The CMS Tracker has a complex spatial structure consisting of around 17000 modules(silicon micro-strip and pixel sensors) organized in 13 barrel cylinders and 14+14 end cap disks.
Graphical objects can be used to represent tracker information like:
What we have now
CMS has chosen to build a toolkit of visualization objects called Iguana, instead of a stand-alone monolithic program. This toolkit is already used to allow visualization in Orca and Oscar. The tracker is described as a OpenInventor scene with a graph of 17000 boxes each one corresponding to a single sensor.
The simulated signal in the detector is represented by a single set of points in space.
Simulated and reconstructed tracks are also represented in space(Fig).
In Iguana there are also the usual objects used for statistical analysis (histograms,scatter plots,...)
All this works inside Orca but has some problems,the principal one being the following:
The detector description requires too many computer resources (around 80Mb of central memory) that makes it almost unusable. For this reason it is also unthinkable to introduce greater detail in the 3D tracker description. On the other hand this 3D description is essential to understand the detector so:Our main goal is to build some 2D graphics objects to improve the performance of existing tracker data visualization tools in IGUANA. These graphics objects will be used also outside ORCA in a stand-alone program and in a web interface. These objects will be built using Iguana with the only probable exception of their implementation in a Web interface . They should improve the existing visualization performance by:
Why a stand alone program
We suggest in some cases the use of a stand-alone program because using ORCA has the following problems:
The solution is to make a stand-alone program which reads events created by ORCA and ready to be visualized . To share event data between CMS programs an XML format should be setup (like what we have already for the detector description). In this way, you don't need to use COBRA, Objectivity and similar stuff(expensive in terms of computer resources) when you want only to do some simple visualization.
Why a Web interface
Instead a web interface can be very useful when there is little interactivity, for example to display information in the tracker construction data base: prototype.
Four 2D objects
The main objects that we propose to build are the following:
A 2D graphical object to quickly select parts of the tracker (layers, rings, ...) : prototype. It's a schematic representation of a yz cross section. The user can select a single ring of the forward disks or barrel cylinders. Only the signal generated by the selected parts will be shown.
2D graphics object to select single modules(prototype);
2D graphics object that is a kind of "module map" used to display information about single modules coded in various ways.This object can be used to represent with greater detail tracker data at the level of the single sensor(for example fired strips,dead channels,etc).prototype
2D graphics object to represent the whole tracker(prototype). This is a map where one can represent quantities defined for each sensor coded in some way.
These are only suggestions and the main purpose of this presentation is to have your feedback in order to improve these objects making them really useful.