Hello,?ÿ
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Different Stations from Data collector VS Cad / Math
I am new to the Forum and new to Surveying. I provide guidance services for directional drills and we are required to do topo for the length of the project as well as survey existing utilities, River, Lakes, Etc.?ÿ
We currently work with a Trimble R8S with TSC3 Data Collector and R8S base.?ÿ
For the most part I work with RTK. I will set up the base on a given control point for the project.?ÿ
My question is why do I get a different Station number from the data collector than if I calculate it with calculator or excel and CAD LT and or Civil 3D
My calculated points measure the same distance as if I put them into Autocad but get a slightly different length from the data collector when I view the Northings and eastings as Station and Offset.
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I apologize now if I am not explaining myself correctly. Surveying is new to me and I have just been thrown at it.
One possibility is that distance calculated from northing and easting (x and y) will be a two dimensional distance, but in AutoCAD if your points are three dimensional (x, y and z) and you use the DIST command to measure distance and snap on the points, the distance is likely to be three dimensional.
I am only use Northing and Easting in AutoCad LT. This should be two dimensional. Same as if I calculate it manually, or NO?
I thought maybe it was the Data collector that calculated 3 dimensional but after speaking to a veteran surveyor he said I should trust the Data Collector.?ÿ
on approx 500m the difference is only about 13cm but I feel like it should match.?ÿ
Yep, sounds like one is 2D and the other is 3D. Should be easy to figure out. On the DC software that we use it can calculate in both 2D and 3D. Suggest you put two 3D points into AutoCAD and get the 3D distance and compare to the DC distance.
This was my theory all along. I will try to compute these points 3d in Civil 3d.?ÿ
For just collecting topo and surveying a few hotlines and a rivers edge etc and working in AutoCad LT 99% of the time should I be changing a setting in my DC to give me this in 2d? I will have to explore more with the TSC3 to figure this out
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Thanks again for all the help
Are you considering that GPS (grid coordinates) are shorter than surface coordinates. So if you are calculating stations in CAD and plugging them in your GPS your coordinates are going to be different.?ÿ
I just looked and the Jobs in the Data collector were set to Ground for COGO. If I change it to Grid the Station Differences are now a match within 0.001. It does still seem to be out that 0.001 but that little bit will not effect what I do.
There's going to be a little difference depending on the rounding applied to the scale factor. It is tricky and it can bite you in a long alignment.
You probably just answered your question. The points in ACAD are on some grid system. Those in the data collector are as well. When you ask for ground distances that's what you get. The coordinates aren't changed, just the expression of the relationship between the points.