Graphics Applications For Stand-alone Drive Multi-channel Projection System Transplantation And Rendering Techniques

Graphics applications with high resolution are widely used in our daily life.To display such applications,we can use high definition LCD Panel or plasma panel display.However,these displays offer limited size of screen due to the limitation of physics.Compare with other devices which support high resolution output and offers large sized display,multi-channel projector-based display wall system driven by a single PC is affordable and easy to manage.The output of multi-channel display system must be corrected.In obtaining parameters for geometry correction and color correction,existing techniques are too complex and inefficient.With the correction parameters,existing techniques migrate the applications by screen copy APIs provided by the operating system,which suffers from following disadvantages.First,for graphics applications,after the migration the frame rate is low and the output image flickers.Second,since the projectors are only allowed to use half of the output pixels of the graphics card,the number of projector-channels in the system is less than the number of output channels of the graphics card.Finally,for operating systems with 3D desktop,the outputs of two dimensional applications are combined by a graphics application,which further limits the usage of the technique.In this paper,we propose one more efficient and effective approach in application migration and image correction.Since usually the number of projectors in our system is modest,we use an efficient method for geometry correction.For photometric correction,we propose a simpler and more efficient method based on the RAW format of commercial digital camera.Experimental result shows that,while the existing method for ITF recovery requires tens of thousands of photographs,our method only requires tens.For application migration,we propose one function interception based approach to overcome the limitations of previous technique.With the combination of two existing techniques of function interception(DLL replacement and Detours),the correction is applied before the running of graphics application,so that every frame can be corrected.Besides,the work of the development of the intercepting library is reduced. By intercepting the calls from application to the screen update function within graphics library during runtime,the correction is applied without modification to the source code of graphics application.Since the correction brings no contention with the graphics application,the applications do not flicker after migration.Since the correction directly modifies the frame buffer of the application,all pixels are available to projectors within the system.Therefore,the system can support more projector channels with our approach for applications running in full-screen mode.Experimental result shows that,after the application of our function interception based migration approach,the rendering of the application is smooth.Compared with screen copy based approach,the frame rate is 1.4 times for graphics applications.In operating system with 3D desktop,the frame rate is 2.5 times for common 2D applications.