Hello members I had some topo Data and i want to rotate to real coordinate,anyone can help me for this work excel or any program helps to this......
This Content Originally Published by a land surveyor to Land Surveyors United Network
What Mr. Sattar said is true but I am not sure what you mean by "Real coordinates". That would depend on the reference frame you are converting from & the reference frame you are converting to. Geodetic elevations are usually referenced to the orthometric elevation but any reference frame, including "assumed" can be used if it satisfies the requirements of the job. If the topo data was obtained via GPS, there are a number of software programs that will do the trick & the US NGS likely has a free download that will also work. I have never had that problem as I have never had the need for a GPS topo but I have used GPS elevation data many times. Converting ground coordinates to grid coordinates or vice versa is a bit more complicates. For small areas there isn't usually a significant difference in the distance between coordinate values of the same type. Greater distances get more complicated as geodetic distances follow the curvature of the earth & take the convergence of the meridians (mapping angle) into consideration. Modern highway engineering generally involves adjusting coordinates with GPS observations every few miles. Several State DOTS have posted excellent discussions on their websites that are far better than any explanation I can give you. The Texas DOT is one. I also like the NGS products. There are also software programs that will get you close enough for most surveying requirements. Autocad won't do anything, it is a drafting (CAD) program. There are a number of programs that run inside of Autocad as well as a number of other CAD programs that will. Carlson seems to be the most popular.
I agree with Sattar
Points can be rotated in autocad by just selecting them and using the rotate command and a base point. Reference points between the 2 coordinate systems are important to get them lined up correctly.
Man try UCS command in Autocad and UCSMAN is another. THere is no need for rotating anything. Rotating has a downside in CAD as the accuracy is lost very often especially when there is lots of points. You see CAD has its downsides and this is one of them. When using UCS it works much more accurate. We are talking milimeters when rotating but still. Each time you rotate it will shift.
Above will apply to data on an area of max few kilometers wide.
For the roads or the data which covers longer distances you would have to apply corrections to cover for the curvature of earth. Mr CHARLIE B. AYCOCK, III covered it already quite well.
https://www.youtube.com/watch?v=9FrSD5ipSMI - around minute 2:00 it starts where he uses UCSMAN command - in portugeses but it does not matter
Maybe I misinterpreted the question. I thought he said topo data? Topo data is 3 dimensional. Geodetic measurements are curved, rectilinear measurements are in a straight line. Yes you can rotate objects & lines in CAD but the coordinate values can suffer. A better solution if you are working in Autocad is to use something like Carlson. I like PROCOGO, it is relatively inexpensive & runs in Autocad. Converting geodetic elevations to a local datum could be a bit sticky as our British friends might say.
It is not vey clear for what reason he wants to rotate it. I just wonder what kind of jobs can you do in Walterborough as a land surveyor?
Actually, I don't do much of any kind of surveying in Walterboro. Lately, I've been trying to downsize & am trying to target rural boundaries. If it is surveying, I've done it. Everything from large corporations like Robert Bosch to surveys for every branch of the military, even including one ship & a coast guard buoy tender. I've surveyed on most every military base in a 3 state radius. I also worked for the U.S. Forest Service & the State DNR. I probably should have stayed with the forest service, the DNR was a disaster. I think I am going to phase out subdivision work. The surveying isn't that bad but the regulators are out of control. FEMA is a disaster! I'm rooting for Trump, get'em Donald!! The resorts around here fed me for many years. I really hated surveying houses, especially those chopped up architec (sp) nightmares. I often wondered what I would do with one of those things if they gave it to me with all expenses paid! I am kind of fond of the natural environment & there are less complications & regulations living on a military base. I did make a lot of money laying them out & surveying for the contractors but I have no desire to go back. Time to downsize & reduce the level of stress. Mostly all I need to worry about is hunting season, when the tide is high & what's biting. BTW, I'm moving to Adams run which is a couple miles from about 3 salt water boat landings, one of which is just behind a large DNR waterfowl impoundment.
Very interesting and colorful life indeed. I love nature myself but where I live right now there is not much of it. I like Trump too and I am one of very few here who likes him. In fact I don't know anyone else...
Trying to downsize... this is very unusal remark I have to admit. Everyone in surveying business I know is really really tryin to go the other direction. :-)
Yes, regulations... cannot stand these people. They quickly develop the taste for power and want more and more while very often have little understanding.
Thanks Thomas, I don't look it or act like it, but unfortunately, I am 70 years old.
I realize that. Hats off to you Sir. I'm sure there is someone else though you can pass your invaluable knowledge and experience too. I wish I met you, or someone like you, at the very beggining of my surveying adventure for a mentor.
And yes - you don't look - I would give you 57 max. :-D if the picture is up to date.