Blender and Track Planning - An Experiment

[Anonymous]

Hi everyone,

I've been experimenting with using Blender (a free 3D modeling program) for a layout planner.  I've finished the basic lineup of O27 track so far.  It's no replacement for programs like RR-Track, as a certain proficiency with Blender helps.  Still, I think it'll be fun to eventually be able to render a whole layout complete even with trains if I feel like making them (hm, related idea - has anyone made digital models of Lionel trains?).  So just thought I'd share the pics with y'all and maybe get some feedback.  :)

On a related note, does anyone know the dimensions of Lionel O27 ties and the official distance they're supposed to be from the end of the rail?  I'll eventually be turning the simple bezier curve mockups into fully modeled pieces of track.

-Stefan-

[lionelsoni]

It looks from your pictures that you are using a radius of 13.5 inches--half of 27.  The 27 inches of O27 is actually to the outsides of the ties, which are just a hair under 2 inches long.  So the actual radius to the center rail is 12.5 inches.

The length of a straight O27 section is the radius divided by the square-root of 2, or 8.839 inches, which is often referred to approximately as 8 7/8 inches.

A pretty accurate technique for determining the radius of a curved piece of track is to measure the chord between the ends of the center rail.  The radius is

radius = (chord / 2) / sin(angle / 2)

where "angle" is the angle through which the curved piece turns, for example, 45 degrees for O27.  This method is not very sensitive to the exact curvature of the track piece.  It can be made even better by approximately subdividing the track and measuring multiple chords along the center rail.  Then average the chords and use the formula with angle divided by the number of chords used.  For example, measure and average two chords from the middle to the ends of a piece of 45-degree track and use angle = 22.5 degrees instead of 45 degrees.

[Anonymous]

Oh bugger and ow.

All that talk of chords hurts my head.  Should be simple enough to adjust the radius.  As for the length of the track - will the discrepancy be enough to mess with the geometry severely?

-Stefan-