View Full Version : How to fix survey data z offset error?
7th Nov 2008, 01:47 pm
Hello all, i have a problem. Did some readings with Leika 805, and now i found out that all my points (~2000) Z coordinates are 6meters "over the limit". So is there any plugin, application that can modify all my points Z coordinates by +/-6 meters. It will take a whole day to do it manually 1 by 1. Somebody told me that Leika Geo Systems can do something (raise station by x meters, and automatically all point will raise too).. thank you
7th Nov 2008, 02:01 pm
First... what format are the points? Autocad points, ascii...?
7th Nov 2008, 02:13 pm
What CAD software are you using? Your profile says AutoCAD 2006. If so, and these are just POINT entities, you can use the move command to move the points in the Z direction.
7th Nov 2008, 06:16 pm
Something to try, because I can't actually check, would be to edit your fixed point in the theodolite data to the correct Z value, then down-load the measured data again. I thought that Leica saved all the theodolite readings, and did the calculations at down-load.
Or alternatively, download the data and send it to Excel, and adjust everything there.
Or alternatively, if all the spot levels are merely text on the drawing, adjust all the levels with a Lisp such as TextMath.
7th Nov 2008, 07:10 pm
Just had a play with my 705, and you can't do it in the instrument :cry:
So you will have to modify the downloaded data. Depending what format it is in, that could be easy or tricky :shock:
See if you can post a bit of data to have a play with :)
7th Nov 2008, 07:48 pm
well im still a noob, and my main language is Romanian, so i struggle translate them specific terms :D here's the sample, take a look at it, and tell me if all points can be lowered by 6.80m .
can't post links, so PM me to send you file to look at. need 9 posts
im new at work (age 20), and started 2nd "age" of college (topography), and will get the AutoCAD diploma soon (exam is on monday :D ). So any tips tricks would be great :D (the AutoCAD teacher only showed us 2D works, and teached us to draw lines, shapes, design screws, etc but it's almost useless since i work and study topography). AutoCAD is not an issue, soon will be getting the 2009 3D map version (need license first).
7th Nov 2008, 07:55 pm
i see there is no PM option on this forum.. so have to add some posts to post link.. need a couple more. Sorry for the double post, but i don't know why is it limited to 9 post before u can link something.. kinda silly, but 9 is not that much.
7th Nov 2008, 08:01 pm
Yes, there is that threshold to surmount first before PM privileges kick in. Don't worry as it looks you'll blow by that in a flash.
Private messages between members is a great way to take a conversation offline but it also deprives the rest of us a chance to learn something new. If your reply is in answer to the actual question consider keeping it here until such time as it strays off course. Just a suggestion. Feel free to handle it in any manner you are most comfortable with.
7th Nov 2008, 08:22 pm
If the data download is in Ascii text, then you could copy a few lines into the post :)
7th Nov 2008, 09:33 pm
It's not nice from me to do this, but you can forgive me for this one. Don't want to spam the other topics for 1 more post, so here's the link. put it together and download the file. look at it, and tell me what do you think, and what can i do:
(nvm.. i tricked the system.. had 8 posts, posted text without the link, then had 9, so i edited and pasted link :D Ain't I a smart fella' ? :D :D )
7th Nov 2008, 10:04 pm
I see that the drawing has alignments and cross sections already drawn. As these are to the wrong level datum, I think it would be easier to input the data again, but with the levels corrected.
Can you post a few lines of the surveyed data, before it gets into AutoCAD? Just ten lines will do to see what sort of data it is.
To correct everything in the drawing will be quite a task. The 3D lines can just be moved vertically, but some of the lines are joining the 3D level point with a zero point, so if everything is just moved vertically, then it won't be as it should be. With the sections, they would have to be altered one by one, again a long job. As I said, it would be easier to change the input data.
The attached screen shot is a front view of your data
7th Nov 2008, 10:17 pm
i can't send you a piece of data, since it's at work, and i think it's already deleted. After realising it's 6,80m above the required height (not my mistake, but an "experienced" guy blew it ), we split it up into x sections (my part is the one with Norby), and we change the numbers name (ie 87,00 to -6.80 so 80,20) to correct ones, then double click on the point next to the number, and set the Z to the same nr. Thats it.. oh.. and do the horizontal profiles (you can see them on the right).
P.S. are you suing CAD for topo, or for other thing? this is different than designing parts.
7th Nov 2008, 10:27 pm
The first lesson to be learnt with surveying is always save the field data. It may be wrong, but it can be altered. Much better than going out to take 2000 points again. :(
With the lines and circles that are in 3D, freeze all other layers, then move them by 0,0,-6.8.
With the numbers, again freeze all other layers, and use the Lisp TextMath. That will alter all the levels very quickly :D
You can use these techniques with the profiles.
I use AutoCAD for topographic surveys all the time
8th Nov 2008, 09:17 am
well i think we have the raw data on the leika, but not on PC. but if you move the whole drawing, the coordinates will be messed up (maybe disappear; X,Y but most of all Z). can you "show" me how.. ex take my dwg and try to do a part of it with your method, so that i can see. Still need alot of learning to "master" this program
8th Nov 2008, 09:53 am
As you have found out, moving the whole drawing does not give you what you want. One problem is that there are lines which have an elevation (z value) at one end and the other end at zero elevation. So if you move everything -6.8m in the z direction, then all the points which were at zero are now at -6.8. Not a good thing.
However, if you make a front view, you are now seeing everything as a section, with the y axis being the elevation. So now you can stretch everything that is at an elevation downwards by 6.8. You need to have ORTHO on, then use the command STRETCH, and make the crossing box so that the bottom line of the box does not include the zero elevation line. Then move everything by 6.8 downwards. If ortho is on, you just need to pull everything downwards and enter in 6.8 on the keyboard (direct entry distance).
Now make a top view, and all the lines in your plan will be at the correct z value. Now change the current layer to cote, freeze all other layers. Start the lisp TextMath, and subtract 6.8 (or add -6.8 ) to all text. This will give all (2587) the correct elevation text vales. Thaw all layers, and plan is now correct.
The Profiles are more complicated and will have to be done one by one. In the profiles there is a datum line which is a whole number (integer) of metres. The ground levels (Cota teren) will have to be altered but the Distante partiale and the Distante cumulate are to remain the same. The shape of the profile is to remain the same, but the distance from the datum line has to be altered. So by using stretch on each profile, you can alter them (all 86 of them) so that they are correct. If you are in a great hurry, you could just alter the datum value and all the ground levels, but it would not be conventional.
8th Nov 2008, 10:06 am
To move in the z direction without disturbing the x,y coordinates, the move distance to be typed in is @0,0,-6.8. That is a zero relative movement to the x and y axis, but -6.8 in the z axis. :D
8th Nov 2008, 10:49 am
hm.. need to experiment both of your posts. But the drawing is now messed up, because we all have our parts, and started to work on them. Will try both methods on original data (gonna get it from the leika). And the ones with the 0's ; i don't know what's with them.. have to ask my friend. he has some strange methods :D
8th Nov 2008, 10:59 am
I am very pleased that you are going to experiment. If you manage to get it all correct, then you will have learned an enormous amount. :thumbsup:
9th Nov 2008, 10:02 pm
gonna try it on thuesday (have exams before that). will be inactive while the exams.
11th Nov 2008, 08:32 am
wow, i tryed it and all worked as planned :? Thank you very much, you where right about the experience, i've learned alot. Hope you can teach me more of these "tricks" :D And thanks for the Textmath.. amazing and a must have. Do you create LISPs?
+++++ Reputation added :)
11th Nov 2008, 09:12 am
I am very pleased it has been successful for you. You have done the work :D
I am not very good at creating lisps, and usually follow what other people have created. When I started, this Forum was not here, so I have not had good tutors :shock:
11th Nov 2008, 09:22 am
the points with the 0 as Z are "bad points".. so we have to edit them and type in a random Z. thats not a big deal, since the one responsible for the error is going to do it :D
13th Nov 2008, 07:53 am
hm.. was thinking. Sometimes the Z of the point (the green circle) is lost in the leika, but the text remains (above the point). So is there any way to copy that number into the Z of the point? let's say a LISP with properties like select text, then select point, then it overwrites the Z (whitch is empty).. You know a faster method?
13th Nov 2008, 09:25 am
I am a bit puzzled as to the problem, and that data is getting lost in the Leica :?
I would have to know how you get the data from the Leica into AutoCAD.
Could you please post the x,y coordinates of an example of the problem, to save having to thoroughly search your drawing.
13th Nov 2008, 04:37 pm
well i don't have any data, but asked my friend and he said sometimes it happened, don't know how but did. Downloading using Geo office tools.
13th Nov 2008, 05:21 pm
Without an example of the dodgy data, it is very difficult to give a proper answer. I looked at your drawing, and could not see any green circles at zero. If the z value was lost, I would expect the green circles to default to zero. Also the text and point numbers do not seem to be at a set distance from the green circle :?
I personally download Leica data with a format that I wrote and insert all points into AutoCAD with a lisp that I wrote, so I keep full control of how the data gets into AutoCAD. Third party applications do it the way that they want, and sometimes it is not the most useful way :cry:
So in this case, I cannot say what has been going on. If you do find out some more, then come back to the forum and ask again.
17th Nov 2008, 09:49 am
text and point nr. are not the same dist. because it's hard to see it when there are 30 points in one location. The example to the 0 Z drawing would be correcting a riverbed.. we don't have enough points do we added some, and as we added some, the Z where 0. We had ~100 new points, so we manualy edited the Z's. Or is there a way to "reset" the Z to 0?
17th Nov 2008, 03:47 pm
When you are adding some 3D lines freehand (filling in points along a river bed), if you don't know the full 3D coordinate, but you know the z value of the point, try using .XY point filters. These allow you to pick the x,y point by picking on the screen then type in the z value. :)
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