Railway scanning hardware

Please post any tips or advice you have in general relating to laser scanning either whilst onsite or office based.
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richard_m
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Re: Railway scanning hardware

Post by richard_m »

MalteHC wrote:The Z+F scans 200 lines/sec, and the riegl scanner scans 100 lines/sec, but it has two scanners, so it is 200 lines/sec, right?
Hi,

I am not sure it works that way. If you have a single scanner on the front or back of a vehicle then the "sweep" of the scanner is a line perpendicular to the direction of the vehicle. If you pass a, for instance junction box, then the laser will hit one side only so you have to assume the corner positions of the side scanned and then the rest of the box. With 2 scanners, such as the Reigl they are set at 45? degrees to the direction of the vehicle and 90? degrees to each other so neither scanner is scanning perpendicular to the direction of the vehicle. This means that passing the same junction box will scan 3 sides of it. This I assume is the advantage of having a two scanner system and not a higher scanning resolution.

Richard.
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Re: Railway scanning hardware

Post by MalteHC »

It is endeed true that it is a big factor that it scanns the subjects from two sides, but the lines isnt on top of eachother? they are 90? degree orthogonal on each otcher (that furthermore creates a nice even gridnet) and i therefore has a hard tome to not see how 100+100 becomes 200 lines/sec?
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Re: Railway scanning hardware

Post by MalteHC »

For information is my conclution that the best way to scan railway, is to use 360 degree scanners, because it also gives you the oppertunity to calculate the space between the railway and it surrorindings (like trees). i have tried a couple of ways to extract the railways. at first i tried to extract the raillines by Bentleys Descartes, which turned out to be in really bad quality. the best way i found, to extract raillines, is to use terrasolid.
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Re: Railway scanning hardware

Post by DanCutler »

MalteHC wrote:at first i tried to extract the raillines by Bentleys Descartes, which turned out to be in really bad quality. the best way i found, to extract raillines, is to use terrasolid.
Hi Malte, can you expand on that please?
What don't you like about Descartes?
How do you use Terrasolid in this situation?
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Re: Railway scanning hardware

Post by MalteHC »

In bentley decsartes it defines the railwar, by the intensity of the scanned point, thats in fact means that it will find the raillines but not the top of the raillines! in draws a line, which i some cases is at the foot of the railline and other cases is at the top.

Terrasolid has created a add to find the raillines. It works by you defining a crosssection of your railway and it will extract the middle and top, which in my case worked great.
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