The fees for the data are charged for all parties except for the following: Federal, State, and Local Government Entities, Educational Entities, and any contracted parties working on projects for Howard County Government.
This data is part of a public CD product that is available at the Howard County Central Services desk. Please contact the contact person for more information.
The fees for the data are charged for all parties except for the following: Federal, State, and Local Government Entities, Educational Entities, and any contracted parties working on projects for Howard County Government.
This data is part of a public CD product that is available at the Howard County Central Services desk. Please contact the contact person for more information.
This data should be used based on information listed in the purpose section of the metadata. Also, users should use the data within the limits of its temporal accuracy and source scale.
A contractor was hired in 1999 to rubbersheet the inaccurate 1:7200 scale cadastral layer maintained by Department of Planning and Zoning to the more accurate 1:2400 scale 1998 orthophotography. Some 1:2400 scale or better already existed and automatically replaced the less accurate cadastral layer. Then, the less accurate cadastral layer was rubbersheeeted to match visible lines of possession as viewed on the High Resolution, 1:2400 scale, 1 foot per pixel Orthophotography. The processes was used in the following tax map areas; 1 - 5, 6 - 10, 12 - 16, 19 - 23, 27, 28, 32 - 34, 38 - 40, & 45. The original low accurate Cadastral Layer was in NAD1927, but was converted to NAD83 before it was rubbersheeted. The low accurate cadastral layer was created in Microstation software. The rubbersheeting was performed using GeoMedia Proffessional, but was done so withougt changing the format of the data.
The rubbersheeting project was produced in phases of about 4 or more tax maps per phase, depending on parcel line density. Following the completion of a "phase", the contractor delivered the data to the GIS Division. The GIS division immediately did quality control the data. The QC was based on a "pass/fail" system. The GIS division extracted a random 10% of the parcels in the phased and checked the linework for accuracy and completness against the existing high accurate 1:2400 scale data and the orthophotography. The data was to also meet the strict guidelines of the contract which also included that the square foot area of the newly rubbersheeted parcel be within a certain percentage of the old less accurate data. The low accuracey data was not spatically accurate, but did have accurate dimensions. Therefore, the rubbersheeting was not permitted to change the area of the parcels by more than a few percent. The random 10% tested had to be 100% correct for the phase to pass acceptance. If the phase failed, the errors were printed out on paper and delivered to the contractor to be fixed. The contractor was to also note the type of error to occur and look for similar errors on the other 90% of the phase. The contractor then delivered completed phase to the GIS Division, where corrctions were examined. The GIS division then selected another random 10% of the phase to be Quality Controlled. Again, the sample had to be 100% corrct for the phase to be passed, if errors were found, the process would start all over again untill the random sample was 100% correct and fulfilled the requirements of the contract
Because the remaining phases of the rubbersheeting project were dense, the GIS division decided it would be more cost effective and time saving to finish the project "Inhouse". Also it was discovered that digitizing the remaining parcels from scratch would save time, money, and effort rather than continuing the rubbersheeting process. More importantly the new data would be even more accurate than rubbersheeting.
Digitize Process: (The digitizing was performed one tax map area at a time.)
A. All available paper plat drawings for the specific tax map area were acquired from the Survey Division plat archives. These plats were digitized using Coordinate Geometry (COGO). Using microstation, an X,Y coordinate was keyed into the system. Then from that beggining point the distance and directions to the next point are keyed in using the distance and bearings until the parcel outline is complete. If the subdivision or number of lots inside the parcel are small, then the lots inside the parcel are also COGO'd in using distance and bearings. If however, subdivision is complex and contains a large number of lots, the plat(s) are registered on a digitizing table and the lot lines are digitized by hand with a digitizing puck. The property lines are digitized in NAD1983, if the plats have NAD1927 coordinates, then the coordinate(s) are converted from NAD1927 to NAD1983 using a Geographic Calculator. The plat is then digitized in NAD1983. If the plat drawing had no coordinates or assumed coordinates, then the parcel(s) were digitized by starting at an arbitrary point, ie.. neighboring or existing parcel/lot line. The distance and bearings were then entered until the parcel was complete.
B. If no plat drawing is available, then the deed was examined. From the deeds the parcel had to be digitized starting from and arbitrary point (again the orthophotography or a neighboring parcel line was used as a starting point). The deeds did not usually have coordinates, they merely give distances and bearings. If a deed was not available, the property had to be drawn by tracing the lines of possession on the orthophotography.
Property Linework was seperated into stat area groupings so the work could be divided among staff. Stat area groups were chosen because they border on road right of ways only, making it easy to rejoin them at the end of the project.
The GIS division cleaned the the cadastral layer using Microstation/MGE to create topology.
The layer was converted to polygons in Microstation/MGE and exported to Mapinfo.
Once in Mapinfo, the polygons were Quality Controlled to ensure one property record per polygon. Also Road Names and Addresses were quality controlled.
The GIS Division joined the account ID data to the property polygons
The GIS Division converted the Property layer from Mapinfo to an Arc/GIS Coverage (Regions), Cleaned slivers and exported the data to a Arc/GIS Personal Geodatabase.
The Department of Planning and Zoning updates the Property Linework using Microstation on a weekly basis. The new line work is then converted an Arc Info Coverage, cleaned, and built. The resulting coverage is translated to a Personal Geodatabase and incorporated into the final Property Geodatabase. The Data is also converted back to Mapinfo
The GIS Division created a data entry tool in ArcGIS that allows DPZ to select the street address from a list that accurately reflects the official street names in the street centerline.
Land Features - Planimetrics (Street Edge, Tree Line, Buildings, Streams, etc...) (no attribution) Geodetic Control Points (attribution with scanned recovery cards) Property Boundaries (polygons with address attribution in ESRI format) Water and Sewer Utilities (no attribution) Topography (5' interval contour lines and labels) (no attribution)
No fee charged to other Federal, State, County, other local or educational entities.
Generally, users may purchase the data CDs at the Central Services desk in the basement of the George Howard Building
3450 Court House Dr Ellicott City, Maryland 21043
The customer must first sign a license agreement.
The CDs are already complete. Users will received a purchase slip, for which they must pay for the data at the purchasing office. The only Credit Card accepted is the Discover Card, but an additional fee is required.
The customer must return to the Central Services desk to pick up the CD
2.
If a potential customer cannot travel to the Howard Building, he or she may contact the Distributor to request the data.
The distributor will fax a license agreement to the potential customer, who is to complete the LA and fax it back to the distributor.
The customer will mail a check to the distributor, and make the check payable to "The Director of Finance".
Once received, the CD will then be sent via standard US mail the customer.
3.
If a potential customer is a government of educational entity, they may call the distributor and request the CD, or an individual data set from the CD.
The distributor will fax a license agreement to the potential customer, who is to complete the LA and fax it back to the distributor.
The CD or data sets requested will be mailed via standard US mail, or if the data set(s) are under 5MB, they may be emailed immediately.
2. If the potential customer contacts the distributor to request a CD, the distributor will most likely fax the license agreement to the potential customer within the business day. Once the distributor receives the completed fax, he will mail the CD immediately. Deliver time will depend on standard US mail shipping times. (Likely within one business week)
3. If the user is from a government or educational entity and requests the CD or a data set(s), the data will likely be received by the customer within one business week. If the data is emailed, it should be received within minutes depending on internet connection of the customer.
The turnaround times are not guaranteed.