# helical Geometry¶

The following documentation has been extracted automatically from the comments found in the source code. Discard Parameters. object variable.

class Parameters_module.Parameters

The input variables are read from the input file. The input file is written with python syntax. The Input file is interpreted as python after a preprocessing The preprocessing was introduced at the time of HST-> PYHST transition to maintaing compatibility with:

• NO/YES meaning 0/1

• items containing FILE in their name can be initialized without using the “” which are otherwise necessary for strings

The input file has to set (some of) the following variables. To setup easily an input file you are suggested to start from one of the examples given in the doc.

DXPERPROJ = 0.0

Set this parameter is the translation is not parallel to the rotation axis. Units are pixels per projection.

DZPERPROJ = 0.0

If this parameter is different from zero, the helicoidal scan reconstruction is activated. A positive DZPERPROJ means that the rotation axis is going down. In other words the detector is going up respect to the axis.

Units are pixels per projection.