PITCH to Curve radius

I am working on a utility to produce smooth verticle transition curves. That is when going from a pitch of 0 to a pitch or (for example) 5 you would get a curved piece of track so that the change is not abrupt. What I need is a way to convert the change in PITCH to a curve radius. Is there an easy ( of complex) way to do this. I want to input the change in pitch and get the appropiate curved piece.

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RE: PITCH to Curve radius, R36 9346, Feb-03-04, 01:45 PM, (1) RE: PITCH to Curve radius, ferrovipathe, Feb-03-04, 01:52 PM, (2) RE: PITCH to Curve radius, smace, Feb-03-04, 07:11 PM, (4) RE: PITCH to Curve radius, ferrovipathe, Feb-04-04, 05:18 AM, (5) RE: PITCH to Curve radius, Simon_G, Feb-04-04, 03:01 PM, (7) RE: PITCH to Curve radius, Simon_G, Feb-04-04, 03:03 PM, (8) RE: PITCH to Curve radius, smace, Feb-04-04, 08:02 PM, (9) RE: PITCH to Curve radius, smikes, Feb-03-04, 02:03 PM, (3) RE: PITCH to Curve radius, Stooopid_person, Feb-04-04, 06:36 AM, (6)

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That's a complicated task because you have to figure in both the grade change and the lateral curve radius as well! -Robert Marrero

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Sorry, but I don't think it is possible to do that with BVE.
If it is possible to put an object (freeobject) meter by meter, other commands works well only every 25 m.
So, when you create a curve, you begin with:
1000 curve(0) pitch(0)
1025 curve(1000) pitch(5),
and BVE is supposed to smooth everything.
If you want to be more realist, as I know, the only way is some think like that:
1000 curve(0) pitch(0)
1025 curve(5000) pitch(1)
1050 curve(2500) pitch(3)
1075 curve(1000) pitch(5)If you create a complex curved track with verticle transition, I am afraid that BVE don't care. If you use a wall(or a road, a river,..) as track, train (or car, plane, ship) run on it as on rails. The rail object is a visual object, and curve and pitch commands are not.
They teach BVE how it must turn and pitch track whatever the rail object, even if this one is invisible.All the best.

http://ferrovipathe.free.fr

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>
>If you create a complex curved track with verticle
>transition, I am afraid that BVE don't care. If you use a
>wall(or a road, a river,..) as track, train (or car, plane,
>ship) run on it as on rails. The rail object is a visual
>object, and curve and pitch commands are not.
That is what I am producing, a visual object. I know that BVE smooths the verticle transition already. What I want is the smooth visual object. I can already make the object,the attached screen shot shows a left hand curve that drops down. The dropdown is fairly smooth. Looks better when running the line. What I need is the numbers to make it match the change in pitch commands. I had to guess to make this one and it is not quite correct.

Attachments

http://www.train-sim.com/dcforum/User_files/402038a11efc278d.jpg

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>That is what I am producing, a visual object. I know that
>BVE smooths the verticle transition already. What I want is
>the smooth visual object. I can already make the object,the
>attached screen shot shows a left hand curve that drops
>down. The dropdown is fairly smooth. Looks better when
>running the line. What I need is the numbers to make it
>match the change in pitch commands. I had to guess to make
>this one and it is not quite correct.
OK !The only way is to create a curved track with (I don't remember the English word) a bump on Y in the middle.If your track have five segments, it is easy:
X Y Z
1 - 0 0 0
2 - .. 1 5
3 - .. 2 10
4 - .. 2 15
5 - .. 1 20
6 - 0 0 25And you put your freeobject like a track, with pitch before and after as in usual way. BVE smooth pitch, and your object smooth the visual effect.All the best.

http://ferrovipathe.free.fr

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If it helps, the vertical radius is given byr = 2Lnwhere L is as shown on the first diagram below and n is the gradient change expressed as '1 in n'. Using BVE pitch, this becomesr = 2L*1000/pwhere p is the change in pitch.The second diagram shows how you would use this in BVE, with the red lines representing the 'flat' rail sections and the blue line your curved rail object. You split the pitch change in two, before and after your curved rail object, but you calculate the radius using the complete pitch change asr = 25 * 1000 / p(Note that the angle in the diagram is exaggerated and L=12.5m to a very good approximation for all the pitch changes we're likely to need.)Now you just need to convert the radius into y-offsets!Cheers
Simon

Attachments

http://www.train-sim.com/dcforum/User_files/40214cf369bf926f.gif

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Lost me second diagram for some reason:

Attachments

http://www.train-sim.com/dcforum/User_files/40214ffb02391564.gif

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Thank you, that was what I was looking for. The utility spreadsheet exists and works now using a Vert radius expressed in meters. Now I need to add your formula and make the appropiate changes in the sheet and try it somemore. If all goes well, should be available this or next week end.

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LAST EDITED ON Feb-03-04 AT 02:05 PM (EST)

How would the program recognize the curved piece and follow the gradual change in pitch of the curve?Sorry didn't see previous reply

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>How would the program recognize the curved piece and follow
>the gradual change in pitch of the curve?Sorry didn't see
>previous reply The program already has smooth curves and pitches! The curves is more obvious, so if you drive an older line with sharp curve, like the Bakerloo Line, you will find the train doesn't follow the track on curves!

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