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posted: 6 Feb 2009 18:00 from: GeoffB click the date to link to this post click member name to view archived images |
Hi All, I need to build some new crossovers in a couple of places on my O gauge garden railway. The existing track is not straight in the places that I need to fit the crossovers. How would I go about getting a background or whatever to work to. I had thought of setting the camera up on a tripod and photographing (vertically on a longish lens to alleviate divergence - I can get the camera up 3-4ft over the tracks easily enough) a series of shots along the track where I want the crossover, then stitching them together in Photoshop and using as a background to build the templates to. Is there a better/easier way than this? I suppose that some of you must have done this before. Regards, GeoffB |
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posted: 6 Feb 2009 21:43 from: Martin Lloyd
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May seem a daft idea but what about doing a sort of 'brass rubbing' with a roll of paper, fastened so that it won't move, then rubbing with a wax crayon. Then scan it. | ||
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posted: 7 Feb 2009 00:32 from: Nigel Brown click the date to link to this post click member name to view archived images |
I'd suggest doing a quick "survey" of the existing track. You're obviously going have to rip some up. Work out at what points you want the ends of the ripped out bit to be. Take one of the two points and lay a straight edge at a tangent to the rail. This gives you the direction of that rail and can also act as the X axis. Take another straight edge and place it perpendicular to the first edge so that it passes through the second point. That enables you to measure the relative X,Y co-ordinates of the second point. Now move the second straight edge so that it is tangential to the rail at the second point and so that it crosses the first straight edge. You can now measure the angle between the tangents. This gives you enough information to go into Templot and draw a couple of pieces of track representing the ends of the track you're going to leave in place; they can be straight, they don't have to be the same shape as the ones in the garden. You can also double the tracks using the spacing you used in the garden. You now have the gap you want to fill; just carry on and use Templot to fill it with a crossover, forgetting about the actual shape of what was in that position in the garden. |
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posted: 9 Feb 2009 12:49 from: GeoffB click the date to link to this post click member name to view archived images |
Martin Lloyd wrote: May seem a daft idea but what about doing a sort of 'brass rubbing' with a roll of paper, fastened so that it won't move, then rubbing with a wax crayon. Then scan it. Hi Martin, I did think about this route as well as photographing - might be an idea to look at this. I just wondered how others go about it and if there was an easy way. Regards, GeoffB |
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posted: 9 Feb 2009 12:59 from: GeoffB click the date to link to this post click member name to view archived images |
Hi Nigel, Thanks for the reply. Took a little thinking about but I think I follow you on that one. I can see that that would work quite easily with parallel tracks or constant curves, but one of the problems in a couple of areas is that the tracks are not parallel an are on a slight divergence and a transition, so that would mean taking the extra measurements to get the divergence and transition and I'm not sure that it would come out right. I will have a look at that for the straight forward ones - it may be a quicker way than photographing or scanning, etc. Regards, GeoffB Nigel Brown wrote: I'd suggest doing a quick "survey" of the existing track. You're obviously going have to rip some up. Work out at what points you want the ends of the ripped out bit to be. Take one of the two points and lay a straight edge at a tangent to the rail. This gives you the direction of that rail and can also act as the X axis. Take another straight edge and place it perpendicular to the first edge so that it passes through the second point. That enables you to measure the relative X,Y co-ordinates of the second point. Now move the second straight edge so that it is tangential to the rail at the second point and so that it crosses the first straight edge. You can now measure the angle between the tangents. |
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posted: 9 Feb 2009 13:16 from: Nigel Brown click the date to link to this post click member name to view archived images |
Hi Geoff Yes, for simplicity I was assuming you could derive the second track from the first. However, it's only a bit more work (and possibly for accuracy a good idea anyway), to measure the position and angle of each end point of the second track relatives to the corresponding end point of the first track. cheers Nigel |
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posted: 10 Feb 2009 11:47 from: Andy B click the date to link to this post click member name to view archived images |
You could try just 1 or 2 photos that capture the whole formation, then use GIMP (search the forum for Martin's examples of its use) to manipulate the pictures. Should be easy to set the transformation needed, as you can take a few exact measurements to check it. Andy |
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posted: 10 Feb 2009 20:08 from: GeoffB click the date to link to this post click member name to view archived images |
Andy B wrote: You could try just 1 or 2 photos that capture the whole formation, then use GIMP (search the forum for Martin's examples of its use) to manipulate the pictures. Hi Andy, I will have a look at both ways of doing it (photos and measurements as suggested by Nigel) to see what transpires for future reference. I can set up the camera at about 4-5ft over the track and I will be using Photoshop to stitch together and manipulate as ness - use it daily in my professional life. Thanks, GeoffB |
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