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# 3.4.1.1 Projections User Guide

Two types of projected views are supported in Fireworks.They can have different configuration, but in the simplest case the following formula can be applied:

• RPhi, same as XY ortographic view :
```x_screen = x
y_screen = y
```

• RhoZ projection is not YZ projection even in the simplest case. Screen X coordinate presents Z coordinate and Y screen coordiante presents distance to center with a sign of Y coordinate:
```x_screen = z
y_screen = sqrt(x*x + y*y) * sgn(y)
```

Bellow is a screen shot of ROOT demo showing the simplest case of the 2D projections. In left most picture is a straight line and a geometry in 3D view. Next to it are shown the same elements in projected RPhi and RhoZ view.

## Distorted 2D projections

FishEye distortion is used to enlarge central region of detector. In the picture bellow are example of 2D projected views with distortion value of 3.

## Fixed Radius in distorted projections

Distortion can be locked above defined radius.If you compare this pictures with the one above you can see the outer layer of geometry is less distorted.

Original idea for the projections was taken from H. Drevermann article Can We See What We Want to See ?

Topic attachments
I Attachment History Action Size Date Who Comment
gif barrel_sta_muon.gif r1 manage 9.8 K 2008-08-17 - 23:14 DmytroKovalskyi barrel stand alone muon (CRUZET3)
png distUnlim.png r1 manage 57.2 K 2009-12-08 - 20:48 AljaMrakTadel distUnlim
png distLim.png r1 manage 55.5 K 2009-12-08 - 20:47 AljaMrakTadel fixedR
gif 62966_3274141.gif r1 manage 3.8 K 2008-10-03 - 17:20 DmytroKovalskyi Rho-Z view of a track with significant impact parameter
png simple.png r1 manage 55.7 K 2009-12-08 - 20:41 AljaMrakTadel Simple non-distorted projection
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Topic revision: r8 - 2010-12-14 - AljaMrakTadel

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