diff --git a/guilib/src/DatabaseViewer.cpp b/guilib/src/DatabaseViewer.cpp
index a6ee4c10..804756e5 100644
--- a/guilib/src/DatabaseViewer.cpp
+++ b/guilib/src/DatabaseViewer.cpp
@@ -31,6 +31,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <QMessageBox>
 #include <QFileDialog>
 #include <QInputDialog>
+#include <QDesktopWidget>
 #include <QGraphicsLineItem>
 #include <QtGui/QCloseEvent>
 #include <QGraphicsOpacityEffect>
@@ -1735,13 +1736,15 @@ void DatabaseViewer::view3DMap()
 				QDialog * window = new QDialog(this, Qt::Window);
 				window->setModal(this->isModal());
 				window->setWindowTitle(tr("3D Map"));
-				window->setMinimumWidth(800);
-				window->setMinimumHeight(600);
+				window->setMinimumWidth(120);
+				window->setMinimumHeight(90);
+				window->resize(QDesktopWidget().availableGeometry(this).size() * 0.7);
 
 				rtabmap::CloudViewer * viewer = new rtabmap::CloudViewer(window);
 
 				QVBoxLayout *layout = new QVBoxLayout();
 				layout->addWidget(viewer);
+				layout->setContentsMargins(0,0,0,0);
 				viewer->setCameraLockZ(false);
 				window->setLayout(layout);
 				connect(window, SIGNAL(finished(int)), viewer, SLOT(clear()));
diff --git a/guilib/src/ExportCloudsDialog.cpp b/guilib/src/ExportCloudsDialog.cpp
index f035d7aa..46a1ac8c 100644
--- a/guilib/src/ExportCloudsDialog.cpp
+++ b/guilib/src/ExportCloudsDialog.cpp
@@ -57,6 +57,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <QMessageBox>
 #include <QFileDialog>
 #include <QInputDialog>
+#include <QDesktopWidget>
 
 namespace rtabmap {
 
@@ -524,8 +525,9 @@ void ExportCloudsDialog::viewClouds(
 		{
 			window->setWindowTitle(tr("Clouds (%1 nodes)").arg(clouds.size()));
 		}
-		window->setMinimumWidth(800);
-		window->setMinimumHeight(600);
+		window->setMinimumWidth(120);
+		window->setMinimumHeight(90);
+		window->resize(QDesktopWidget().availableGeometry(this).size() * 0.7);
 
 		CloudViewer * viewer = new CloudViewer(window);
 		viewer->setCameraLockZ(false);
@@ -536,6 +538,7 @@ void ExportCloudsDialog::viewClouds(
 
 		QVBoxLayout *layout = new QVBoxLayout();
 		layout->addWidget(viewer);
+		layout->setContentsMargins(0,0,0,0);
 		window->setLayout(layout);
 		connect(window, SIGNAL(finished(int)), viewer, SLOT(clear()));