Objective: Collect elevations on a perfect 100’x100’ grid as quickly as possible. (Perfect in this case and drawing scale would be within 5.00 feet of the grid intersection point).
If you are doing a topo of a totally flat 40 acre open field (rectangle more or less) and the client wants it on a very tight 100' grid, What method(s) do you use to get your shots as close to the grid as possible?
I am planning on using my golf cart to drive this particular topo with my rod mounted to the side, and My TDS Ranger mounted to the steering column. I have used the following procedures in the past, but I am looking for other ideas and procedures for something possibly easier & quicker:
• Using the "offset staking" routine in TDS, I would pic two points for my baseline (say the SE corner of property as 0+00 and the NE corner of property for my baseline) and stake each grid point within a few feet, then record the shot. (This method is somewhat slow in that there are a lot of keystrokes, and you have to come to a complete stop for each shot).
• Set lath at the 100’ intervals along the north and south property lines. Starting at the SW corner, I get the first shot and remove that lath. Then I set my ranger to record shots at 50’ intervals (Just in case there may be a bad shot), aim the cart at the lath at NW corner, and drive to the north. When I get to the NW corner, I take the last shot manually and pull that lath. I then repeat that procedure for the next line driving south and so on. (This method requires setting a bunch of lath, which does take some time, plus each lath has to be flagged and painted in order to see them clearly from approx. 1300’).
• Set the ranger to record a shot every 15’. I then drive back and forth, saturating the project with elevations, and sort it all out back in the office. (This method is by far the quickest field time, but produces a ton of points and takes a bunch of time to clean up the drawing, with not the most favorable results).
Looking forward to hearing how you might attack this situation and all your ideas!
I would set up a grid in the data collector and stake out those points.
an option may be to topo a rough grid, pick up all the break lines, then create a DTM with a 100' grid.
I was thinking the same as Joe.
Most data collectors have an auto topo routine were you can set the interval say 25' or 5' and it will shoot those intervals on its on . I use it for roads or fields with prism pole on a wheel or 4 wheeler .
Even better shoot the topo tight then Carlson will allow you to spot elevations on a grid if you like in the office at any interval based on the DTM Model.
For similar work, I have used the "stake to line" procedure in TDS. Set up a base line somewhere on the job and watch the station and offset. Once you reach the right spot, just store the point. Doing a 100' grid makes it easy to tell when you've got the right position. The only drawback is, when you do this, TDS does not store the angles and distances to raw data, only the coordinates of the stored point. You might put out some stakes or pin flags once in a while to help stay on line. Once you get the feel of it, it goes pretty fast.
In the Leica 1230 I can look at the current rover coordinates, so I just walk to the coordinate I want (like 825N & 275E) and take the shot. Gives me a perfect grid and a really nice drawing.
:good:
Would add breaklines.
I would do the same as Joe. However, it would require software capable of this function.
What I typically do is pull down the longest two sides of the property setting tall lath with alternating flagging at the required interval, matching the color of the flagging at the respective ends of that grid line. If they're far away and hard to see I take some compact binoculars to keep me on the proper line and simply pace each 100'.
Works like a charm, 40 paces at a time!!
I should note that if it's an odd shaped property I'm careful to lay out the grid lines such that a true "square" grid is maintained.
I don't know your client or his reasons for such exacting grids. The reasoning behind the client's wants may exceed his needs.
Some old school reasoning and antique programs require exact grids for them to function properly.
Have a casual conversation to get with his reasoning and it may be to his advantage to let you make the call for best procedure to give him what he needs.
It reminds me of an old saying:
Cheap work is not good
Good work does not come cheap
Certifying exact work may be beyond your budget.
Since the land appears to be of nominal slope, you could compute an exact digital coordinate grid and assign near enough locative elevations to that digital data.
Steve - I noticed that you are using Topcon GPS. If you have a collector with Topsurv on it you can create a grid that you can use in map mode to collect the points. You give it two points on the site, tell it the size of the grid spacing and it overlays in map mode.
We have used this on hundred plus acre sites very successfuly. The beauty of it is you just walk the site and see where you are on the screen in relationship to the grid at all times. None of the points we collected were farther than 3' from the grid points.
As others have mentioned, it is far more important to hit the grade breaks but we still use the grid to make sure we did not miss large areas.
I use Survey Controller and the "Stake Out Line." Just watch the Station and Offset to keep track of where I'm at. Just finishing a reservoir topo where the bottom 12 feet of the lake (80 acres) needed to be done because there was water in the lake when an aerial was done 19 years ago. So I added elevation to the end points of the statkeout line (nearest even number above the original water level). Then I watched the cut or fill to keep me under the original water surface. It finally worked the best to just walk the contours sort of like breaklines only picking points as the contour curved around staying near the contour elevations I needed. As I went then I picked up other features (breaklines) needed to make the contours or DTM come out right. I worked out fine, good hourly money, just boring as heck after many days. The muddy bottom of the lake wasn't all that fun either.
I topo alignments (roads) the same way. Input the alignment and then Stake Out Alignment. Watch the station and offset and take your cross sections where you need them. Pick up whatever else you need as you go along.
I did similar to Gregg last fall. I just uploaded a CAD background file, and when walking with the DC, I was in map mode. Just stop at the apparent grid intersections, and it worked well. Also did it with the 4 wheeler, and it worked great too. Staying on-line was easy, remembering to stop every 100' wasn't. Had to jump off several times and walk back a few paces to collect the missed shot.
I would take the shots per coordinates, using the data collector somehow, and leave that golf cart on the trailer. Should be easy enough staying on coordinate with even 100 values.
This seems to me to be "old style surveying". It's what we used to do when we would stake out the grid points, set a hub, then come back in with a level.
I have no idea why anyone would do that these days, with the technology we have. It sounds to me like the person who wrote your specs has no idea of what Surveyors can do now.
You get a FAR better representation of the land if you just shoot breaklines with a total station. Grids are so ancient. And if you have one of the neat new scanners that shoot 1M/shots/sec, you have even more options.
> I would set up a grid in the data collector and stake out those points.
If by "set up a grid" you mean to load a spatially correct dxf with grid lines showing, then navigate to the intersection points by watching the moving blip in the map screen, and taking a shot when I get close, I agree. That is how I would do did, and that is how I have done such things.
I'll walk it stepping the distances off as I go. If a hole shows up at the end of the day, I'll go get more shots. I'll also get all those nasty break lines, even though the apparent specs don't mention those.
If the client has to have them at exact stations, I'd have to ask if he's heard of AutoCAD or some other contouring package as it hasn't been necessary in the last 20 years to get exact stations.
If he balks at that, I'd then as him to send me the paper work where I can be his employee because as a contractor, he doesn't have that control over my work product.
Not exactly - I would shoot whatever points are needed in a rough grid by pacing, being sure to locate any break points/lines. once field work is completed, use software like Civil3d or InRoads create a DTM of the surface, then create a grid extracting the elevation/location at whatever interval you need. Similar to creating cross-sections from a DTM. For ground shots, we usually truncate elevations to the nearest tenth, so if your DTM is done right, the elevations should be good. There is no reason why you should need to stake-out to a grid point to shoot the elevation exactly there - let the modeling do it for you - much faster.
I'm not exactly proposing to "stake out" ponts, just to follow a blip on the screen until I get within spitting distance. Of course, while I'm doing that I also count my paces, etc. Then I'll build a DTM surface, and I might report elevations on the theoretical grid, if the specific circumstance called for it.
