C3d: Mapcheck Analysis with Curves...

I ran into this before,turned out it felt the lines are not connected by some minuscule distance. Zoom way in and redraw to try and find it, or draw a line beyond then trim it at the curve. Sorry, I specialize in ugly solutions

Thanks Curls.

Seems like since it is only using Labels for a closure, it would not be aware of any geometry...?

Also, just curious, in your experience have you found that you don't need to manually check the plotted tables if you have already checked the Labels using Mapcheck Analysis?

Thanks,

Steve

I have always had trouble with acad and curves in a closed polyline or parcel. I normally end up drawing the tangents and then a fillet between them. I think someone once posted that curves in a polyline where really just a series of connected very short lines anfd that survey figures actually had the geometry of the arc. it may help to create survey figure for the parcel but I haven't tried that because I hate working with them.

What you say sounds right, Robert.

I'm hoping I can get it to work, so I can avoid going blind checking a thousand table entries against the parcel report. If the tags close, I won't have to strain over the numbers, just the direction of the tag.

> I think someone once posted that curves in a polyline where really just a series of connected very short lines anfd that survey figures actually had the geometry of the arc.

That's only true of 3D-Polylines, which cannot have arc segments. 2D-Polylines have true curves. Feature Lines and Survey Figures are kind of a 2.5D hybrid, with 2D horizontal linework + elevations, and can also have true horizontal curves.

Couldn't tell you on the last bit, mostly because it has been awhile since I did one and even then it was only a couple.

I understand the concept (3D polylines being segmented around curves) and regular polylines (created from arcs) around curves are locked at a certain elevation.

But could you please elaborate on "2.5 Hybrid". What exactly does it mean?

Does it mean that the survey figure fully exists as 3D in the survey database but when drawn it's not exactly exactly it? Or something along that line?

:beer:

It's more related to the way the figure is defined.

A 3D Polyline has a set of vertices in 3D space. You can try doing an arc through any three of these points, but there's no way to represent something like a curved pavement line with changing grades in such a system. Or rather, you could get into 3D splines and such, but those are pretty complex, and do not create figures that form arcs with tangent line segments when looked at from the top (plan) view.

The "2.5D" approach lets you specify the horizontal information in 2D. Then the 3D information is "added" to the 2D layout. Basically, the feature is drawn in the 2D plane, using true horizontal curve info, etc. In other words, all the XY coordinates are calculated from true curve formulas, and form real circular arcs. Then the whole figure is "lifted" to the proper elevation, so each plotted XY point now gets its proper Z value.

If you look at a C3D Survey Figure or Feature Line in a 3D orbit, it pretty much looks like real life, with a 3D "squiggle" following pretty much exactly what the real pavement line does in real life. But when viewed from the top, you see nice, true arcs in the horizontal layout.

The limit with Survey Figures and Feature Lines is that you can only have grade breaks along the feature. The vertical data is then straight-graded between the grade breaks. You can't have vertical curves in a Survey Figure or Feature Line.

So in a sense, Survey Figures and Feature Lines are also like light-weight versions of Alignments/Profiles. Or conversely, the Alignments/Profiles are much like Feature Lines, except the Alignments/Profiles can handle things like spirals and vertical curves.

Thanks for the information, Richard

:beer: