I have created the very simple rendering program based on one VTK examples that use QT GUI and VTK (Visualization Toolkit) for those who want to try QT+VTK programming. I used QT 4.6 and VTK 5.6 for this program.

This is just a small program written in C++ (OOP) style. This program create QT MainWindow and add the QVTK viewer widget for 3D rendering with VTK. It also has one simple QT GUI panel on the left side but I did not add any specific functionality to the buttons and controls. To design or modify the MainWindow and panel, we should use the QT designer that comes with QT. Those MainWindow and control panel UI are in SimpleVTK.UI and MainPanel.UI files respectively.  I also overlay a text sentence onto 3D rendering window using VTK functions. I feel that VTK is very nice to be used for visualization and 3D renderings. It can help us to manipulate the 3D processing, rendering and visualization tasks with its built-in classes. VTK is especially good for students and researchers for their projects. The good thing about VTK is that it is totally FREE and we can even build VTK libraries from source codes depends on our specific needs. By combining VTK with power GUI libraries such as QT, we can get very nice cross-platform application because QT is also FREE and open source.

This simple example program uses OOP style programming and also follows the programming styles of QT and VTK. Therefore, it might not be very easy to learn for those who are very new to programming but I believe that it should be OK after giving some time to learn it. We can add more functionalities such as loading OBJ model file and other processing capabilities based on VTK on this simple program. Adding the new menus and new GUI controls into this program should be done in QT designer because that will be the easiest way to do. We can of course add new menus and GUI controls at code level but using I strongly recommend to use QT Designer.

Link to download the simple QT+VTK program

You need to download and install QT 4 libraries and VTK 5.x libraries to run this program. You can also build QT and VTK libraries from source codes if you want. The good thing about building those libraries from source codes is you can configure them according to your needs. You also have to build them from source codes if you really want to get 64-bit (x64) versions. I also created CMakeLists files for this program therefore you can build the project for Windows, Linux or Mac OS X using CMAKE. You need to download and install CMAKE to generate the project for these source codes. Because QT and VTK are cross platform, this program is also a cross platform program.

I hope this simple program can help beginners who want to learn about creating rendering program with QT + VTK (and QVTK).

I tried to develop one visualization and 3D rendering program on Linux using VTK (Visualization Toolkit). My program was written by C/C++ programming language. I created that program as a cross-platform program to build and run on Windows, Linux and Mac OS X.

For GUI (Graphical User Interface), I used QT 4 libraries. I used VTK 5.6 for visualization purposes including 3D renderings. VTK is based on OpenGL for 3D renderings and transformations.  I wanted to add ability to free-hand draw on background image. Therefore, I used vtkImageTracerWidget to draw free-hand lines in front of background images. I had to set the projection plane, viewing vector and normal vector appropriately so that we could see the drawn line in front of background image. Otherwise, the line would appear behind the image and we could not see it although it was being drawn correctly. I could successfully set the normal vector and viewing vectors for vtkImageTracerWidget so that I could see the drawn line on background image.

I built the program and run on Windows and Mac OS X and everything was fine. However, when I built and run the same program on Linux OS, I could not see the free-hand line in front of the background image although I knew that the line was drawn actually. I could extract the points along the line after drawing although I could not see the line properly. I thought that I needed to set the projection plane and vectors correctly and I checked my codes thoroughly and I found that nothing was wrong in codes. I tried to build the exact codes on Windows again and run the program and I could see the line drawn by imageTracerWideget. Therefore, I believed that it was not because of programming codes.

I was using generic graphic drivers on Linux OS and I suspected that the graphic drivers might be problem at that point. I tried to update the graphic drivers for my ATI Radeon  HD graphic card on Linux. I used Linux Mint 11 (Genome) version and adding additional drivers was very easy on Linux Mint 11. The system could search the ATI’s propriety drivers automatically and updated for me. After that, I tried to run my program again and I could see the freehand line that was drawn by vtkImageTracerWidget. Therefore, I got a precious experience that the graphic card driver was also very important in doing 3D visualization and renderings.  If I insisted that the problem was inside my codes and if I tried to solve by changing settings and codes inside my problem, I might not be able to solve my problem with VTK.

I also encountered similar problem in playing one first person shooter (FPS) game on Windows a few years ago. Although the game was running very well, I could not see the cross-hair pointer to point the guns inside game. I tried to configure graphic settings and resolutions in various ways but I could not solve the problem. The graphic chip on that computer was Intel GMA and I finally downloaded and installed the latest released graphic drivers from Intel web site and everything was fine.

Therefore, it is sure that we need correct and probably latest released of graphic card drivers while working with graphic packages. I share this experience for those who are working with VTK or other similar graphic rendering packages to minimize the problem solving time. I hope this post is also useful for some developers.