Interactive 3D graphics in HEP

Transcription

1 12/07/18 1

2 Interactive 3D graphics in HEP Interactive 3D data visualization plays a key role in all HEP experiments, as it is used in many tasks at different levels of the data chain: Detector development / geometry studies Check the detector simulation Investigate and debug the alignment Verify and debug reconstruction algorithms Explore single events to double-check the event selections of a physics analysis Visually inspect problematic measurements/ events/cuts/algorithms Visually verify that the data taking is fine, by looking at the detector s measurements 12/07/18 ATLASrift team, CHEP

3 Visualisation in HEP HEP has a long tradition in building tools to interactively visualize data Sometimes, those tools use OpenGL calls directly, to keep the max freedom in graphics manipulation. But, most of the time, they 1 use 3 rd parties graphics libraries, which offer higher level shapes, tools, and routines 1 9 to conveniently build 3D scenes from source code (C++, Java, Javascript,.) 9 8 The use of a graphics library offers the 7 2 greatest flexibility, because they can be easily integrated in an existing code base. 9 However, they often offer only basic functionalities in terms of graphics rendering 12/07/18 ATLASrift team, CHEP

4 Game Engines In the gaming industry, games are developed by choosing two main roads: by the usage of native calls (OpenGL/DirectX) or by using a game engine. A game engine is a development space featuring and IDE, a compiler, a debugger, together with a complete set of graphics tools, UI libraries and rendering engines. The development of the game is done inside the engine, which then builds and packages the final application. Game engines usually offer really optimised libraries and tools (especially those that are used to build commercial games), at the cost of a limited freedom. Two game engines play a leading role on today s market: Unity and Unreal Engine. Both of them are free to use, non-commercial purpose and small indie projects. Unity is told to be easier to learn, but the development is based on C# Unreal Engine is harder to grasp, but the development is based on C++, which makes it easier for HEP developers. It is open source. 12/07/18 ATLASrift team, CHEP

5 Using external graphics libraries Using game engines graphics library application source code Game Engine user s source code graphics library compiler compiler application application 12/07/18 ATLASrift team, CHEP

6 How it all started, in 2015 Bringing HEP event viewers into the future A Virtual Reality application that provides an interactive, immersive visit to the ATLAS experiment. One can learn about the experiment as a whole, inspect individual sub-detectors, view real interactions, or take a scripted walkthrough explaining questions physicists are trying to answer. 12/07/18 ATLASrift team, CHEP

7 Goals/target audiences - 1 An education and outreach tool for the 21st century 7

8 Goals/target audiences - 2 The Grand Plan We want that any HEP experiment can relatively easily make an event viewer, that anybody, anywhere could start and use as easily as an Xbox video game, while providing all the tools a physicist may need. 8

9 Technology behind the scenes Development platform: Unreal Engine ATLAS geometry: is exported using the experiment s tools (VP1 event display program), then converted to 3D format (fbx) and simplified as needed. Caverns, corridors, supports: come from the CERN engineering CAD models (Catia). They were also simplified, reorganized, tessellated in Moi3D. A lot of other programs: are used to stich 4Pi images, to edit audio, to tessellate geometries, to fix meshes, to create surfaces, to import data into the Google Application Engine. Some of it developed in-house. 12/07/18 ATLASrift team, CHEP

10 Experiment menu Sub-detectors can be solid, semi-transparent, off Visitor can fly and cross surfaces In busy/claustrophobic areas 4 pi pictures are hocked as little balls to grab/open Auto-pilot commented tour for events ( multilingual ) 12/07/18 ATLASrift team, CHEP

11 Control room menu Display of the detector status and shifters live camera is not permitted by ATLAS policy So, turned to a data / computing / event display theme Real time live pages such as LHC page 1 and/or computing dashboards Data / computing / event display videos. Guided tour explaining the desks. 11

12 Globe virtual exhibit menu Ground floor: explaining sub detectors Wooden ramp: ATLAS history (25th anniversary) First floor: cinema, which will eventually be shared 12

13 Development: pros & cons During the development of ATLASrift, we acquired a fair experience on using UnrealEngines for HEP-based applications Game engines offer many advantages: Complete set of highly-optimized graphics tools/routines They build highly optimized stable code Powerful packaging system, able to cross-build for many different platforms (PC, Mac, VR, HTML5, stores ) Separation between design and functionalities in applications makes collaboration among different stakeholders (developers, designers) easier. But they also have important drawback in our opinion: the engine environment is strongly self-contained, and it is very hard to use external libraries. 12/07/18 ATLASrift team, CHEP

14 graphics library application source code compiler EASY! external library HARD Game Engine user s source code compiler graphics library application application 12/07/18 ATLASrift team, CHEP

15 What about event display? 12/07/18 ATLASrift team, CHEP

16 Difficulties Using of the graphics engine in current HEP code (as we do with Open Inventor, OSG and similar libraries) is impossible: User s code has to be embedded into the engine This makes development of smaller projects and/or games faster, but it is quite hard to work in a collaborative way: Unreal Engine packs code in container files, which are seen as BLOB by GitHub; one cannot compare files from the source code but by opening them in the engine. The engine only officially supports native compilers (MS Visual Studio on Windows and Xcode on Mac) Use of other compilers is difficult and tricky. 12/07/18 ATLASrift team, CHEP

17 Current solution To display event data, one must export them in a common data exchange format like JSON It is fine for static event displays (e.g. for public/press/outreach) = Target 1 But not yet a viable way for interactive data visualisation by scientists = Target 2 12/07/18 ATLASrift team, CHEP

18 Conclusions Game engines are extremely powerful tools to create visually engaging applications. Their graphics features, highly-optimized routines are wonderful!!! However, the access to traditional HEP datasets usually needs external libraries which are difficult to use from the engine. The temporary solution used in ATLASrift ( export events in a JSON file ) satisfies the first goal: outreach. More experiments of the kind and work is needed for the second: physicists interactive work. Client-server architectures to interact with data from outside the experiment s framework are under study, also in the context of the HSF Visualization working group HSF White Paper: //hepsoftwarefoundation.org/activities/cwp.html 12/07/18 ATLASrift team, CHEP

19 12/07/18 ATLASrift team, CHEP