Adjusting Points, especially elevations

[nara7ZXKX]

Hello All, 

I previously posted asking for help with what embarrassingly turned out to be a very simple first step.  Now I’m trying to get a little more complicated and legitimately struggling with all my points. 

I only have AutoCAD, not Civil3D. Although I seem to be confusing myself because years ago it was Civil3D I worked with, and I recall some of those capabilities...  

The Map3D toolset is available as part of my company’s subscription, but I don’t know whether it would help me any. Perhaps? 

Ultimately, I’m wanting to create site plans that landscape designers can then work from. 

The Moasure device I mentioned previously is really cool and doesn’t need line of sight like survey equipment, but there are rotational accuracy limitations that increase with distance from the origin and I’m needing to adjust those and tidy up in AutoCAD. 

My boss had a Disto S910 gathering dust and so I want to use it like a mini total station and gather control/check points.  It can only store 30 points per file.  

Here is a screenshot from the dwg wherein I’m comparing 2 files of 28 points from the Disto (blue linework; magenta Points with Orange or Red descriptors respective to file 1 or 2) against  the linework (cyan, lime, orange) from 3 Moasure captures and some white points imported separately from the Moasure's csv file converted into a script from yet a 4th test capture familiarizing myself with the device and testing its repeatability (and my skill with it, so that’s why some pathwork is so rough!).  

Both the Moasure and the Disto S910 save the first point captured as 0,0,0. The Moasure then takes the next shot positively on the X Axis, but the Disto goes negative. So, the first thing I need to do to compare their information is to rotate the Disto’s output 180 around the origin. 

In all but one of the Moasure runs,  and both Disto tests, I started collection on the corner or the patio where I’ve sketched a white arrow. The polygons on the south east side of the image are raised vegetable beds. Where they appear straighter to the y axis but the house is skewed, in cyan, the origin was in the north east corner of the patio but I moved the associated linework to stack the south west corner and compare like for like. 

If I’m making sense, hopefully you can understand why I would want to get some control points at the southeast corner of the house with the Disto to tie the Moasure data back into correct rotation. And I want to start a new baseline with the disto to collect information at that side of the house that’s spatially closer together and therefore more accurate. 

So, that would be at least 2 new series of data, also both starting at 0,0,0 that I want to transfer to different coordinates in all 3 dimensions. And I’m not sure how to go about doing that now. 

For one thing, I don’t understand why the white points from my csv script came in on zero elevation.

Here's a snip from the script: 

I’ve “appload”ed Point Manager | Lee Mac Programming (lee-mac.com) that I learned about on these forums, but the help button doesn’t work for me and I'm stuck going any further for now. 

Thanks in advance for any suggestions you may have! 

[autoid374ceb4990]

As a retired civil engineer and land surveyor I would first ask if you have tested your measurement devices against some known measurements to see if they are both accurate?  Are your measurements from both instruments taken from the same point?  How are the coordinate systems set on each instrument?  I would guess that 0,0,0 is the instrument location but how is the X or Y axis set?

[nara7ZXKX]

Thank you @autoid374ceb4990  for the reply. As it so happens, years ago I borrowed a total station from a friend and topo'd my property before having some changes made. However the driveway and concrete patio have remained the same so that's why I've been using them for my tests. 

For the survey, my first traverse hub was at the base of the driveway and I called its position 5000,5000,100. I just copied it all in as a block into my comparison drawing, but I could adjust all my points in excel so that the corner of the patio is 0,0,0 like the Moasure and Disto S910 files are. 

Here you can see the cyan line, where I was getting more familiar and comfortable with the Moasure aligns relatively well with the driveway whereas the darker green (first go) was good on the west but became wide on the east. And the orange (2nd try) was rotated.

 

Like I say, I could adjust the point file of the survey and reimport it. Because here you can see the elevations are different, but they seem consistent.  

I need to figure out how to adjust the points within the CAD though. Because as this example is progressing, the elevations at the bottom of the property would be negative, wherein they are actually at about 60m. 

And like I say, the Moasure gets less accurate the further you go from the origin in each file, so I’ll be wanting to mesh multiple areas together using different files that will each default to starting at 0,0,0. And that’s why I want to use the Disto S910 as a control to tie known points together between the files. 

I used to be a survey tech but had to stop due to health problems. I'm trying to find a niche for myself wherein I can measure residential properties for garden redesigns. So these plans will be more conceptual and certainly don’t need mm precision.  

I can figure this out if it’s just 2D linework, but it’s the elevations that have most landscapers scratching their heads, so it’s those type of jobs I’m more likely to get.  

[autoid374ceb4990]

I will ask again - How are the coordinate systems set on each instrument?

If you move all the points from the Disto file up/down to match a known point of elevation, would the elevations in the Disto file then be correct?  You can do this within AutoCAD.  It appears that the X,Y coordinates are somewhat close to your total station points and just need to be moved/rotated to fit.  This can also be done easily in AutoCAD.

[nara7ZXKX]

Hi again, 

I guess I'm not sure I understand your question about the coordinate systems. I’m not interested in moving the data points to match GPS latitude and longitude or anything. They can stay arbitrary, I just don’t want to wind up with negative elevations anywhere within the final drawing.  

Both the Moasure and Disto can switch between various imperial or metric units and I’ve set them up to match. Both store a first point in any file as 0,0,0 and the second defines the x axis. Say there’s 10m horizontally between my first two points and no grade change and I record them in the same order. The DXF from the Disto shows the second point as –10,0,0 while the Moasure shows the second point as 10,0,0. I then need to rotate one of these exports about the origin so that the second points stack and all other data collected is spatially accurate regardless of whether it was Disto'd or Moasure'd.  

Patching just 2 files together is straight forward as it’s simply the rotation. But for example, I will want to “traverse” around the corner of a building. So, say with the Disto I store 2 points that are -20,+10,-10  and –20,+5,-10 initially relative to my original 0,0,0 but in the Moasure those same points are +20,-10,-10 and +20,-5,-10. In CAD I will have rotated the Disto data 180° to match  the Moasure’s info. But then I’ll bring in a new Moasure file that will have everything starting again at 0,0,0 and 0,5,0 I will want to move all that information tied +20,-10,-10 and +20,-5,-10 respectively. So it’s a translation, rotation, AND vertical adjustment. 

In the end I just want to have some 3D line work and spot elevations, possibly contours. I know the contours may not be possible as that was a Civil3D thing, but it’s been so long since I manipulated points in AutoCAD that I’m at a loss for how to proceed. 

Thank you for your help! 

[autoid374ceb4990]

OK so you are trying to run a traverse with an instrument that was not really designed to do so.  Just to simplify let's use just the Moasure instrument and you set it on point #1 (0,0,0) and measure 10 points with point #10 being at +20,-10,-10.  Then you move the instrument to #10 and shoot back to #1.  What coordinates do you get? -20,10,10?

Could you take a small example of two sets of data where you move the instrument, as in my example, and post the files here?

Assuming that you primarily want ground elevations, do these instruments us a target?  If so is the target mounted on a rod?  If the target is mounted on a rod how do you adjust the elevation to ground?  Normally with a total station surveying instrument you would know the instrument height and the rod height which could change with each shot in order to get an accurate ground elevation.

[richard_387]

I think that the Moasure is an inertial platform, that only measures relative displacement between points whilst the instrument is switched on. The quality of data depends on the handling of the instrument, attached as it is to a stick. As all the gyros have been miniaturised, it must be a very complicated and perhaps delicate bit of kit. Each session of gathering data is thus an entity in itself, and does not necessarily relate to any other set of data, hence the need to move data from different sessions around to get an overall mapping.

The Disto S910 has accurate distance measuring but rather less accurate angle measuring. Again, each data file must be considered as a separate entity.

So it is probably easier to plot each set of data on its own, and then move each data in its entirety, using matching common points to build up an overall picture. 

I would plot each set-up individually and make blocks. These can be moved in 3D and rotated to match. The blocks then being exploded when in final position.

[nara7ZXKX]

Effectively yes. This toy is a fraction of the price of a robotic total station. It’s an inertial square hockey puck that records where the corner stops. No target prism or rod height to worry about. There is a setting to change whether it’s being handheld or at the end of a stick. But there’s barely a cm difference in it. Here’s a Youtube tutorial about what I’m trying to do with it.  

I’m pushing it to its limits with the level of complexity I may want with some situations.  

For each new shape or entity that I want to record (ie driveway or vegetable beds) or “layer” in its terminology, I need to go back to the initial two points and it needs to stop every 6-8 seconds to at least record a “pause point” which I may want to filter out.  

So, to save a lot of walking and irrelevant point captures (especially when I have to get around obstacles like fences) I want to be able to have multiple baselines which act as traverse hubs that I store as different Moasure files and merge into one drawing later.  

So that’s why I want to bring in the Disto as a control check. That’s like a reflectorless resection. So, target height 0. But as you can see from the attached photos that come in with the DXF export, the laser can be very hard to see in the bright sunshine which I am likely to encounter often. Also, it’s time consuming to take a shot and there’s limited storage capability.  

Please see my "examples"  folder of 4 files I'd want to piece together. Please ignore the clutter in my “Compare” dwg. Each colour of linework is a different practice run with the Moasure where I’ve been experimenting with the technique of using it.  

I can manipulate these as blocks that I’ve patched together from each export, but it’s the 3D aspect that I’m struggling with.  

[nara7ZXKX]

Hi Richard, 

Yes! It's a very finicky little device. But pretty cool! The analogy of taming a horse comes to mind.. Learn to use it properly and eventually make pretty pictures / win the dressage routine. I’m so far finding I have better control and higher accuracy with it when moving it about by hand rather than within the stick. But that means more bending.

There are multiple export options with the Moasure and I’d like to be able to have as much linework as possible completed with it to save drafting time later. But then I will also want to have spot elevations. So that’s a need to edit the CSV file into a script to import.  

When opening a DWG directly from the Moasure export, the points are actually 4 lines as I complained about in my first post. After getting the space correct between the command for _MULTIPLE and _POINTS I managed to get them in and adjust the PTYPE to something workable and visually appealling. But I haven’t been able to get the elevation label to appear with that yet.  

So, I want to have an elevation label associated with the points I choose to keep as spot elevations when I finally get all my separate entities assembled in the best way possible relative to one another based on the redundancy checks I make with the disto and a handheld tape, notes, etc.  

[richard_387]

I see that the data in the two surveying systems is different. In the Disto 3D dxfs, there are AutoCAD Points. In the Moasure dwgs, the objects that look like Points are actually 4 lines.

Keep each run separate until you have matched them up and it will be easier to Move and Rotate the whole of one run at a time. Using the correct Object Snaps, it is simple to move one lot of data to a common point in 3D.

[nara7ZXKX]

Hi Richard,

Thank you so much for your help with this!

So here I've made each layer from the Moasure into a block and have combined in some disto observations as well.

As you can see, the csv from the Moasure directly is a bit strange as the point numbering resets on every new layer and "path" type. I just took the x,y,z and made a .scr which wouldn't load here so it's just the txt.

So, with this example, I can move the linework of each layer/block around individually. But the points are all currently simply that and independent of the linework. I want to edit the script to be able to show the elevation value. 

I suppose I ought to block the points also to their relevant layers and keep them separate. But that seems further cumbersome. Surely there's a lisp to speed this up, but I'm limited in my ability and understanding with regards to that. 

I would also like those first labels to be dynamic in that the elevation value displayed changes when the point moves vertically. Or, should I keep them as just the symbols while I adjust the orientation of everything, choose what to keep for spot elevations because I don't need clutter, and then export and reimport the points I've chosen to keep and then have only those with elevation labels? Surely there's a display option of whether the elevation value is visible or not?

[richard_387]

You seem to be constructing a whole new surveying method with exciting new technology. As I have used EDM surveying instruments since the Distomat Di10, my thoughts may be a bit dated.

I am concerned that you need to turn the Disto data through 180°. One of the system's data is not set up correctly. I presume you have checked with satellite mapping to see which way is North? It is a pity that Moasure cannot draw AutoCAD Points. The Point numbers in the Moasure csv file can easily be changed to give consecutive numbers.

I would have set up the blocks simply as block A. B etc - much easier to insert rather than 8 character named blocks. Keeping the sets of data makes it easier to move and rotate that entire set when zoomed in to one point.

As regards ground elevations, you could probably use fields which should update when moved. I use an old version of AutoCAD before fields were invented so I cannot check my thoughts. I would do as much editing of data as I could in a spreadsheet and then plot out the results with Lisps that I wrote 30 years ago.

I hope you manage to succeed with your combination of technologies to give a less expensive "near enough" survey. It only costs money to wander around with a GPS based system.

[autoid374ceb4990]

Richard:

If I understand one of the previous posts the reference direction has nothing to do with North, East, etc. but is based on the first reading with East (or West depending on which device is being used) being set as the reference direction for each group of shots taken from that base point.  So to complicate things, when the location of the base point is changed, the reference direction changes.  I was trying to get the OP to tell me what the reading would be if the instrument was moved to a new location that was one of the points taken in the previous setup and the first point taken would be the base point for the first data set, like running a traverse, but I guess he did not understand my question.

P.S. - My first EDM was an HP 3805, circa 1974.

[richard_387]

Looking at the manual of the Disto S910 there is mention of calibrating a compass, so I was wondering if the compass could be put to use. The Disto measures distances to +/- 1mm at up to 300 m, so triangulation comes to mind. But with the significant sight problems in the landscape environment, triangulation might not be feasible. With the Inertial platform to infill between control points, it could be the beginnings of a system!

P.S. I seem to remember the HP 3805 being a bit unwieldy on top of a theodolite. Had to operate it with a very light touch.

[autoid374ceb4990]

The 3805 had a Kern base and we used Kern tripods, measure the angle with a 1 sec. theodolite, remove theodolite, place 3805 on tripod to take distance.  A bit time consuming compared to the new stuff, but boy was it accurate.  Just retraced a 1975 survey  that we did on some really rugged woodlands with one of the new RTK GPS units and on a 2550' line there was only a 0.03' difference in the distance between old and new measurements.  But we are getting a little off topic.

[nara7ZXKX]

Hi Richard and Enthusiast. 

Please see attached both simply “Combined” and “Adjusted Tests”.  

I put some painters tape randomly on the floor and moved the Moasure around to the corresponding corner joints in the hardwood floor. 

For both Tests 1 and 2, I started at labelled "Point 1" and followed with "Point 2". This set the orientation. For Test 3 I started on “Point 4” and went to 5, for Test 4 it was Points 3-4, and for Test 5 I started on Point 8 and went to Point 7. So, in the “Combined file”, Points 4, 3, 8 and 1 are all on the Origin.  

Once they are adjusted to match, you can see that while not perfect, the discrepancies are acceptable for the use I intend with this device. The landscapers have told me 1’ tolerance is fine. But I want to use the Disto to tighten that up! 

All these 5 tests together around my kitchen/living/dining room took me less than 20 minutes. My struggle is namely that I’m finding the 3D linework difficult. I need to increase my efficiency on that front. I understand that blocking things together until I'm satisfied with their layout relative to one another is the way to go, but I know there’s got to be a way to make that somewhat automated, I just don’t know where to start with writing a lisp. And I’m still struggling to make an imported point have any annotation. 

For my own sanity, in a landscape environment, I am choosing to start the Moasure on an approximately West-East line squared to a home or other building so that everything plots with “North” at the top. Then I use municipal mapping services, or simply Google satellite view, to figure out how I should adjust the north arrow with respect to the building's roofline. 

I have the compass in the Disto set to saying I’m in Vancouver, but that doesn’t seem to make any difference. It just arbitrarily seems to go right to left rather than left to right. So, I think to spare that rotation, I will start each file with it on “Moasure Point 2” and then capturing “Moasure Point 1” before anything else. 

Going outside now to test that!

[autoid374ceb4990]

Remember to take the magnetic declination into account when figuring true north, about +15.73° for Vancouver😀.  

[richard_387]

The variation in the test surveys shows that the repeatability of the measurements is not yet perfected.

Because of this lack of fit, I would prefer to adjust the sets manually instead of going an automated route, because there is no correct solution. Perhaps diagonal measurements with the Disto could help.

Anyway, this is all going a bit further than AutoCAD.

[nara7ZXKX]

Yes, indeed it is not perfect! But that’s why I’m more confident bringing in the Disto to take common points from multiple locations to tighten up the error. 

But because this is meant to create less expensive plans for conceptionalizing, I can’t spend so much time adjusting everything that we may as well have brought in the lidar scanner instead. Or bought a robotic total station. 

So that’s where I need to figure out the automation: Turning each layer into a block with a different colour, and have the opening view a zoomed to extents bird’s eye plan of X horizontal and Y Vertical rather than Top/Right/Back Z Up, X down to the left and Y off to the right like Moasure defaults to. 

I like your suggestion for calling each layer A, B, C, etc. So that I can then have a routine that will assign them all colours when creating a block.  

I named them according to the main landscape feature contained. The Moasure app just defaults to calling them Base Layer and then Sub Layer 2 etc. So I will just stick with that. 

Thanks again to you both for your comments!