Great open source GIS links here

Mapserver
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Fun stuff:

At Sandia GIS, we have created parcel map databases for towns and large western US counties (see figure 1) by digitizing old paper maps and using the relatively new (and very practical) Bureau of Land Management GCDB data files.

These GCDB files are an excellent, reasonably accurate and highly cost effective means of creating parcel and/or land ownership maps from scratch. You won't quite have survey grade data but you will have a very useful database that can be corrected easily when more accurate information becomes available.

Figure 1 below represents a large New Mexico county where we mapped approximately 50,000 parcels and 10,000 miles of roads. The entire project delivered a turnkey GIS database for a county with more than 4,000 square miles.

Fig 1.

We have a great deal of experience with both methods of data creation and heads up digitizing as well. Please talk to us before you begin creating your parcel map database as we have been down these paths many times and we can help you avoid a few pitfalls along the way.

If you have existing but inaccurate parcel information, Pixxures' Lineworks application might definitely be a solution for you. The process uses imagery to correct spatially incorrect lines WITHOUT changing topoly!

Some states require a uniquely created id number for the centroid of each parcel (see figure 2). We have dealt with this requirement in the past and have custom coded small ESRI applications in those instances. This is a vast improvement over your mappers having to guess the geometric center of oddly shaped parcels or overlaying a plastic grid to 'get close' on the parcel id number. After editing splits and combinations, your mappers simply run the small program to update the internal software information and recalculate the centroid and resulting parcel id number.

Fig. 2

If you are creating parcel maps from scratch, this is another instance where small details can mean alot farther into the process. This would be a great time to capture details for each parcel such as zoning or land use. We have built data, including field work, for land use analyses as well. We will work with your planners or GIS staff to compile an accurate and functional land use classification dataset based on our previous work for data collection in the field or simply field checking unclear information gathered from satellite images or out of date orthophotography.

Regardless of your method for parcel map creation, we can build a dataset for you that will be highly functional and not cost a fortune!