>(Qt::magenta, nullptr));
+
+	this->restoreDefaults();
+
+	this->fitInView(this->sceneRect(), Qt::KeepAspectRatio);
+}
+
+GraphViewer::~GraphViewer()
+{
+}
+
+void GraphViewer::setupGraphicsScene()
+{
+	if(this->scene())
+	{
+		delete this->scene();
+	}
+	this->setScene(new QGraphicsScene(this));
 	_world = (QGraphicsItem *)this->scene()->addEllipse(QRectF(-0.0001,-0.0001,0.0001,0.0001));
 	_root = (QGraphicsItem *)this->scene()->addEllipse(QRectF(-0.0001,-0.0001,0.0001,0.0001));
 	_root->setParentItem(_world);
@@ -485,17 +505,6 @@ GraphViewer::GraphViewer(QWidget * parent) :
 	_odomCacheOverlay->setBrush(QBrush(QColor(255, 255, 255, 150)));
 	_odomCacheOverlay->setPen(QPen(Qt::NoPen));

-	// Match by default scan colors from DatabaseViewer
-	_highlightedNodes.push_back(QPair<QColor, NodeItem*>(Qt::yellow, nullptr));
-	_highlightedNodes.push_back(QPair<QColor, NodeItem*>(Qt::magenta, nullptr));
-
-	this->restoreDefaults();
-
-	this->fitInView(this->sceneRect(), Qt::KeepAspectRatio);
-}
-
-GraphViewer::~GraphViewer()
-{
 }

 void GraphViewer::setWorldMapRotation(const float & theta)
@@ -510,18 +519,48 @@ void GraphViewer::updateGraph(const std::map<int, Transform> & poses,
 				 const std::map<int, int> & weights,
 				 const std::set<int> & odomCacheIds)
 {
-	UTimer timer;
-	bool wasVisible = _graphRoot->isVisible();
-	_graphRoot->show();
-
-	bool wasEmpty = _nodeItems.size() == 0 && _linkItems.size() == 0;
-	UDEBUG("poses=%d constraints=%d", (int)poses.size(), (int)constraints.size());
-	//Hide nodes and links
-	for(QMap<int, NodeItem*>::iterator iter = _nodeItems.begin(); iter!=_nodeItems.end(); ++iter)
+	if(!_graphRoot->isVisible())
 	{
+		UDEBUG("Ignoring updating graph, the graph root is not visible.");
+		return;
+	}
+
+	UTimer timer;
+
+	bool wasEmpty = _nodeItems.size() == 0 && _linkItems.size() == 0 && _gridMap->pixmap().isNull();
+	UDEBUG("poses=%ld constraints=%ld mapIds=%ld weights=%ld", poses.size(), constraints.size(), mapIds.size(), weights.size());
+	for(QMultiMap<int, LinkItem*>::iterator iter = _linkItems.begin(); iter!=_linkItems.end(); ++iter)
+	{
+		iter.value()->hide();
+	}
+	UDEBUG("hidden %d links", _linkItems.size());
+
+	int created = 0;
+	int reused = 0;
+	int removed = 0;
+	QMap<int, NodeItem*>::iterator nter = _nodeItems.begin();
+	std::map<int, Transform>::const_iterator iter=_nodeVisible?poses.begin():poses.end();
+	while(nter!=_nodeItems.end() || iter!=poses.end())
+	{
+		if(nter!=_nodeItems.end() && (iter==poses.end() || nter.key() < iter->first || iter->second.isNull()))
+		{
+			// NodeItem is not in poses anymore, increase only _nodeItems iterator
+			for(int i=0; i<_highlightedNodes.size(); ++i)
+			{
+				if(_highlightedNodes[i].second && _highlightedNodes[i].second == nter.value())
+				{
+					_highlightedNodes[i].second = nullptr;
+				}
+			}
+			delete nter.value();
+			nter = _nodeItems.erase(nter);
+			++removed;
+			continue;
+		}
+
 		QColor color = _nodeColor;
-		bool isOdomCache = odomCacheIds.find(iter.key()) != odomCacheIds.end();
-		if(iter.key()<0)
+		bool isOdomCache = odomCacheIds.find(iter->first) != odomCacheIds.end();
+		if(iter->first<0)
 		{
 			color = QColor(255-color.red(), 255-color.green(), 255-color.blue());
 		}
@@ -529,51 +568,50 @@ void GraphViewer::updateGraph(const std::map<int, Transform> & poses,
 		{
 			color = _nodeOdomCacheColor;
 		}
-		iter.value()->hide();
-		iter.value()->setColor(color); // reset color
-		iter.value()->setToolTipInfo(QString());
-		iter.value()->setZValue(iter.key()<0?21:20);
-	}
-	for(QMultiMap<int, LinkItem*>::iterator iter = _linkItems.begin(); iter!=_linkItems.end(); ++iter)
-	{
-		iter.value()->hide();
-	}

-	for(std::map<int, Transform>::const_iterator iter=poses.begin(); iter!=poses.end(); ++iter)
-	{
-		if(!iter->second.isNull())
+		UASSERT(iter!=poses.end());
+
+		if(nter == _nodeItems.end() || nter.key() > iter->first)
 		{
-			QMap<int, NodeItem*>::iterator itemIter = _nodeItems.find(iter->first);
-			if(itemIter != _nodeItems.end())
-			{
-				itemIter.value()->setPose(iter->second, _viewPlane);
-				itemIter.value()->show();
-			}
-			else
-			{
-				// create node item
-				QColor color = _nodeColor;
-				bool isOdomCache = odomCacheIds.find(iter->first) != odomCacheIds.end();
-				if(iter->first<0)
-				{
-					color = QColor(255-color.red(), 255-color.green(), 255-color.blue());
-				}
-				else if(isOdomCache)
-				{
-					color = _nodeOdomCacheColor;
-				}
-				const Transform & pose = iter->second;
-				NodeItem * item = new NodeItem(iter->first, uContains(mapIds, iter->first)?mapIds.at(iter->first):-1, pose, _nodeRadius, uContains(weights, iter->first)?weights.at(iter->first):-1, _viewPlane, _linkWidth);
-				this->scene()->addItem(item);
-				item->setZValue(iter->first<0?21:20);
-				item->setColor(color);
-				item->setParentItem(_graphRoot);
-				item->show();
-				_nodeItems.insert(iter->first, item);
-			}
+			// NodeItem is not in poses, create a new one and increase poses iterator
+			const Transform & pose = iter->second;
+			NodeItem * item = new NodeItem(
+				iter->first, 
+				uValue(mapIds, iter->first, -1), 
+				pose, 
+				_nodeRadius,
+				uValue(weights, iter->first, -1), 
+				_viewPlane, 
+				_linkWidth);
+			this->scene()->addItem(item);
+			item->setZValue(iter->first<0?21:20);
+			item->setColor(color);
+			item->setParentItem(_graphRoot);
+			item->show();
+			_nodeItems.insert(iter->first, item);
+			++iter;
+			++created;
+		}
+		else
+		{
+			// NodeItem exists for the pose, copy data and increase both iterators
+			UASSERT(iter->first == nter.key());
+			nter.value()->setColor(color); // reset color
+			nter.value()->setToolTipInfo(QString());
+			nter.value()->setZValue(iter->first<0?21:20);
+			nter.value()->setPose(iter->second, _viewPlane);
+			nter.value()->show();
+			++nter;
+			++iter;
+			++reused;
 		}
 	}
-
+	UDEBUG("Nodes created=%d, reused=%d removed=%d", created, reused, removed);
+	created = 0;
+	reused = 0;
+	removed = 0;
+	int removedSmallLinks = 0;
+	int ignoredSmallLinks = 0;
 	for(std::multimap<int, Link>::const_iterator iter=constraints.begin(); iter!=constraints.end(); ++iter)
 	{
 		// make the first id the smallest one
@@ -587,30 +625,28 @@ void GraphViewer::updateGraph(const std::map<int, Transform> & poses,
 		std::map<int, Transform>::const_iterator jterA = poses.find(idFrom);
 		std::map<int, Transform>::const_iterator jterB = poses.find(idTo);
 		LinkItem * linkItem = 0;
-		if(jterA != poses.end() && jterB != poses.end() &&
-		   _nodeItems.contains(idFrom) && _nodeItems.contains(idTo))
+		if(jterA != poses.end() && jterB != poses.end())
 		{
 			const Transform & poseA = jterA->second;
 			const Transform & poseB = jterB->second;

-			QMultiMap<int, LinkItem*>::iterator itemIter = _linkItems.end();
-
-			if(_linkItems.contains(idFrom))
+			QMultiMap<int, LinkItem*>::iterator itemIter = _linkItems.find(idFrom);
+			bool alreadyAdded = false;
+			while(itemIter != _linkItems.end() && itemIter.key() == idFrom)
 			{
-				itemIter = _linkItems.find(idFrom);
-				bool alreadyAdded = false;
-				while(itemIter != _linkItems.end() && itemIter.key() == idFrom)
+				if(itemIter.value()->to() == idTo)
 				{
-					if(itemIter.value()->to() == idTo && itemIter.value()->isVisible())
-					{
+					if(itemIter.value()->isVisible()) {
 						alreadyAdded = true;
-						break;
+					} else {
+						linkItem = itemIter.value();
 					}
-					++itemIter;
-				}
-				if(alreadyAdded){
-					continue;
+					break;
 				}
+				++itemIter;
+			}
+			if(alreadyAdded){
+				continue;
 			}

 			bool interSessionClosure = false;
@@ -625,11 +661,15 @@ void GraphViewer::updateGraph(const std::map<int, Transform> & poses,

 			if(isLinkedToOdomCachePoses)
 			{
-				_nodeItems.value(idFrom)->setZValue(odomCacheIds.find(idFrom)!=odomCacheIds.end()?24:23);
-				_nodeItems.value(idTo)->setZValue(odomCacheIds.find(idTo)!=odomCacheIds.end()?24:23);
+				if(_nodeItems.contains(idFrom)) {
+					_nodeItems.value(idFrom)->setZValue(odomCacheIds.find(idFrom)!=odomCacheIds.end()?24:23);
+				}
+				if(_nodeItems.contains(idTo)) {
+					_nodeItems.value(idTo)->setZValue(odomCacheIds.find(idTo)!=odomCacheIds.end()?24:23);
+				}
 			}

-			if(poseA.getDistance(poseB) > _maxLinkLength)
+			if(poseA.getDistance(poseB) > _minLinkLength)
 			{
 				if(linkItem == 0)
 				{
@@ -642,14 +682,24 @@ void GraphViewer::updateGraph(const std::map<int, Transform> & poses,
 					this->scene()->addItem(linkItem);
 					linkItem->setParentItem(_graphRoot);
 					_linkItems.insert(idFrom, linkItem);
+					++created;
+				}
+				else {
+					linkItem->setPoses(poseA, poseB, _viewPlane);
+					linkItem->show();
+					++reused;
 				}
 			}
-			else if(linkItem && itemIter != _linkItems.end())
+			else if(linkItem)
 			{
 				// erase small links
 				_linkItems.erase(itemIter);
 				delete linkItem;
 				linkItem = 0;
+				++removedSmallLinks;
+			}
+			else {
+				++ignoredSmallLinks;
 			}

 			if(linkItem)
@@ -730,71 +780,48 @@ void GraphViewer::updateGraph(const std::map<int, Transform> & poses,
 			}
 		}
 	}
-
+	UDEBUG("Links created=%d, reused=%d, small links: removed=%d ignored=%d", created, reused, removedSmallLinks, ignoredSmallLinks);
 	//remove not used nodes and links
-	for(QMap<int, NodeItem*>::iterator iter = _nodeItems.begin(); iter!=_nodeItems.end();)
-	{
-		if(!iter.value()->isVisible())
-		{
-			for(int i=0; i<_highlightedNodes.size(); ++i)
-			{
-				if(_highlightedNodes[i].second && _highlightedNodes[i].second == iter.value())
-				{
-					_highlightedNodes[i].second = nullptr;
-				}
-			}
-
-			delete iter.value();
-			iter = _nodeItems.erase(iter);
-		}
-		else
-		{
-			iter.value()->setVisible(_nodeVisible);
-			++iter;
-		}
-	}
+	removed = 0;
+	int visible = 0;
 	for(QMultiMap<int, LinkItem*>::iterator iter = _linkItems.begin(); iter!=_linkItems.end();)
 	{
 		if(!iter.value()->isVisible())
 		{
 			delete iter.value();
 			iter = _linkItems.erase(iter);
+			++removed;
 		}
 		else
 		{
 			++iter;
+			++visible;
 		}
 	}
-
+	UDEBUG("Links removed=%d, visible=%d", removed, visible);
 	if(_nodeItems.size())
 	{
 		(--_nodeItems.end()).value()->setColor(_nodeOdomCacheColor);
 	}
-
-	this->scene()->setSceneRect(this->scene()->itemsBoundingRect());  // Re-shrink the scene to it's bounding contents
-
-	if(!odomCacheIds.empty())
-		_odomCacheOverlay->setRect(this->scene()->itemsBoundingRect());
-	else
-		_odomCacheOverlay->setRect(0, 0, 0, 0);
-
+	
 	if(wasEmpty)
 	{
-		QRectF rect = this->scene()->itemsBoundingRect();
+		QRectF rect = this->scene()->sceneRect();
 		this->fitInView(rect.adjusted(-rect.width()/2.0f, -rect.height()/2.0f, rect.width()/2.0f, rect.height()/2.0f), Qt::KeepAspectRatio);
 	}

-	_graphRoot->setVisible(wasVisible);
-
 	UDEBUG("_nodeItems=%d, _linkItems=%d, timer=%fs", _nodeItems.size(), _linkItems.size(), timer.ticks());
 }

 void GraphViewer::updateGTGraph(const std::map<int, Transform> & poses)
 {
+	if(!_gtGraphRoot->isVisible())
+	{
+		UDEBUG("Ignoring updating gt graph, the graph root is not visible.");
+		return;
+	}
+
 	UTimer timer;
-	bool wasVisible = _gtGraphRoot->isVisible();
-	_gtGraphRoot->show();
-	bool wasEmpty = _gtNodeItems.size() == 0 && _gtLinkItems.size() == 0;
 	UDEBUG("poses=%d", (int)poses.size());
 	//Hide nodes and links
 	for(QMap<int, NodeItem*>::iterator iter = _gtNodeItems.begin(); iter!=_gtNodeItems.end(); ++iter)
@@ -811,23 +838,26 @@ void GraphViewer::updateGTGraph(const std::map<int, Transform> & poses)
 	{
 		if(!iter->second.isNull())
 		{
-			QMap<int, NodeItem*>::iterator itemIter = _gtNodeItems.find(iter->first);
-			if(itemIter != _gtNodeItems.end())
+			if(_nodeVisible)
 			{
-				itemIter.value()->setPose(iter->second, _viewPlane);
-				itemIter.value()->show();
-			}
-			else
-			{
-				// create node item
-				const Transform & pose = iter->second;
-				NodeItem * item = new NodeItem(iter->first, -1, pose, _nodeRadius, -1, _viewPlane, _linkWidth);
-				this->scene()->addItem(item);
-				item->setZValue(20);
-				item->setColor(_gtPathColor);
-				item->setParentItem(_gtGraphRoot);
-				item->setVisible(_nodeVisible);
-				_gtNodeItems.insert(iter->first, item);
+				QMap<int, NodeItem*>::iterator itemIter = _gtNodeItems.find(iter->first);
+				if(itemIter != _gtNodeItems.end())
+				{
+					itemIter.value()->setPose(iter->second, _viewPlane);
+					itemIter.value()->show();
+				}
+				else
+				{
+					// create node item
+					const Transform & pose = iter->second;
+					NodeItem * item = new NodeItem(iter->first, -1, pose, _nodeRadius, -1, _viewPlane, _linkWidth);
+					this->scene()->addItem(item);
+					item->setZValue(20);
+					item->setColor(_gtPathColor);
+					item->setParentItem(_gtGraphRoot);
+					item->setVisible(_nodeVisible);
+					_gtNodeItems.insert(iter->first, item);
+				}
 			}

 			if(iter!=poses.begin())
@@ -913,20 +943,6 @@ void GraphViewer::updateGTGraph(const std::map<int, Transform> & poses)
 			++iter;
 		}
 	}
-
-	if(_gtNodeItems.size() || _gtLinkItems.size())
-	{
-		this->scene()->setSceneRect(this->scene()->itemsBoundingRect());  // Re-shrink the scene to it's bounding contents
-
-		if(wasEmpty)
-		{
-			QRectF rect = this->scene()->itemsBoundingRect();
-			this->fitInView(rect.adjusted(-rect.width()/2.0f, -rect.height()/2.0f, rect.width()/2.0f, rect.height()/2.0f), Qt::KeepAspectRatio);
-		}
-	}
-
-	_gtGraphRoot->setVisible(wasVisible);
-
 	UDEBUG("_gtNodeItems=%d, _gtLinkItems=%d timer=%fs", _gtNodeItems.size(), _gtLinkItems.size(), timer.ticks());
 }

@@ -934,10 +950,11 @@ void GraphViewer::updateGPSGraph(
 		const std::map<int, Transform> & poses,
 		const std::map<int, GPS> & gpsValues)
 {
+	if(!_gpsGraphRoot->isVisible()) {
+		UDEBUG("Ignoring updating gps graph, the graph root is not visible.");
+		return;
+	}
 	UTimer timer;
-	bool wasVisible = _gpsGraphRoot->isVisible();
-	_gpsGraphRoot->show();
-	bool wasEmpty = _gpsNodeItems.size() == 0 && _gpsNodeItems.size() == 0;
 	UDEBUG("poses=%d", (int)poses.size());
 	//Hide nodes and links
 	for(QMap<int, NodeItem*>::iterator iter = _gpsNodeItems.begin(); iter!=_gpsNodeItems.end(); ++iter)
@@ -954,24 +971,27 @@ void GraphViewer::updateGPSGraph(
 	{
 		if(!iter->second.isNull())
 		{
-			QMap<int, NodeItem*>::iterator itemIter = _gpsNodeItems.find(iter->first);
-			if(itemIter != _gpsNodeItems.end())
+			if(_nodeVisible)
 			{
-				itemIter.value()->setPose(iter->second, _viewPlane);
-				itemIter.value()->show();
-			}
-			else
-			{
-				// create node item
-				const Transform & pose = iter->second;
-				UASSERT(gpsValues.find(iter->first) != gpsValues.end());
-				NodeItem * item = new NodeGPSItem(iter->first, -1, pose, _nodeRadius, gpsValues.at(iter->first), _viewPlane, _linkWidth);
-				this->scene()->addItem(item);
-				item->setZValue(20);
-				item->setColor(_gpsPathColor);
-				item->setParentItem(_gpsGraphRoot);
-				item->setVisible(_nodeVisible);
-				_gpsNodeItems.insert(iter->first, item);
+				QMap<int, NodeItem*>::iterator itemIter = _gpsNodeItems.find(iter->first);
+				if(itemIter != _gpsNodeItems.end())
+				{
+					itemIter.value()->setPose(iter->second, _viewPlane);
+					itemIter.value()->show();
+				}
+				else
+				{
+					// create node item
+					const Transform & pose = iter->second;
+					UASSERT(gpsValues.find(iter->first) != gpsValues.end());
+					NodeItem * item = new NodeGPSItem(iter->first, -1, pose, _nodeRadius, gpsValues.at(iter->first), _viewPlane, _linkWidth);
+					this->scene()->addItem(item);
+					item->setZValue(20);
+					item->setColor(_gpsPathColor);
+					item->setParentItem(_gpsGraphRoot);
+					item->setVisible(_nodeVisible);
+					_gpsNodeItems.insert(iter->first, item);
+				}
 			}

 			if(iter!=poses.begin())
@@ -1043,20 +1063,6 @@ void GraphViewer::updateGPSGraph(
 			++iter;
 		}
 	}
-
-	if(_gpsNodeItems.size() || _gpsLinkItems.size())
-	{
-		this->scene()->setSceneRect(this->scene()->itemsBoundingRect());  // Re-shrink the scene to it's bounding contents
-
-		if(wasEmpty)
-		{
-			QRectF rect = this->scene()->itemsBoundingRect();
-			this->fitInView(rect.adjusted(-rect.width()/2.0f, -rect.height()/2.0f, rect.width()/2.0f, rect.height()/2.0f), Qt::KeepAspectRatio);
-		}
-	}
-
-	_gpsGraphRoot->setVisible(wasVisible);
-
 	UDEBUG("_gpsNodeItems=%d, _gpsLinkItems=%d timer=%fs", _gpsNodeItems.size(), _gpsLinkItems.size(), timer.ticks());
 }

@@ -1085,6 +1091,7 @@ void GraphViewer::updateMap(const cv::Mat & map8U, float resolution, float xMin,
 	UASSERT(map8U.empty() || (!map8U.empty() && resolution > 0.0f));
 	if(!map8U.empty())
 	{
+		bool wasEmpty = _nodeItems.size() <= 1 && _linkItems.size() == 0 && _gridMap->pixmap().isNull();
 		_gridCellSize = resolution;
 		QImage image = uCvMat2QImage(map8U, false);
 		_gridMap->resetTransform();
@@ -1092,8 +1099,11 @@ void GraphViewer::updateMap(const cv::Mat & map8U, float resolution, float xMin,
 		_gridMap->setRotation(90);
 		_gridMap->setPixmap(QPixmap::fromImage(image));
 		_gridMap->setPos(-yMin*100.0f, -xMin*100.0f);
-		// Re-shrink the scene to it's bounding contents
-		this->scene()->setSceneRect(this->scene()->itemsBoundingRect());
+
+		if(wasEmpty)
+		{
+			this->fitInView(this->scene()->sceneRect(), Qt::KeepAspectRatio);
+		}
 	}
 	else
 	{
@@ -1186,10 +1196,10 @@ void GraphViewer::updateNodeColorByValue(
 			}
 		}
 	}
-	else if(min < max) {
+	else if(min >= max) {
 		UWARN("min (%f) is not less than max (%f), cannot change color of the graph.", min, max);
 	}
-	else if(hueMin < hueMax) {
+	else if(hueMin >= hueMax) {
 		UWARN("Hue min (%d) is not less than hue max (%d), cannot change color of the graph. The hue values should be set between 0 (red) and 360(pink).", (int)hueMin, (int)hueMax);
 	}
 }
@@ -1260,6 +1270,11 @@ void GraphViewer::setNodeInfo(int id, const QString & info)
 void GraphViewer::setLocalRadius(float radius)
 {
 	_localRadius->setRect(-radius*100, -radius*100, radius*200, radius*200);
+	if(_nodeItems.empty() && _linkItems.empty() && _gridMap->pixmap().isNull())
+	{
+		QRectF rect = this->scene()->sceneRect();
+		this->fitInView(rect.adjusted(-rect.width()/2.0f, -rect.height()/2.0f, rect.width()/2.0f, rect.height()/2.0f), Qt::KeepAspectRatio);
+	}
 }

 void GraphViewer::updateLocalPath(const std::vector<int> & localPath)
@@ -1384,14 +1399,17 @@ void GraphViewer::clearGraph()
 	_worldMapRotation = 0.0f;
 	_referential->resetTransform();
 	_localRadius->resetTransform();
-	this->scene()->setSceneRect(this->scene()->itemsBoundingRect());  // Re-shrink the scene to it's bounding contents
 }

 void GraphViewer::clearMap()
 {
-	_gridMap->setPixmap(QPixmap());
 	_gridCellSize = 0.0f;
-	this->scene()->setSceneRect(this->scene()->itemsBoundingRect());  // Re-shrink the scene to it's bounding contents
+	if(_gridMap->pixmap().isNull())
+	{
+		// there is no grid map, just return
+		return;
+	}
+	_gridMap->setPixmap(QPixmap());
 }

 void GraphViewer::clearPosterior()
@@ -1411,6 +1429,14 @@ void GraphViewer::clearAll()
 {
 	clearMap();
 	clearGraph();
+
+	// The only way to re-shrink the dynamic scene rect is to re-create the QGraphicsScene.
+	QSettings tmp;
+	saveSettings(tmp);
+	QRectF localRadiusRectF = _localRadius->rect();
+	setupGraphicsScene(); 
+	loadSettings(tmp); // restore previous state
+	_localRadius->setRect(localRadiusRectF);
 }

 void GraphViewer::saveSettings(QSettings & settings, const QString & group) const
@@ -1447,8 +1473,9 @@ void GraphViewer::saveSettings(QSettings & settings, const QString & group) cons
 	settings.setValue("referential_visible", this->isReferentialVisible());
 	settings.setValue("local_radius_visible", this->isLocalRadiusVisible());
 	settings.setValue("loop_closure_outlier_thr", this->getLoopClosureOutlierThr());
-	settings.setValue("max_link_length", this->getMaxLinkLength());
+	settings.setValue("min_link_length", this->getMinLinkLength());
 	settings.setValue("graph_visible", this->isGraphVisible());
+	settings.setValue("node_visible", this->isNodeVisible());
 	settings.setValue("global_path_visible", this->isGlobalPathVisible());
 	settings.setValue("local_path_visible", this->isLocalPathVisible());
 	settings.setValue("gt_graph_visible", this->isGtGraphVisible());
@@ -1497,8 +1524,9 @@ void GraphViewer::loadSettings(QSettings & settings, const QString & group)
 	this->setLocalRadiusVisible(settings.value("local_radius_visible", this->isLocalRadiusVisible()).toBool());
 	this->setIntraInterSessionColorsEnabled(settings.value("intra_inter_session_colors_enabled", this->isIntraInterSessionColorsEnabled()).toBool());
 	this->setLoopClosureOutlierThr(settings.value("loop_closure_outlier_thr", this->getLoopClosureOutlierThr()).toDouble());
-	this->setMaxLinkLength(settings.value("max_link_length", this->getMaxLinkLength()).toDouble());
+	this->setMinLinkLength(settings.value("min_link_length", this->getMinLinkLength()).toDouble());
 	this->setGraphVisible(settings.value("graph_visible", this->isGraphVisible()).toBool());
+	this->setNodeVisible(settings.value("node_visible", this->isNodeVisible()).toBool());
 	this->setGlobalPathVisible(settings.value("global_path_visible", this->isGlobalPathVisible()).toBool());
 	this->setLocalPathVisible(settings.value("local_path_visible", this->isLocalPathVisible()).toBool());
 	this->setGtGraphVisible(settings.value("gt_graph_visible", this->isGtGraphVisible()).toBool());
@@ -1533,6 +1561,10 @@ bool GraphViewer::isGraphVisible() const
 {
 	return _graphRoot->isVisible();
 }
+bool GraphViewer::isNodeVisible() const
+{
+	return _nodeVisible;
+}
 bool GraphViewer::isGlobalPathVisible() const
 {
 	return _globalPathRoot->isVisible();
@@ -1855,9 +1887,9 @@ void GraphViewer::setLoopClosureOutlierThr(float value)
 {
 	_loopClosureOutlierThr = value;
 }
-void GraphViewer::setMaxLinkLength(float value)
+void GraphViewer::setMinLinkLength(float value)
 {
-	_maxLinkLength = value;
+	_minLinkLength = value;
 }
 void GraphViewer::setGraphVisible(bool visible)
 {
@@ -1898,10 +1930,6 @@ void GraphViewer::setOrientationENU(bool enabled)
 	QTransform t;
 	t.rotateRadians(_worldMapRotation);
 	_root->setTransform(t);
-	if(_nodeItems.size() || _linkItems.size())
-	{
-		this->scene()->setSceneRect(this->scene()->itemsBoundingRect());  // Re-shrink the scene to it's bounding contents
-	}
 }

 void GraphViewer::setViewPlane(ViewPlane plane)
@@ -1928,11 +1956,6 @@ void GraphViewer::setViewPlane(ViewPlane plane)
 	_referentialXY->setVisible(plane==XY);
 	_referentialXZ->setVisible(plane==XZ);
 	_referentialYZ->setVisible(plane==YZ);
-
-	if(_nodeItems.size() || _linkItems.size())
-	{
-		this->scene()->setSceneRect(this->scene()->itemsBoundingRect());  // Re-shrink the scene to it's bounding contents
-	}
 }
 void GraphViewer::setEnsureFrameVisible(bool visible)
 {
@@ -2123,7 +2146,7 @@ void GraphViewer::contextMenuEvent(QContextMenuEvent * event)
 	menu.addSeparator();
 	QAction * aSetNodeSize = menu.addAction(tr("Set node radius..."));
 	QAction * aSetLinkSize = menu.addAction(tr("Set link width..."));
-	QAction * aChangeMaxLinkLength = menu.addAction(tr("Set maximum link length..."));
+	QAction * aChangeMinLinkLength = menu.addAction(tr("Set minimum link length..."));
 	menu.addSeparator();
 	QAction * aEnsureFrameVisible;
 	QAction * aShowHideGridMap;
@@ -2241,12 +2264,12 @@ void GraphViewer::contextMenuEvent(QContextMenuEvent * event)
 	aMouseTracking->setCheckable(true);
 	aMouseTracking->setChecked(_mouseTracking);
 	aMouseTracking->setEnabled(_viewPlane == XY);
-	aShowHideGraph->setEnabled(_nodeItems.size() && _viewPlane == XY);
-	aShowHideGraphNodes->setEnabled(_nodeItems.size() && _graphRoot->isVisible());
+	aShowHideGraph->setEnabled(_viewPlane == XY);
+	aShowHideGraphNodes->setEnabled(_graphRoot->isVisible());
 	aShowHideGlobalPath->setEnabled(_globalPathLinkItems.size());
 	aShowHideLocalPath->setEnabled(_localPathLinkItems.size());
-	aShowHideGtGraph->setEnabled(_gtNodeItems.size());
-	aShowHideGPSGraph->setEnabled(_gpsNodeItems.size());
+	aShowHideGtGraph->setEnabled(_gtGraphRoot->isVisible());
+	aShowHideGPSGraph->setEnabled(_gpsGraphRoot->isVisible());
 	aShowHideOdomCacheOverlay->setEnabled(_odomCacheOverlay->rect().width()>0);

 	QMenu * viewPlaneMenu = menu.addMenu("View Plane...");
@@ -2363,8 +2386,7 @@ void GraphViewer::contextMenuEvent(QContextMenuEvent * event)

 				//reset scale
 				_root->setScale(1.0f);
-				this->scene()->setSceneRect(this->scene()->itemsBoundingRect());  // Re-shrink the scene to it's bounding contents
-
+				this->scene()->setSceneRect(QRectF());

 				QDesktopServices::openUrl(QUrl::fromLocalFile(filePath));
 			}
@@ -2426,13 +2448,13 @@ void GraphViewer::contextMenuEvent(QContextMenuEvent * event)
 			setLoopClosureOutlierThr(value);
 		}
 	}
-	else if(r == aChangeMaxLinkLength)
+	else if(r == aChangeMinLinkLength)
 	{
 		bool ok;
-		double value = QInputDialog::getDouble(this, tr("Maximum link length to be shown"), tr("Value (m)"), _maxLinkLength, 0.0, 1000.0, 3, &ok);
+		double value = QInputDialog::getDouble(this, tr("Minimum link length to be shown"), tr("Value (m)"), _minLinkLength, 0.0, 1000.0, 3, &ok);
 		if(ok)
 		{
-			setMaxLinkLength(value);
+			setMinLinkLength(value);
 		}
 	}
 	else if(r == aChangeNodeColor ||