Chapter 2. MegaPOV References
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## Chapter 2. MegaPOV References

## 2.1. Options

### 2.1.1. `Frame_Step`

### Włodzimierz ABX Skiba

The `Frame_Step`=`n` (`+STP` `n`) option introduces breaks in the order of rendered steps. It splits the order of rendered frames into a 'virtual' and a 'real' order.

'Virtual' order is the same as the traditional (used in POV-Ray™ 3.5) order described with `Initial_Frame`, `Final_Frame`, `Initial_Clock`, `Final_Clock`, `Subset_Start_Frame`, `Subset_End_Frame`. This order is what the scripts reads from `initial_frame`, `clock_delta` and other animation related build-in tokens in SDL.

'Real' order is a subset of 'virtual' order. It is every n-th frame where n is the value of `Frame_Step`. Selected frames are reordered (with ascending or descending order) according to the sign of `Frame_Step` option.

`Frame_Step` is supposed to use parallel rendering over one source with one location shared between instances of renderer.

Example 2.1. Influence of `Frame_Step` on generated files

The following command line:

    megapov +Iscene.pov Initial_Frame=1 Final_Frame=5 +FN

causes the creation of files in such order:

    scene1.png
    scene2.png
    scene3.png
    scene4.png
    scene5.png

while when using `Frame_Step`:

    megapov +Iscene.pov Initial_Frame=1 Final_Frame=5 +FN Frame_Step=-2

causes a subset of it in the following order:

    scene5.png
    scene3.png
    scene1.png

| Important
`Frame_Step` different than `1` works fine for those animations where variables are not passed between frames when using external files and where the next frame does not use values derived from a previous (in the meaning of virtual order) frame by other ways.

### 2.1.2. HDR (High Dynamic Range) image output

### Christoph Hormann

Apart from reading HDR images as image maps (see Section 2.6.6, “HDR (High Dynamic Range) image type”) MegaPOV also supports this file format for image output. Further information on this file format can be found in Section 2.6.6, “HDR (High Dynamic Range) image type” as well.

The file format identification character is `H`. Writing this file format is activated by the command line option

    +FH

or the ini option

    Output_File_Type=H

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1.5. Where do I find MegaPOV? | Home | 2.2. Expressions