Section 127-158-3 - STANDARDS FOR SPATIAL DATA3.1Digital Parcel Standards Level IAll digital parcel files submitted to the Geolibrary must conform to at least Standards Level I.
1 The parcel maps must exist as digital vector data.2 The digital data must be a single data layer or file containing a seamless depiction of all of a town's property boundaries and other legal interests shown on the physical maps.3 The data must conform to the spatial standards as described in sections 3.6 and 3.7 of the Data Standards For Maine Geographic Information Systems, June 27, 2002. (appendix A)4 The data can be in digitizer units or real world units. If in real world units, the projection system, datum, units and zone if applicable must be specified.5 Annotation is not required.3.2Digital Parcel Standards Level II1 The digital data submitted must conform to the minimum specifications of Level I.2 The digital data must be georeferenced to as many well defined points as possible on an orthophoto or vector base data that meets National Map Accuracy Standards for 1" = 400 ' or better. Well-defined points are those that are easily visible on the orthophoto or vector base and that represent features easily identifiable on the digital parcel data. Examples would be road intersections, railroad to railroad or railroad to road intersections and the intersections of fence lines or stone walls.3 The digital data must meet all requirements of the Data Standards For Maine Geographic Information Systems, June 27, 20023.3Digital Parcel Standards Level III1 The digital data submitted must conform to the minimum specifications of Level II.2 The digital parcel data must be digitally recompiled to fit all coincident features on an orthophoto or on vector base data.A The orthophoto or the vector base data must meet National Map Accuracy Standards for 1 inch = 400 feet or better.B Property boundaries are often coincident with clearly defined and visible features. These include features such as stone walls, hedges and tree lines. When appropriate as determined by the map compiler, parcel boundaries should be registered as accurately as possible to features visible on the orthophoto or digital base map.C Roads should nominally lie completely within the rights of way shown on the parcel data. An exception to this requirement would be if in the judgment of the map compiler the street were not in fact built within the right of way or there are undeveloped rights of way or newly constructed roads for which no representation exists on the orthophoto or in a road centerline fileD Where discrepancies between adjacent town lines are more than the accuracy stated above, an attempt must be made to reconcile the difference. If the differences cannot be reconciled, then overlaps, gaps and gores must be separate polygons indicated as being "In Dispute".3 The digital data must meet all requirements of the Data Standards For Maine Geographic Information Systems, June 27, 20023.4Digital Parcels at Surveying/Engineering AccuracyIn Maine, the larger and more populated municipalities are likely to have some or all of their digital parcel data at a surveying and engineering level of accuracy. These are presented as a very high level of accuracy for parcel mapping, but not a recommended standard for the majority of Maine communities.
1 The digital data must conform to the minimum specifications of Level III.2 The digital parcel data must be located in relationship to cadastral markers. Suitable cadastral markers may include those sorts of features referred to in land records, such as deeds, survey plans, survey plats and other land surveying records which purport to monument or mark property lines or points geometrically related to property lines. The intent is to more accurately associate the parcel data with points that are directly related to the underlying land record information.3 The data must be referenced to geodetic control points of the National Geodetic Surveyor (or successor), the Maine Department of Transportation and/or points established by other parties using geodetic grade surveying equipment and methods.4 The data need not include every cadastral marker in a given location, but should include sufficient cadastral reference points to accurately reproduce the intent of the original land records used in the compilation of the mapping.5 To correct errors in the parcel data and to close lots geometrically, the available information"the bearing, course, and distance of parcel lines" will be entered into a COGO software system. This information is then referenced to cadastral markers.3.6Spatial Data FormatsAll spatial data files submitted to the Geolibrary must be in one of the following standard formats.
Autodesk Data Exchange Format (.DXF) A vector transfer format that has become the de facto standard for transfer of data between CAD systems. Arc/Info, ArcView and most GIS softwares will read and/or convert a DXF file. Arc/Info Export file (.E00) A vector transfer format, either ASCII or compressed into binary used to transfer files between different versions of ARC/INFO. This is preferred over submitting Arc/Info coverages. ArcView Shapefile. A vector format consisting of at least 3 types of files (.SHP .SHX .DBF) openly published and available for use by all GIS vendors. Coma delimited ASCII file. An interchange format for spatial data in which, for each feature, the unique ID number and corresponding coordinates are carried on a single line separated by commas. The feature attribute table is supplied as a separate file. MapInfo Interchange Format (.MIF). A vector transfer format, MIF files transfer graphics, MID files transfer attributes. Arc/Info will convert a .MIF file. Spatial Data Transfer Standard SDTS. A standard format used by federal agencies to support all types of vector and raster data. 18-127 C.M.R. ch. 158, § 3