Torsten, What about the inclination, is’t it this the problem of horizontal misplacement?
Check the „extend vertical“ command of centerline section in Thbook - it solves the problem with vertical shots they should be vertical after loop-closure. If you draw scrap with water area, there is the parameter of line "adjust horizontal/vertical“ for line point. It will align the line point with the previous one, so the water level should be horizontal. Martin S. > 3. 11. 2018 v 11:30, Torsten Schnitter via Therion <[email protected]>: > > Hi > > Concerning the loop closure problem I observed some more points. > > Following is the set: > A underwater cave with a GPS position at the start and at the water surface > (0m). > Inbetween there is a second surface point with also a GPS position at the > water surface (0m). > Then there is a second start of survey from inside the cave. We have a GPS > position of one point inside the cave (done with radio location). > Both surveys should come together at one point of course. > Due to underwater survey the x and y coordinates (compass) is not that > accurate and the two final points do not match exactly (of course not). > > In picture "Cave-Lake-without-loop-closed-plan-view" you can see the plan > view from this two points which are not at the same place (as expected). > In picture "Cave-Lake-without-loop-closed-elevation-view" you can see the > elevation view from this two points. > May be it's hard to see but both points are at the exact same level (which > they should be). > > (I draw a small scrap - red line - to show the water level (at correct level > 0m) before the loop closure.) > > After the loop closure I get some problems. > On the picture "Cave-Lake-with-loop-closed-plan-view" you can see the loop > closed and corrected in x and y orientation. > This seems to be ok (no problem with that). > On the picture "Cave-Lake-with-loop-closed-elevation-view" you can see the > elevation view after loop closure (it doesn't make any difference using > therion or survex as loop closure algorithm). > You can see the water level is not at the 0m level (scrap line) anymore, it's > far below that. The loop closure corrected the survey also in z orientation > although the two "end" points have been at the same level before and no > correction should have been necessary. > > Due to this corrections the "lake" inside the cave is not flat anymore but it > is bend somehow (high at beginning, lower in the middle and high up again at > the end). I assume everybody does agree it's not possible to have a lake with > bended surface. ;-) > > Due to this corrections I observed another point as well. > Having a vertical shot before the loop closures (and for sure this is > vertical!) this shot is not vertical anymore after the loop closures. > > In my opinion there are two points: > - Having corrections in x and y with loop closures doesn't mean implicitly > there is also a correlating correction to the z axis. Especially if the > points are at the same level already. > - With loop closure there should be a special treatment with vertical shots > (in x/y orientation) and with horizontal shots (in z orientation). May be > there should be no correction due to loop closures!? > > What do you think? > > Btw: > does anybody have a solution for my problem: No correction in z orientation > for this loop closure? > > regards, > Torsten > >> Torsten Schnitter via Therion <[email protected]> hat am 1. November 2018 um >> 21:23 geschrieben: >> >> Hi Martin >> >> I tried both loop closure methods. Survex and Therion. >> It doesn't make any difference. >> >> With both it's not at one level without the extra 0,01m for vertical shots. >> Both are correct with the extra for the shots. >> >> hth, >> Torsten >> >>> Martin Sluka via Therion <[email protected]> hat am 1. November 2018 um >>> 16:27 geschrieben: >>> >>> Thorsten >>> >>> have you try both loop closure methods - Therion’s and Survex’s? >>> >>> Martin S. >>> >>> >>>> 1. 11. 2018 v 16:09, Torsten Schnitter via Therion < [email protected] >>>> <mailto:[email protected]>>: >>>> >>>> Hi >>>> >>>> I figuered out the problem and may be there is a bug in loop closure... or >>>> somewhere else. >>>> >>>> The cave does start at 0m of depth and with a fixed point (fix 0 x y z) >>>> with z=118.4m. >>>> After roughly 800m of underwater cave survey (which does result in >>>> absolute z values for every station) the cave does surface again at a >>>> depth of 0m. >>>> I fixed this point as well (fix 0 x y z) with z=118.4m (to correct the x >>>> and y error). >>>> >>>> So far so good. >>>> But further (around 1km more) into the cave it does surface again and I >>>> realized in elevation view that 0m is not at the same level than the first >>>> two points are. >>>> As soon as I deleted one of the two fixed points the z elevation was as >>>> expected and the 0m point into the cave was at the same level than the >>>> first two surface points. >>>> >>>> After some tests I realized the start of the cave was the problem. >>>> You can see this part on the attached picture. >>>> As you can see there is a vertical start of the cave. >>>> >>>> Here the data from that first part: >>>> data diving station depth newline tape compass >>>> 0 0.0 >>>> 4.9 0 >>>> 1 4.9 >>>> 9.1 0 >>>> 2 14.0 >>>> 28.1 78 >>>> 3 28.2 >>>> 8.9 88 >>>> 4 30.3 >>>> >>>> As soon as I add 0.01m to the first and second (vertical) tape measurement >>>> (4.9 = 4.91 and 9.1 = 9.11) all is good and the problem with loopclosure >>>> is gone. Both fixed points are added again and the eleveation is as >>>> expected (0m level is at the same level at all points). >>>> So there is some more distance needed for the vertical parts. But I can't >>>> explain why. >>>> >>>> Is this a problem with the loop closure algorithm? >>>> May be some of the experts around can post a explanation for this >>>> behaviour!? >>>> >>>> regards, >>>> Torsten >>>> >>>>> Bruce Mutton via Therion < [email protected] <mailto:[email protected]>> >>>>> hat am 30. Oktober 2018 um 08:34 geschrieben: >>>>> >>>>> Torsten >>>>> >>>>> The image of the xvi file makes it look as though there is a loop (not >>>>> sure if it is a plan or elevation view – presume it is elevation). Also >>>>> if you have a fixed point at each end, then this could also cause ‘a >>>>> loop’ which might give differing elevations at each end. >>>>> >>>>> Also, if the water is flowing, then the water levels at each end will >>>>> actually differ. >>>>> >>>>> >>>>> But I assume you have correctly assessed these effects as negligible, or >>>>> at least not detected by your survey method. >>>>> >>>>> >>>>> I think you are implying that the 0m line is a raster background. If >>>>> that is the case, it may be distorted by Therion. One way to check would >>>>> be to turn on gridlines for the layout. That will show you what Therion >>>>> really thinks is a horizontal line. >>>>> >>>>> >>>>> Also check that Therion has the water surface survey stations at the same >>>>> altitude. You can check this easily by interrogating a .3d output with >>>>> Aven. >>>>> >>>>> >>>>> Bruce >>>>> >>>>> >>>>> From: Therion <[email protected] >>>>> <mailto:[email protected]>> On Behalf Of Torsten Schnitter via >>>>> Therion >>>>> Sent: Tuesday, 30 October 2018 04:36 >>>>> To: [email protected] <mailto:[email protected]> >>>>> Cc: Torsten Schnitter <[email protected] >>>>> <mailto:[email protected]>> >>>>> Subject: [Therion] ***UNCHECKED*** Problem with elevation view >>>>> >>>>> >>>>> Hi all >>>>> >>>>> I have a under water cave survey and all the data is done with depth >>>>> measurements. >>>>> So the Z coordinates are absolute and the survey is not with clino data. >>>>> The cave starts at one point and after roughly 800m you have another >>>>> surface point. >>>>> >>>>> When I compile the data I get a strange behaviour. >>>>> Although it's not a WYSIWIG map editor I would expect points which have >>>>> the same depth are at the same "depth"/level on the xvi file. But they >>>>> are not (see attached screenshot "elevation problem"). >>>>> The 2 points within the red marks do have the same depth measurements. >>>>> But if you have a closer look to it you can see they are not at the same >>>>> level. >>>>> (They differ somehow in x/y way and therefore the points are not on top >>>>> of each other.) >>>>> There are no loop closures inbetween which could be a reason for >>>>> different levels. >>>>> >>>>> Not having the same level with these points (I assume it is this point) >>>>> leads to a bigger problem later on. >>>>> When drawing the elevation scraps and putting a water surface (depth = >>>>> 0m) to the scraps and having a raster in the background, the surface at >>>>> the beginning of the cave is not at the same level than at the next >>>>> surface point of the cave. But it should be. >>>>> See pictures "elevation problem-start" and "elevation problem-end". >>>>> >>>>> What's wrong? >>>>> Can anybody help? >>>>> If more info is needed please let me know. >>>>> >>>>> Thanks, >>>>> Torsten >>>>> >>>> >>>> >>>> >>>>> _______________________________________________ >>>>> Therion mailing list >>>>> [email protected] <mailto:[email protected]> >>>>> https://mailman.speleo.sk/listinfo/therion >>>>> <https://mailman.speleo.sk/listinfo/therion> >>>> >>>> >>>> >>>> <Entrance-1.JPG>_______________________________________________ >>>> Therion mailing list >>>> [email protected] <mailto:[email protected]> >>>> https://mailman.speleo.sk/listinfo/therion >>> >> >> >> >>> _______________________________________________ >>> Therion mailing list >>> [email protected] >>> https://mailman.speleo.sk/listinfo/therion >> >> >> > > > >> _______________________________________________ >> Therion mailing list >> [email protected] >> https://mailman.speleo.sk/listinfo/therion > > > > <Cave-Lake-without-loop-closed-plan-view.JPG><Cave-Lake-without-loop-closed-elevation-view.JPG><Cave-Lake-with-loop-closed-plan-view.JPG><Cave-Lake-with-loop-closed-elevation-view.JPG>_______________________________________________ > Therion mailing list > [email protected] > https://mailman.speleo.sk/listinfo/therion
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