[Goku]

Quote

Please, SIR, try to be more precise in your phrasing; precision counts. A useful practice is to read what you've written before submitting it -- at least once. Now, I know you're not going to like that idea, but it will save you future time by reducing reader uncertainty.

I think that "one track shapes" can't mean one shape with multiple tracks. But my English isn't good, so ..

[WaltN]

Goku, on 09 September 2018 - 07:03 AM, said:

I think that "one track shapes" can't mean one shape with multiple tracks. But my English isn't good, so ..

A hyphen in between "one" and "track" would have made it clear.

[WaltN]

Chris and Dave,

I'll try to find the time this week to relate the roll angle (transverse to the track) to the arc length angle. And then factor in the rail height delta. Hope you have a calculator with trig functions.

[jtr1962]

WaltN, on 09 September 2018 - 07:02 AM, said:

What do you mean by "bank"? Aircraft-style bank, which is a roll? Or are you talking about grade (elevation change)? PRECISION!

I really meant superelevated, although banked means the same thing in the context of a curve. The bottom line though is the issue mentioned is avoided by using small track segments, albeit at the expense of MSTS compatibility.

[Genma Saotome]

jtr1962, on 09 September 2018 - 09:31 AM, said:

I really meant superelevated, although banked means the same thing in the context of a curve. The bottom line though is the issue mentioned is avoided by using small track segments, albeit at the expense of MSTS compatibility.

No. The issue is roughly solved with short segments and that can remain compatible. But let me put it into the traditional context: When you set down curve shapes on a grade the near end is parallel to the ground but the far end is "tipped". Repeat. The result is a slight bump on the outside rail because the segment you just added has the near end parallel to the ground and the section you just joined too is tipped on an angle The shorter the track segments, the lower the grade, the smaller the bump. Use large segments, higher grades, the larger the bump. Very, very short segments, you might not notice the bump outside of the cab view. This becomes even more of a problem if it happens to be multi-track shapes.

In some future environment things may remain exactly as described, except perhaps that long curved segments are not available -- so there is still a bump of some magnitude. Or, if things get sophisticated and the track you've laid actually has a cant built into it, with run in and run out sections, then it would be exactly as a rail engineer would have built... all very smooth. But having track with a built in cant might (would?) be problematic for both Open Rails and MSTS.

[jtr1962]

Genma Saotome, on 09 September 2018 - 11:51 AM, said:

No. The issue is roughly solved with short segments and that can remain compatible. But let me put it into the traditional context: When you set down curve shapes on a grade the near end is parallel to the ground but the far end is "tipped". Repeat. The result is a slight bump on the outside rail because the segment you just added has the near end parallel to the ground and the section you just joined too is tipped on an angle The shorter the track segments, the lower the grade, the smaller the bump. Use large segments, higher grades, the larger the bump. Very, very short segments, you might not notice the bump outside of the cab view. This becomes even more of a problem if it happens to be multi-track shapes.

In some future environment things may remain exactly as described, except perhaps that long curved segments are not available -- so there is still a bump of some magnitude. Or, if things get sophisticated and the track you've laid actually has a cant built into it, with run in and run out sections, then it would be exactly as a rail engineer would have built... all very smooth. But having track with a built in cant might (would?) be problematic for both Open Rails and MSTS.

Yes, obviously it doesn't fix things 100%, but with short enough segments things can be unnoticeable to the eye. It comes down to the usual trade off of segment size versus GPU power.

I just discovered a difference in the way MSTS and Open Rails handle dynamic track. The route I used is called Arollercoaster. Obviously, it's totally unprototypical, but being made nearly 100% of dynamic track it starkly illustrates the difference between OR and MSTS.

The first picture shows the route in MSTS. Note that the dynamic track indeed twists when you have a curve on a gradient. The train's wheels stay more or less on the rails. Both the rails and the train remain parallel to horizontal in the width-wise direction.

The second picture shows the route in Goku's route editor but OR handles it the same. Here apparently the entire segment of dynamic track is treated as one section, while MSTS apparently breaks it up into smaller sections. Note how the top of the curve section is not level. The train behaves the same as in MSTS as far as remaining parallel to horizontal, but because the track is not drawn correctly, the wheels are above and below the track on curved sections which are on a gradient.

The bottom line then is that Open Rails needs to draw dynamic track in much smaller segments to maintain MSTS compatibility. It doesn't currently do that.

Attached File(s)

•  Arollercoaster(MSTS).jpg (110.76K)
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•  Arollercoaster(OR).jpg (204.04K)
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[Genma Saotome]

What a wonderful example Joe, thanks for posting that. A picture really is worth a thousand words.

[SP 0-6-0]

The grade issue with bumps is annoying. However, In the real world steel can bend enough to take on the curved shape and thus becomes over time bent in some angle and in some fashion according the ROW on to which the rails are laid. The problem is simulating this property of metal in a 3d world is not so easy to make happen. If it does happen it will come at the cost of performance in computing power.

Robert

[WaltN]

jtr1962, on 09 September 2018 - 03:00 PM, said:

Yes, obviously it doesn't fix things 100%, but with short enough segments things can be unnoticeable to the eye. It comes down to the usual trade off of segment size versus GPU power.

I just discovered a difference in the way MSTS and Open Rails handle dynamic track. The route I used is called Arollercoaster. Obviously, it's totally unprototypical, but being made nearly 100% of dynamic track it starkly illustrates the difference between OR and MSTS.

The first picture shows the route in MSTS. Note that the dynamic track indeed twists when you have a curve on a gradient. The train's wheels stay more or less on the rails. Both the rails and the train remain parallel to horizontal in the width-wise direction.

The second picture shows the route in Goku's route editor but OR handles it the same. Here apparently the entire segment of dynamic track is treated as one section, while MSTS apparently breaks it up into smaller sections. Note how the top of the curve section is not level. The train behaves the same as in MSTS as far as remaining parallel to horizontal, but because the track is not drawn correctly, the wheels are above and below the track on curved sections which are on a gradient.

The bottom line then is that Open Rails needs to draw dynamic track in much smaller segments to maintain MSTS compatibility. It doesn't currently do that.

Assuming that your first picture is a screenshot from MSTS as you asserted, what is that double-line moving across the sky? Looks like it might be a "TDB-connector" from RE.

Also referencing your first picture, perspective can be very misleading. The ties seem to sloping in a clockwise direction in the foreground, which suggests a twist to the right. However, the left-hand side of ties is closer to the viewpoint than the right and lower than straight ahead from the viewpoint. Moreover, the twist crossover is about equal in altitude to the viewpoint, and beyond that point, we are merely looking at the underside of the track. Now, it surprises me that the underside is not culled out by the graphics routines. I don't recall whether MSTS displays undersides. I can't check it, because my MSTS doesn't work at all with the current release of Windows 10. Can someone with any experience report that? If that's the top side, then a 180-degree twist has to occur in the region where the perspective projection is most narrow. No way!

I have a definitive diagnostic test for you to perform. In the MSTS route editor if at all possible, construct a section of dynamic track of length 1.57 (full quadrant) and radius 100 m. Pitch it up at a grade angle of 3 degrees (MSTS max). Record the y-coordinate of the start of the section. Construct another track section (dynamic or non-dynamic). Retain that section at level (no grade). Record the y-coordinate of the start of that section. The difference between those two y-coordinates will give us the numerical change in elevation (delta-y).

Finally, take a close-in screenshot (IN MSTS!) at which the two sections join. Get close enough to the junction to judge whether there is any mismatch in alignment.

[WaltN]

SP 0-6-0, on 09 September 2018 - 08:37 PM, said:

The grade issue with bumps is annoying. However, In the real world steel can bend enough to take on the curved shape and thus becomes over time bent in some angle and in some fashion according the ROW on to which the rails are laid. The problem is simulating this property of metal in a 3d world is not so easy to make happen. If it does happen it will come at the cost of performance in computing power.

Robert

In the real world, bending steel to correct out-of-tolerance alignments causes increased wear on wheels' flanges. "Bumps" merely bother passengers and freight.