New to the board. Using tds survey pro with nomad and topcon gr3. How can I run grid (state plane) north but output ground coordinates? Thanks
Go to Survey > Projection > Mapping Plane Ground.
My answer would be you can't, or maybe you shouldn't. If you need to do that do after you download and do it in CAD. Another option would be to do a localization.
Thanks so much. I will try.
I do this. Once I get a mapping plane ground solution, my GPS distances match very closely with my EDM distances.
I run grid directions and ground distances in the field. I also figure out my grid/geodetic rotation angle to know which way "north" is when I key in a deed direction and distance to go look for points. I rotate to geodetic back in the office for my final map.
> I rotate to geodetic back in the office for my final map.
So, which way is north, for your final plat?
Geodetic?
Which way is that?
Especially, if you move your base, several times on that job?
N
tds survey pro grid north with ground distanceb
I am a "flat lander." Most of the terrain around here in Northeast Mississippi varies from nearly flat to gently rolling.
Almost all of my work is within a mile of my base station, so I usually pick a "high" point out in the open somewhere near the center of my survey. Most of my work consists of property boundary surveys ranging from a lot survey to less that 400 acres, so one base setup is all I need. I realize that geodetic north varies with an east-west distance, so I get one point for a base station setup near the center of my job site and call it "good." I run an opus solution to compare to my RTK network point and have found the two points to be close - ranging from a few hundredths to maybe around one tenth. That will not be good enough for more precise work or large jobs that require multiple base setups and least squares adjustments.
I work primarily on rural boundary surveys where pinpoint accuracy is not required nor feasible. Our Technical Standards require Class "D" survey closure to be a minimum of 1/2000 with distance accuracy +- 0.10 feet and the accuracy of a bearing to be +- five minutes. Our Class "A" survey closure is 1/10000 with bearing accuracy +- 1 minute and distance accuracy +- 0.03 feet. It appears that the differences between Grid -Geodetic - Ground are within tolerances for Class D, C, and B surveys no matter which is used. Typical grid-geodetic rotation angles for me are around 5 minutes, and grid to ground scale factors are "four zero's and some numbers." Differences are minor for small areas.
From my base station setup, I look at my convergence angle from grid to geodetic. I usually work west of the central meridian of the Mississippi East zone of the SPC, so my typical rotation or convergence angle is negative when going from grid to geodetic. Trying to figure out how to do that drove me nuts when I first started using GPS only 2-1/2 years ago, so I still consider myself an "advanced novice" in the GPS world. Thanks to others in this forum, I have learned a lot, and I am still learning.
I remember reading a paper from the NGS website that True North = Grid North combined with the rotation angle and the LaPlace correction factor, and that in general, Geodetic North is close enough to be called True North. For boundary surveying, I feel that holding to "true north" will more closely match or correspond with historical record directions. Mississippi allows grid north on boundary description, but only if the basis if bearing is clearly stated on the survey plat and is able to be reproduced by future surveyors. Since we do not have plat recording laws, that information sadly remains on the plat that is in the owner's possession and the surveyor's records. If the surveyor incorporated into the boundary description the required information telling the future retracement surveyor the parameters of the survey data, then all would work well. Most of the time, this information is either stripped out of the surveyor's description or was never put there in the first place. Therefore, my work follows the common in-place system of "true" directions and ground distances.
I still do a lot of work with my total station for points not in ideal conditions or locations for GPS shots. Knowing when to switch from GPS RTK to EDM is only learned by experience, knowing your equipment limitations and greatly assisted by reading posts from knowledgeable people on this board and talking to fellow surveyors. I gain more experience each time I go to the field, and refine my methods and techniques with each experience. Thanks to you guys, my knowledge increased at a faster rate and saved my %#^* from making a few and "should have been obvious "dumb mistakes.
I am open to comments and suggestions and recommendations or clarifications. Flame on!
tds survey pro grid north with ground distanceb
Not to flame...
But, I like leaving it on GRID brgs.
If I need to use anything else, I show how to GET TO GRID.
ie, "For Arkansas State Plane Grid Brngs, Rotate the bearings shown on this plat Clockwise 0°14'32""
This makes it so ANYBODY can reproduce my bearings.
Whereas, if the base is 1 mile East of my survey on one day, and it is 1 mile west of it on another, well, we have a difference of around 54-58" per mile, of EW change, around here.
Thats just me.
N
tds survey pro grid north with ground distanceb
Good point. I leave all of my survey pro jobs in state plane coordinates. When I get to a new job that is nearby or a mile away, I open up the old file, set a new point, run another opus for comparison, and use that base station for a new rotation point.
My reasoning is that since true north converges at the poles, the two Norths are not going to be parallel. Even when using solar observations a mile apart, they will be different by about 50" for me. Therefore, each survey, within reason, gets its own "true north." I can see problems with this method, though. One day, if I " fill in the gap" between two surveys, I will have a different bearing. However, if I follow my standards for rural surveys and report my bearing out to the nearest minute rather than seconds, I can "lose" the difference in the round off.
I see a greater benefit is using only grid bearings for consistency between surveys. :-/
tds survey pro grid north with ground distanceb
>
>
> I see a greater benefit is using only grid bearings for consistency between surveys. :-/
I do too. The unnessary confusioin, that developes, over the yeers is not worth it.
perdee soon, wen enouf stufff is hangingoutallover, it getss hard to fugger out what huppened.
What about the next person to get in your computer, and use your studffff, when you retire?
N
tds survey pro grid north with ground distanceb
"What about the next person to get in your computer, and use your studffff, when you retire?"
May God have mercy on them!!
Harold
Would you happen to know the title of that paper? I would like to read it.
I am not too far from your neck of the woods. I am always trying to improve my methods, and do the best job possible.
Harold
I found it at the following: LINK
It is entitled "What you need to use the State Plane Coordinate Systems" by the NGS.
However, the link carries you ayresriver blog site for a downloadable PDF file.
> New to the board. Using tds survey pro with nomad and topcon gr3. How can I run grid (state plane) north but output ground coordinates? Thanks
OMG. This will get people talking. Try letting your DC calculate based upon your measurents.
Its like this for me. The job is in state plane but I have to layout ground distances. Even though I am a flatlander I still need everything to fit within a mile.
Most data collectors have this function if you know how things work.
I told survey pro to stake out grid coords but apply a factor. I set the gun up and shoot about 3,500 feet and the hard dist matched the calculated ground distance even though I staked grid coordinates. I should have found a 0.25 ish difference but the DC did what it was supposed too and I hit within 0.02' of what I calculated by applying a combination factor to the grid.
:good:
Harold
Thanks Harold.
I was hoping to be able to make it to the Mississippi Conference this year, but it is not looking like my schedule will let me. I was hoping to get to meet you in person.
Maybe next time.
You can look at your raw data file and see that survey pro calculates a ground scale factor at the instrument position and applies it to the grid distance to get a ground distance when you are working in a ground mapping plane. It is pretty slick, and I wish I knew much more about what all goes on inside the software.
I have downloaded the user's manual and a reference manual for the software, and have done a lot of reading. Trimble has a utility program that converts a .survey file into several different file formats, including a modified version of the raw data file. I searched this site and found a post that led me to the Trimble site for the free utility software download. I had a hard time trying to read all the raw data on the little ranger screen. You will be able to see in an expanded format the factors applied and most of the raw data file.
What is your reasoning for rotating to geodetic for the final plat? I personally try to make all my final survey maps referenced to State Plane Grid North so when I tie surveys from several miles away, the bearings will match. If I have to use Astronomic North on my final plat, most of the time I will give the lat and long of the observation point so any surveyor down the road can get my bearing basis real close. The reason I want to start out my job on State Plane Grid North is because if I use Astronomic North on my data collector and then rotate in the office and calculate some stake out points, I have to rotate back to Astronomic North to send to my data collector for stake-out. That leaves a possible error if you are in a hurry and forget to rotate back to Astronomic North. I am not stuck with "DOING IT THE WAY I HAVE ALWAYS DONE IT". I am open to others' opinions in hopes of providing a better survey. Thanks for all the feed back to all.
MB
tds survey pro grid north with ground distanceb
OK. After reading your post again, I understand your reasoning for using Geodetic North. Thanks.
MB
Mark, you are correct. All that rotation stuff has to be carefully accounted for. I use geodetic in the office to plot deeds on top of my coordinates. Some deeds are DMS, most are DM and others are "run thence in a southwesterly direction back to the point of beginning," so I have room to play on some deed calls.
In cad, I dump my points and import. Then I use the OPUS point to draw an ortho line grid north for 1000 feet and assign a point, usually #99. I then look at my projection calculation and find my convergence angle, say -0*05'32". That is the geodetic azimuth of grid azimuth 0*00'00" in my usual haunt of west of the central meridian. I double check using survey pro and do a COGO-point in direction with a grid azimuth of 0 and distance of 1000'. Inverse between base and 99 to confirm grid north 0 and grid distance of 1000'. Survey pro also gives you geodetic azimuth and horizontal distance ground. When I first saw the screen on this calculation, it blew my mind.....there were THREE distances on that screen! I had to study up and find out the difference between horizontal distance (found out that this was just grid distance), horizontal distance ground (should = EDM horizontal distance) and geodetic distance, which is an arc distance on the ellipsoid, I think. See, I am still learning!
I then draw a line with the bearing using the convergence angle with a distance of 1000 feet and use cad text to label the line end points GRID and GEODETIC, and type in the rotation angle to see on screen next to the points. When I rotate, I use my software, but I have to remember that autocad considers counterclockwise positive, which is why I use the visual indicators in a cad layer called "rotation."I wanted to see that my software rotated the points like I thought I had told it to! Point #99 will either be resting on the end of the grid line or the geodetic line, so I always know what my coordinate system is on my computer.
I then rotate my survey to geodetic, plot my deeds, work out my survey, assign new points, and then rotate back to grid and upload the new points to my field controller for stakeout. Simple? Not really. Visually, I can see what I am doing on my computer. In the field, which way would you rotate a deed bearing to get a grid bearing to go look for a point? My head hurts to think about it. Most of the time, I just COGO in the deed calls in grid and that will get me close enough to search with my trusty Schonstedt. One trip surveys are rare, and if I get one, it is grid all the way. I rotate the final plat to geodetic.
This is probably not the best system to have, but it works ok for me. My computer software is capable of handling state plane coordinates, and my line annotation routines are capable of labeling with either grid or geodetic with applied scale factors while using the great advantage of maintaining only one coordinate system and no rotation of any points. That is my next "gotta learn" item. It would make life much simpler and not generate headaches. There are much better ways to do what I am doing. :-$
For land surveying, I see a great benefit for going grid all the way. As an engineer, direction is not nearly as important as ground distance. It is imperative that ground construction distances (horizontal distance ground) must exactly match with points laid out with GPS. You may want to explore the possibility of a low distortion four corner box around your project that has been surveyed in with a calibrated total station and EDM and then adjusted, and then developing a projection and scale factor for that area. I have read other posts on this site that advocates this method for engineering projects that puts a low distortion plane of projection at or very near the project surface area.