Grid Linework w/ Ground Stationing in C3D

Its been a nagging thing for me also. To date we usually just stay in state plane. We are lucky, our scale factor is very close to one, for example 0.99993. So most of the time we just ignore it. For boundary surveys, I usually show ground distances and just do the math for each distance.

I'm a little fuzzy on this since its been a while since I've done it, but the transformation in C3D does work. The only problem is you end up with 2 sets of coordinates. You have the screen coordinates, which are for ground, then you have another set for the same point which would be state plane coordinates. We had problems sometimes when we would upload coordinates to do stakeout grabbing the wrong set of coordinates. If you would list a point, it shows both sets of coordinates, you just have to grab the state plane coordinates when uploading. This might be the best solution for you.

With our area having a scale factor close to 1.00 I have chosen not to do anything but work in state plane and leave the drawing that way. It doesn't affect quantities enough to even worry about on engineering projects.

I like being very close to 1. I have not had to address these fuzzy issues, but I do have others.

We're in the same boat with combo factor near 1. The only time this really becomes an issue is when the engineer dimensions and/or adds labels. They measure a half-width on large r/w and it comes out to .02' shorter than the label we have dimensioned (ground dimension for re-creation purposes and comparing to record).

I found another solution...when dimensioning, modify the dim style, primary units tab and change the scale factor. For labeling, there is still the expression tool where a scale factor can be added. From what David said, it seems like transformation tab scales coordinates. This is all great, but what there needs to be is one command to do this all. We all know how Autodesk is like the blackhole when trying to advance survey relative programming.

When I state "scale factor", this means combination factor in survey terms. Scale factor the term used in Civil 3d.

Also, when calculating boundary lines I want to be able to type in ground distance and the grid distance linework to be drawn. And then when labeling, label in ground. This is for ease of corridor type projects and multiple miles in length.

Can you explain a little more on getting the scale factor to be applied when labeling and dimensioning?

I've searched multiple forums and haven't found an answer to give me that warm fuzzy feeling yet. At this point, in 2015, I have to assume Autodesk has addressed this and came up with a solution (not using roundabout ways to get answer).

Short answer - "NO."

Longer answer - "kinda sorta...."

First some background. The AutoCAD platform that Civil3d is built on top of was originally created as a Mechanical drafting tool. The base level coordinates used inside of all drawings are a Cartesian system where every location has a real world x,y,z value and all distances are assumed to be real world measurements.

Somewhere around 2001 Autodesk started producing their Map software. The assumption made there was that all coordinates in the drawing would be Grid values and all of the measurements would be grid distances. The Map software includes tools for translating spherical coordinate data to Grid, and for translating from one grid system to another - NAD27 to NAD83 for example. Map is intended for GIS work and doesn't have tools for importing survey data or scaling coordinates to ground etc.

The Civil3d development team chose to use real world coordinates as their base platform. Civil3d assumes that the x,y,z values in the drawing are equivalent to real world N,E,Elev values and it calculates distances etc. internally with the assumption that everything is at ground scale. Civil3d is designed to work on top of the Map platform, and C3d includes tools that allow you to link to the Map database of coordinate systems. C3d also has the ability to apply scale factor and translation to coordinates as they're being imported, so that your grid data from the field can be adjusted to ground for use within the drawing.

So - if you have built a drawing using grid coordinates, but you didn't set up the coordinate system or the Transformation settings first then Civil3d is assuming that everything you're doing is ground coordinates. This really doesn't matter to you, until you start trying to apply scale factors to things after the fact. The other problem you have is that alignments are assumed to be 2d geometry with real world length, and there are no options that I know of for scaling of stationing.

Edit - I have a somewhat better written explanation http://forums.autodesk.com/t5/autocad-civil-3d-general/coordinate-transformation/m-p/5431085/highlight/true#M263285&apos ;">here.