View Full Version : Parcel Best Practices
2007-10-23, 07:24 PM
I am new to Civil3D, fresh out of basic training!!! I am looking for some Best Practices. Why reinvent the wheel? My issue, I am creating parcels, basically for the entire site. I have a multi-product residential area that I need to subdivide, some lots into single family, and others into multi-family. What comes first? A parcel for the entire site, then the lots, then the wetland areas, lakes, etc. Or... do I just create a parcel for each lot?
Thanks for the tips.
This is a loaded question.
Parcels are really not designed correctly in Civil-3D, so there's no real good way of doing it. You basically do what you have to.
In theory, you can do everything in one giant Site. Every lot, tract, piece of ROW, etc., are all Parcels in that one Site.
However, in practice, that often doesn't work. And since it is impossible to create Data References or Data Shortcuts to parcels, it can turn into something of a nightmare.
There are a lot of posts in Autodesk's DGs about this. You should also check out some of Dana's posts on the subject, such as this one:
Dana also wrote some posts on "the Art of Span" that goes over Spanning Labels, but I'm not sure offhand where those are - probably at Civil3D.com.
This is an area that you'll have to fight through. Start with the basic post on Parcel Rules I gave the link to above, then search Autodesk's DG and Civil3D.com, and read everything you find. This will allow you to ask more-focused questions about what to do next, because you will certainly have more questions.
2007-11-27, 01:17 PM
After some land planning projects done partly with C3D I have some ideas about what to do and what - not to do.
1. As mentioned in one of C3D "Parcel Rules" like page - don't mess with creating Parcels from closed polylines, otherwise you will kill yourself. Truly. I had one big plot which was subdivided into 65 small plots. I thought that boundary map of big plot definately is something that will not change, ang created it from closed polyline. Literaly one day before finishing project manager came and told that there is new, more precise boundary map. And I had to re-parcel all of 65 parcels. If in calssic AutoCAD you can do something with parcels if they are closed polylines (get areas), then in C3D make it as simple as possible - only 1 lot line to define border between 2 parcels, big plot boundaries as simple lines.
2. ROW command is absolutely waste. Because there all the time will be changes. If alignment from which previosly are made parcels using ROW command is moved, those parcels will not move with alignment.
3. I tried to use 1 Site with those 65 parcels as background for other maps but had difficulties. One issue is draw order of hatch pattern (if turned on) is over lot lines. If I want to see lot lines, I have to select all parcels and use Draw Order/Bring to Back. If I do this and have small enough parcel who's lablel goes over it's boundaries, those parts of label which goes over boundaries ar displayd under neighbour plots' hatch. Looks ugly. What I do, is to make 1 file with actual version of parcels, then export it to AutoCAD and work with classic AutoCAD objects.
4. C3D can't solve more complex issues (I have posted 1 previously in this forum). It is very effective if conditions are quite simple. If you have project with blocks of plots and streets all around them, then it will be tricky.
For you I'd suggest to create 1 big parcel (mother parcel) )from lines, then create parcels from objects about which you know surely they will be there, then create other plots. Before you start, create parcel styles and label styles you will use. Single family, multi-family, wetland areas, lakes, roads, etc.
Not sure what you mean by you "had to reparcel all of 65 lots"...
There is actually a significant amount of editing that can be accomplished with Parcels. However, it is pretty convoluted editing. Autodesk desperately needs to redesign and reimplement Parcels from the ground up, but I think the existing functionality is more-complete than you realize.
For example, not sure what you mean about closed polylines. I have used them frequently with no more problems than any other linework. However, you must be sure that you do not have any duplicate segments in the linework. If you are referring to what I think you are, then the warning about polylines has to do with this. As one example, sometimes you may get parcel linework "from others". Sometimes, we get stuff from others, and there may be lots of duplicate linework in the drawing. If you select all this linework and try to turn it into a polyline, you may get segments that overlap, as Autocad tries to create a continuous polyline from all these duplicate segments. In other words, you may get a polyline that goes from Point 1 to Point 2 to Point 3, then back to Point 2, then to Point 3 again, then to Point 4, etc. This will create nasty surprises if you try to create parcels with it.
Another way you can get into trouble is if someone created Land Desktop parcels somewhere along the line, then did that "Create closed polylines from parcels" thing in Land Desktop. This will give you a TON of duplicate linework, and trying to use this linework to create Civil-3D parcels will lead you to trouble. (Map cleanup tools can get you out of it, though.)
After that, there are some basic rules to remember. One of the most-important ones is that all vertices in your source linework become "frozen" PIs. A "frozen" PI cannot be deleted using the "Delete PI" command, and spanning labels cannot span a "frozen" PI. If you need to delete a "frozen" PI, then you must use the Delete Subentity command to delete one or both segments on either side of the PI. Then, if you only delete one segment, edit the remaining segment to span the gap. Or, if you delete both segments, redraw the entire stretch as a single segment.
Also note that you can draw segments using the Parcel Edit Tools, or you can simply draw them using normal lines, arcs, and polylines, then use "Create parcels from objects" to add the new segments to the existing Parcels. For some situations, it's easier to draw the linework with normal Autocad commands than it is to use the Parcel Tools.
And don't overlook the Subentity Editor. If you grip-edit a curve segment in a Parcel, you may notice that it loses its radius. However, you can fix this in the Subentity Editor. After grip-editing the end of your arc, turn on the Subentity Editor by clicking the button in the Parcel Tools toolbar. Then select the segment you want to edit using the "Pick Subentity" button, also in the Parcel Toolbar. Now you can edit the segment radius in the Subentity Editor.
Of course, once you start editing Parcels, you'll discover that it's something of a mess.
The big thing is that editing a Parcel often causes C3D to delete and recreate it. In the process, it loses all custom data - i.e., the Parcel Number and Style will get reset, the Parcel Name (if you gave it one) will be lost, as will things like Parcel Description and any UDPs you may have given it.
And your labels may get messed up. It's not uncommon to see labels reset on other Parcels in the same site, and not just the adjoining Parcels. Sometimes, editing a Parcel on one side of the Site will reset the labels on Parcels all the way across the Site. Parcel Area Labels are the worst, but sometimes there's problems with the Segment Labels as well.
Parcels are really one of the weakest areas of Civil-3D. There are no tools for analyzing Parcels, and finding/fixing overshoots and gaps, like there are for Map Topologies. Parcels can't be grouped, and Parcel Numbers cannot be reused in a Site, so you may end up needing to follow convoluted procedures if your area likes to use Blocks in subdivisions. It is also impossible to create Data References to Parcels, which turns everything into a giant nightmare for Surveyors.
Another weakness is the lack of integration with Map. Map Topologies provide awesome capabilities, but there is no way to convert a Map Topology into a Civil-3D Site. Map Cleanup tools can still be useful for cleaning up the linework before creating Parcels, but they have to be used very carefully, in order to avoid breaking all your Span Labels.
It isn't fun. But every once in a while, you'll be able take a couple of hours and do something that would have taken a day or two or more in Land Desktop. So it ends up being something of a push. Parcels are a mess in C3D, but they aren't so much of a mess that Land Desktop starts to look attractive. They definitely reduce the appeal of C3D for Surveyors, though.
Would you mind, at the least, turning your CAPS LOCK off?
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