Templot Club Archive 2007-2020                             

topic: 3085dummy vehicle outline envelope - now in 215c
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posted: 26 Sep 2017 01:12

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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At present it's possible to leave copies of the dummy vehicle scattered about for clearance testing purposes.

But the exact spot where they need to be left isn't always obvious, leading to a lot of swapping to and fro between the dummy vehicle and making fresh copies of it.

So I thought it would be useful to generate a clearance envelope all along the length of a template, as if the dummy vehicle had been rolled from end to end.

I have added an extra button to the dialog for the purpose:

2_251946_090000001.png2_251946_090000001.png

The purple lines show the result. At this zoom level it looks a bit of a mess, but all becomes clear when zoomed in.

I'm creating a curviform double-junction there. It's usual to stagger the turnouts to ensure a running clearance (and also to make it easier for the rodding runs). But by how much? At first sight it would seem that the closest clearance conflict would be at A, but on zooming in it is found to be at B:

2_251946_090000000.png2_251946_090000000.png

Not by much, and these are the arbitrary clearance lines, not the actual bodysides. But even so it might be prudent to increase the stagger by snaking the turnout a bit further west. Or alternatively to increase the track spacing a fraction.

This new function to generate the dummy vehicle outline envelope follows the settings for the dummy vehicle dimensions -- in other words the same effect as making a great many vehicle copies. It can run along the main road or turnout road (as here) in the same way as rolling the dummy vehicle.

Like the copies, this outline envelope stays put on the trackpad if the templates are moved, it is not part of the templates. It would need to be deleted and regenerated afresh in that event.

In the next program update. :)

regards,

Martin.

posted: 26 Sep 2017 09:11

from:

Tony W
 
North Notts. - United Kingdom

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Hi Martin.
A very useful enhancement to the dummy vehicle function that will help make life easier in determining minimum clearances.
Regards
Tony.

posted: 26 Sep 2017 13:55

from:

d827kelly
 
Coventry - United Kingdom

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As Tony says, a very welcome useful addiction.

posted: 26 Sep 2017 15:03

from:

John Palmer
 
 

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I agree that this would be an extremely useful addition to Templot's capabilities, but may I make a suggestion about presentation?  I imagine that the multiple purple lines denoting the outline envelope represent the paths taken by a range of chosen points on the dummy vehicle as it traverses the template.  I can't see any useful purpose that is served by display of all of those paths; instead what I would want to see is the envelope representing the furthest projection of any part of the dummy vehicle in the course of such traverse.  That seems likely to be a combination of parts of the various paths denoted by the purple lines, but one is only interested in the parts of such paths that extend further out than any of the other paths plotted.  Only when the path plotted by one point crosses and lies outside the path described by any other point does it form part of the clearance envelope and need to be displayed.

Not sure I've expresssed myself very clearly, and what I am proposing may be of excessive computational complexity in any case, but them's my thoughts.

posted: 26 Sep 2017 15:33

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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John Palmer wrote:
Not sure I've expresssed myself very clearly, and what I am proposing may be of excessive computational complexity in any case, but them's my thoughts.
Hi John,

Yes you have, and yes it does represent a lot of extra maths. The above was coded fairly quickly by simply rolling the dummy vehicle and plotting the course of the corners and mid-side positions.

I realised that a single maximum-extent option would be preferable, and I was thinking of doing that by flood-filling colour between the lines. Which has the disadvantage of obscuring the track detail.

But maths is fun, so I will have a look at generating the maximum extent as a single line. :)

Thanks for all the positive comments.

regards,

Martin.

posted: 26 Sep 2017 15:44

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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Martin Wynne wrote:
Which has the disadvantage of obscuring the track detail.
p.s. it doesn't if I flood-fill each side of the track separately.

Often writing stuff here helps to clarify my thoughts. :)

Martin.

posted: 26 Sep 2017 19:30

from:

alan@york
 
 

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Would it be possible to only have overlaps coloured in?
alan@york

posted: 27 Sep 2017 14:18

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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Thanks for the comments.

The method of creating the paths of several fixed points on the dummy vehicle proved to be flawed.

By rolling the dummy vehicle over it, I found that on sharp reverse curves there were places where short sections of vehicle overlapped the drawn line by a fraction. To work properly, it would need lines drawn from an infinite number of points along the side of the vehicle.

No doubt someone with a better geometrical head than mine could have predicted that. :)

So back to the drawing board, and I have now drawn the full vehicle outline at frequent steps along the track:

2_270842_500000001.png2_270842_500000001.png

Yellow shows the maximum extent anywhere of the area swept by vehicle body, the purple section shows the clearance allowance each side. Rolling the vehicle over it proves it to be correct, but it is not always the corners or mid-points of the body which create the extent, as I found earlier. On a reverse curve such as this S-transition, you get necks in the envelope which look as if they must be wrong, but on rolling the vehicle it proves to be correct.

To get a reasonably smooth envelope I found that it was necessary to use very short steps:   

2_270842_500000002.png2_270842_500000002.png

The above created by drawing the dummy vehicle at 3" steps (full-size prototype!), and still it is less smooth than I would have expected.

To keep memory use sensible I have limited the length of the envelope to a maximum of 5000 3" steps, i.e. 1250ft of track, or 5000mm at 4mm/ft scale. If the template is longer than that the remaining length won't have the envelope over it. It would be necessary to split it into shorter templates if required.

And up to 8 such templates can be created at the same time on different templates.

Still some work to do on this to get neat results in practice on a full track plan.

regards,

Martin.

posted: 27 Sep 2017 15:11

from:

Raymond
 
Bexhill-on-sea - United Kingdom

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Martin,
This is a vast improvement on the method I used to use creating numerous vehicles and the new 'make a slip' is great. Thanks again for all that hard work.

posted: 27 Sep 2017 19:17

from:

Phil O
 
Plymouth - United Kingdom

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Excellent work Martin.

Thanks

Phil.

posted: 30 Sep 2017 02:03

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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Thanks for the comments.

This new function is now available in the latest Templot update. Version 215c.

Your copy of Templot should update automatically if you restart it and follow the instructions. If you have any problems with that, follow the download links on the web site.

 tools > dummy vehicle • spacing-ring menu item.

There are no docs yet for this function, please ask here if anything is unclear. :)

regards,

Martin.

posted: 30 Sep 2017 23:59

from:

John Palmer
 
 

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Just installed version 215c without any hitches, and tested the outline envelope facility.  A straightforward to use and useful addition to Templot's capabilities.  Most satisfactory - thank you very much, Martin.

posted: 19 Oct 2017 21:03

from:

dave turner
 
United Kingdom

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Martin I have to say that I like John Palmer's idea.

To see just the overlap of infringement(s) would be useful particularly if this could be toggled on/off for all the visible templates.

The difficulty would be spotting areas where only a pixel or 2 would overlap at the observed zoom level. Therefore a counter/tolerance/exaggeration method would need to be devised to ensure that any significant issues are visible.

You intimated that you liked a fun maths challenge!

Of course this isn't anywhere near as much a challenge as continuing update the documentation :D

regards Dave



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