| Category |
Land Data Base lb_data |
| Name(s) |
.bridges .dams .hydro .plss .rails .streets |
| Description |
Select Planimetric Features |
| Type |
ArcInfo Library base_lib |
| |
|
| Abstract |
The planimetric feature sets represent a collection of linear features that we usually see on reference maps and are extremely important to all GIS/mapping applications. Available planimetric feature data layers include Bridges, Dams, Streams/Shorelines, select Public Land Survey System Section Corners, Railroads, and Edge-of- Pavement features initially collected from April 1993 aerial photography. |
| |
|
| Maintenance |
Selective updates to the original planimetric feature sets were made for areas where significant change occurred based upon April 1997 aerial photography. Maintenance of planimetric features data layers continues using the "Planimetric Feature Maintenance Application" developed in Arc Macro Language (AML) by ITSD. Year 2000 modifications corrected the feature creation/modification date field. Future plans include exploring the integration of field data collected by Engineering for maintenance and enhance the planimetric data layers. |
| |
|
| Source |
Large-Scale GIS Data Base Development Project (1993) and Update Project (1997) |
| |
|
Agency/
Contact |
Information Technology Services Department / mjohnson@ci.ann-arbor.mi.us |
| |
|
| Accuracy |
National Map Accuracy Standards for 1"=100', 1:1200, 1-2 foot positional accuracy |
| Projection |
NAD83 State Plane, Michigan South Zone 6401 |
| Units |
US Survey Feet |
| Spheroid |
GRS1980 |
| |
|
| Domain |
Large-Scale GIS Data Base Update Project Area, 51.5 Square Miles |
| Format |
Double Precision Coverages with INFO attributes |
| Tiles |
96 tiles measuring 4,000' by 6,000', ctiles |
| Count |
See Qualifications Table |
| |
|
| Enumeration |
| Layer |
Layer |
Coverage |
Num |
Num |
Num |
Num |
| Name |
Description |
Name |
Arcs |
Polygons |
Points |
Anno Subclass |
| .bridges |
Bridges/
Overpasses |
brdg_cov |
143 |
134 |
- |
- |
| .dams |
Water Impoundment Structures |
dams_cov |
27 |
9 |
- |
- |
| .hydro |
Streams/
Shorelines |
hydr_cov |
3337 |
822 |
- |
name/70 |
| .plss |
Section
Corners |
plss_cov |
- |
- |
56 |
- |
| .rails |
Railroads |
rail_cov |
99 |
- |
- |
name/64 |
| .streets |
Edge-of-
Pavement |
pave_cov |
5207 |
- |
- |
- |
|
| |
|
| Qualifications |
The April 1993 black and white aerial photography used for the production of the planimetric feature sets has a photo scale of 1:15,840 or 1"=1,320' with 60% forward lap and 30% side lap on Agfa Pan 50 film. Control panels on the ground were used in the aerial mission flown at an altitude of 7,920 feet.
The April 1997 black and white aerial photography used for the production of the planimetric feature sets has a photo scale of 1:7,680 or 1"=640' with 55-65% forward lap and side lap on Kodak 2405 film. Airborne GPS technology along with control panels on the ground were used in the aerial mission flown at an altitude of 3,840 feet. Selective update minimized for funding necessary for the update of planimetric feature sets by focusing resources on areas of significant change between April 1993 and April 1997.
The 9"x9" contact prints of 1993 and 1997 aerial photography are on file at the Planning Department. |
