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Post by Prudent_Regret on Nov 8, 2021 1:07:58 GMT
The most relevant unknown is the focal length of the lens (i.e. zoom). The focal length can indeed have significant impacts on the perspective of an image. For example, this image shows two images taken at the same angle but with different focal lengths:  You can see how the sizes of different objects appears very different based on the focal length. Again, these are taken at the same angle, even though it seems the bridge is much larger. However, that does not impact our analysis. The relative width of the rails is what we are interested in, and the focal length does not change the width of the rails from each-other relative to the rest of the images. Here are the two images overlapped with the vanishing point corresponded, and the analysis shows they are indeed the exact same gauge:  So this analysis requires no assumption of the focal length of the cameras. It works regardless of that difference. What Oozy is doing is taking photographs from completely different angles (like from standing on top of a train platform) to try to find correspondence. But the image I have provided, which is actually a similar angle as the Treblinka spur, shows that this was a metre-gauge railway. |
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blake121666
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Post by blake121666 on Nov 10, 2021 8:53:50 GMT
From the logic you are propounding, if I were to take a picture of 2 sets of parallel rails - one set inside the other and therefore that inside set is of a narrower gauge - they would create the same exact angle at vanishing point on the horizon of the picture. The sole difference between these 2 sets of rails would be the width between their rails at any point.
But we never know absolute widths in that picture and the way you are determining the vanishing points is kludgy at best. So if I were to take the picture and a copy of it, and in the first I delete the set of inside rails out of it and in the second I delete the outside rails out of that, then I could line these 2 pictures up showing that those rails are identical by sliding the wider gauge rails upward until the widths are the same in the 2. The angle is the same after all. Any width is simply the the width at a point along the legs of the angle (the rails are the legs of the angle here) going outward.
The only difference would be the vanishing point. But you don't even HAVE any vanishing point in any of these pictures.
The point is that the angle is the same for both sets of rails - and the inside set is narrower than the outside set (it actually being contained within the outer set).
So your angle comparisons are CLEARLY BOGUS comparisons.
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Post by Charles Traynor on Nov 10, 2021 22:13:30 GMT
From the logic you are propounding, if I were to take a picture of 2 sets of parallel rails - one set inside the other and therefore that inside set is of a narrower gauge - they would create the same exact angle at vanishing point on the horizon of the picture. The sole difference between these 2 sets of rails would be the width between their rails at any point. But we never know absolute widths in that picture and the way you are determining the vanishing points is kludgy at best. So if I were to take the picture and a copy of it, and in the first I delete the set of inside rails out of it and in the second I delete the outside rails out of that, then I could line these 2 pictures up showing that those rails are identical by sliding the wider gauge rails upward until the widths are the same in the 2. The angle is the same after all. Any width is simply the the width at a point along the legs of the angle going outward. The only difference would be the vanishing point. But you don't even HAVE any vanishing point in any of these pictures. The point is that the angle is the same for both sets of rails - and the inside set is narrower than the outside set (it actually being contained within the outer set). So your angle comparisons are CLEARLY BOGUS comparisons.
Good call on this one, LilGreyRabbitOfInle. If PR wants to prove his point he needs to head to Poland and take some legit photographs of the width of the tracks in question with a tape measure in clear sight.
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blake121666
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Post by blake121666 on Nov 10, 2021 23:30:18 GMT
He needs to establish a common metric between any 2 pictures. Then he can compare lengths between pictures. He instead thought he could use the camera angle to somehow determine a common metric - along with his faulty ray-tracing to a horizon (which isn't even there in his pictures). He obviously cannot do that.
And he is also implying that this museum quote from the 2nd post is either mistaken or a lie:
Why would the museum be mistaken or lie about the the main spur being of wide gauge as opposed to T1's narrow gauge rail-line in the quarry itself?
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Post by Prudent_Regret on Nov 11, 2021 2:01:45 GMT
From the logic you are propounding, if I were to take a picture of 2 sets of parallel rails - one set inside the other and therefore that inside set is of a narrower gauge - they would create the same exact angle at vanishing point on the horizon of the picture. The sole difference between these 2 sets of rails would be the width between their rails at any point. I don't get your point. Yes, all parallel lines converge to the same vanishing point. But they don't have the same angle at the vanishing point, as that angle would be wider for the wider rails. Here is an example:  The "European Standard (1435mm)" in red clearly forms a wider angle at the vanishing point than the inner, narrow-gauge identified in blue. There is no way you could crop or rescale the narrow-gauge rail to make it match the European standard gauge. Parallel lines do not work that way. But we never know absolute widths in that picture and the way you are determining the vanishing points is kludgy at best. So if I were to take the picture and a copy of it, and in the first I delete the set of inside rails out of it and in the second I delete the outside rails out of that, then I could line these 2 pictures up showing that those rails are identical by sliding the wider gauge rails upward until the widths are the same in the 2. The angle is the same after all. Any width is simply the the width at a point along the legs of the angle (the rails are the legs of the angle here) going outward. The only difference would be the vanishing point. But you don't even HAVE any vanishing point in any of these pictures.The point is that the angle is the same for both sets of rails - and the inside set is narrower than the outside set (it actually being contained within the outer set). So your angle comparisons are CLEARLY BOGUS comparisons. I think you're pretty confused as none of what you are saying is making any sense. How is the way I am determining the vanishing points "kudgy?" Do you know what a vanishing point is? Here's the wikipedia article on vanishing points. You can even see an image the article uses as the canonical example for "vanishing point": "A vanishing point can be seen at the far end of this railroad." It's not complicated to find the vanishing point of parallel lines, and they are in the photographs. We do know the absolute widths by using references image containing railways of a known gauge. 1435mm is a standard gauge rail. So using a photograph of a known standard-gauge railway, like the one running through Birkenau, is a valid point of comparison. I do not have to go to Poland to know that "standard gauge" is 1435mm width. For example, here is a picture of the track at Birkenau, which is a standard gauge:  Here is a another picture of a known standard-gauge railway from the same angle, this one is in Tanzania:  I don't need to go to Poland or Tanzania to measure these, unless you for some reason doubt the sources that say they are standard gauges. And they do have the exact same angle at the vanishing point, showing they are the same gauge as expected.  In fact, this image at Birkenau was also taken in a nearly-identical angle-of-view of the Treblinka spur in August 1944. Here they are side-by-side:  It's pretty clear from this that the Birkenau railway is wider than the Treblinka spur. But we can still align the vanishing points and show that the Treblinka spur has a narrower angle, showing that it is a narrower gauge:  In short, your criticisms don't make any sense. This analysis is valid and it shows that the Treblinka spur was a narrow-gauge railway. |
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Post by Charles Traynor on Nov 11, 2021 20:17:05 GMT
Here is a another picture of a known standard-gauge railway from the same angle, this one is in Tanzania: I don't need to go to Poland or Tanzania to measure these, unless you for some reason doubt the sources that say they are standard gauges. And they do have the exact same angle at the vanishing point, showing they are the same gauge as expected. I don't doubt the sources of standard rail gauges. However, I do doubt the source who claims the line below is narrow gauge. Visually it does not look very narrow gauge to me. It makes no business sense to invest in building a narrow gauge railway which is only centimetres smaller than standard gauge.
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Post by Prudent_Regret on Nov 11, 2021 22:47:41 GMT
I don't doubt the sources of standard rail gauges. However, I do doubt the source who claims the line below is narrow gauge. Visually it does not look very narrow gauge to me. It makes no business sense to invest in building a narrow gauge railway which is only centimetres smaller than standard gauge.
The left is a picture of the Malkinia-Siedlce line at the exact location that photo was taken. You see the Malkinia-Siedlce line on the left side of the picture? This is what it looks like when you are standing in front of it:  Does the railway on the left look like the same gauge as the one to the right in your view? Obviously not. The Treblinka Spur looks the exact same as this metre-gauge railway and it corresponds in angle when you align the vanishing points:   |
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blake121666
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Post by blake121666 on Nov 12, 2021 2:52:26 GMT
 This is what I meant. I screwed up the description about the angle. I meant the perspective angle is the same for the 2 sets of rails. The inner rails were cropped out of the bottom of the picture and made to coincide with where the outer rails have the same width. The vanishing point moved up, of course. But you are not determining the same vanishing point with what you are doing. You are comparing two different pictures and pretending that each picture has the same vanishing point when you line them up. You can't do that. There are any number of things which would warp the view taken in a different picture. You need something other than this - something of objectively known lengths in each picture - to be able to nail down a metric you can compare with. |
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Post by Prudent_Regret on Nov 12, 2021 3:18:55 GMT
This is what I meant. I screwed up the description about the angle. I meant the perspective angle is the same for the 2 sets of rails. The inner rails were cropped out of the bottom of the picture and made to coincide with where the outer rails have the same width. The vanishing point moved up, of course. But you are not determining the same vanishing point with what you are doing. You are comparing two different pictures and pretending that each picture has the same vanishing point when you line them up. You can't do that. There are any number of things which would warp the view taken in a different picture. You need something other than this - something of objectively known lengths in each picture - to be able to nail down a metric you can compare with. What do you mean "the vanishing point moved up of course." You are proving my point. Feel free to crop and rescale the section however you want. If you align the vanishing points then the angles will be the exact same. Cropping and re-scaling the image will not impact the angle of the lines at the vanishing point. You have cropped the image but not aligned the vanishing point, so I don't know what you think you are doing here. If you actually aligned the vanishing point with the middle-cropped out section, you would be proving my analysis. Instead you post an image where the cropped section is not aligned with the base photo and you think you are making some sort of argument? What do you mean "I am not determining the same vanishing points?" Can you please tell me how I have misplaced the vanishing point in this photograph? Where do you think the vanishing point is that is so different from what I have drawn here?  "You need something other than this - something of objectively known lengths in each picture - to be able to nail down a metric you can compare with." This is false. The photograph contains sufficient information to draw the conclusion that this is not a standard-gauge railway. Nothing you have said has contested my analysis that shows this. |
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blake121666
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Post by blake121666 on Nov 12, 2021 3:30:52 GMT
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