Creating a shapefile from a Topology

[Anonymous]

I have created a parcel  topology of a city using a demo file from the Autodesk website. I would like an attribute table for the parcels. Is it possible to export this topology to a shapefile, so that I can fill in the attribute table?

[Anonymous]

Yes, you can either use the mapexport function or create a FDO connection to a blank SHP folder, create SDF from the topology and then "bulk-copy" the SDF to a SHP.  See the tutorials for more info.

[Anonymous]

Would you be able to give me some tips for creating an SDF from the topology? THNX.

[Anonymous]

Output tab -> Map 3D Export.  First tab of dialog box, "Selection" has a section "Select Polygon Topology to Export" - note you need to select "Polygon" at the top of this panel to enable the drop-down selection.  Click on "Help" from this dialog box for more information.

Does this help, or do you need more?

[Anonymous]

Note you can use this for either SDF or SHP....

[Anonymous]

That helps alot. While I have your attention, I was wondering if you had any tips for drawing cleanup. I have a parcel map of a municipality which is mostly made of survey data and the drawing requires major cleanup in order to make it into a topology. I've been using the drawing cleanup tools but I keep getting major errors when I try to create the topology. Thanks again.

[Anonymous · Accepted solution]

Hmmm - slippery slope down the bunny hole there....  there's the stock answer of "it depends...."

Having done a community parcel map before using ArcCAD (a E$RI 3rd party app on AutoCAD in the early '90s, which had similar tools, but a lesser degree of accuracy because the app used single floating point precision processing (8 significant figures) versus ACAD's double floating point (16 sig figs), drawing cleanup and building topologies drove me nuts...)

That said, first & foremost, save your work often - save out your source drawings / blocks of subdivisions and document the steps you take in a file like "DO NOT README.TXT" (gets attention every time...)

Step through cleanup actions methodically and build your map in a sensible manner - be that "from the outside in" of newer subdivisions to older or from city center/older developments out.  This can delve into a role similar to a surveyor where you'll need to think of your end as you start.  I.E. do you rubber sheet whole sections of your map for cleanup or do you honor rights-of-way at their platted widths, etc.  It really is a complex issue that separates a GIS from a Cadastral System.  I can't give you better advice on this other than talk to a "knowledgeable" surveyor.  Are you putting out a map as a functional document or as a schematic "cartoon"  I can't answer that one.

Then, work through a section at a time, you don't have to document every error & how it's resolved, but at least document your fundamental approach - what are your tolerances used etc.  Work through one step / cleanup action at a time until you can build your topology successfully and save versions of your work so you can always step back if you find you should have performed the cleanup in a different order or worked on a different section of the map first.  You might also bring in an aerial image as a backdrop to make sure you're in the right "ballpark" - I've seen maps get off by several hundred feet as the operator worked from plats from east to west and found he had a fictional plat that put houses & developed lots out in a river that he knew the parcels only went as far as the east bank.

You might split this out into a thread of its own for others to find and input their $.02....

[Anonymous]

I actually work for a land surveyor and am heading up their fledgeling GIS division. Your advice is appreciated. It is a large and complicated map of linework that is going to require some serious time put in. Will probably have to do it in sections.

[Murph_Map]

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@toddhepworth4253 wrote:

  there's the stock answer of "it depends...."

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Hey I got the copyrights to that anwser. LOL.... back when I was instructiing basic CAD at a tech college my students got used to that answer and started asking more complex questions.

[Anonymous]

Royalty check's in the mail... 😉

So, now that I have a few more moments:  My first encounter was with a city that had plats dating back to 1847, including some fun downtown sections along interior hotel walls to split out the kitchen as shared space with the adjoining restaurant.  Fortuantely, my 1-ft resolution airphotos gave me the building walls from the roofline.  Fun stuff.

I started with the City core, but I since found a school of thought that the exterior parcels, as recent surveys, may have better control & reliability as a recent survey product.  I could go either way, but it is really, really useful if you pick up some property corners/irons/monuments to control your map as you go. Then use your best judgement about linework in your source drawings/plats for which line to keep & what to delete if you have duplicates.  If the idea is to have relational information and create a "best availble document" you might be able to relax your standards.  I got hung up in trying to map the parcels ultra-accurately and didn't have a lot of functional product to show off for the investment that was made.  My situation was exacerbated because my partner, the municipal utility, expected a greater accuracy than what could be achieved with ArcCAD using full state plane coordinates versus a local ucs to accomodate the software's capacity for 8 sig figs.

I say get something useful asap and go for the most bang for your buck.  Make it functional and come back to refine after you have something running.  If your going for cadastral level work, be prepared to have a lot of hours of tedious work in front of you.

Best of Luck!

TdH