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Graphic Data Clean-Up Issues

Graphic Data Clean-Up Issues. Graphic Data Clean-up. Very Important if you plan to use existing CAD or GIS data from another agency, department, or private vendor as a base map. Error Correction before you begin is key. Spatial errors (ie projection/coordinate systems)

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Graphic Data Clean-Up Issues

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  1. Graphic Data Clean-Up Issues

  2. Graphic Data Clean-up • Very Important if you plan to use existing CAD or GIS data from another agency, department, or private vendor as a base map. • Error Correction before you begin is key. • Spatial errors (ie projection/coordinate systems) • Topological (duplicate lines, gaps, dangles, etc.)

  3. Graphic Data Clean-up (cont.) • Existing Attribute linkages on the graphics can also cause “headaches”. • Particularly if you plan to use graphics that were attached to databases. • Those “old” linkages can cling to the graphic elements and cause troubles later. • Potential errors are dependent upon which GIS or 911 software is being implemented.

  4. Line Weeding • Line Weeding reduces the size and complexity of linear data based on a user defined tolerance • Line Weeding performs distance checks on linear data • Benefits of weeding linework: • Significant improvement in screen update times, plot-stroking performance, and spatial analysis processing time • Reduced disk space requirements

  5. Cleaning CAD Linework • The line cleaning tools correct errors in 2-D and 3-D linework. • The line cleaning tools can: • correct undershoots or overshoots • break intersections • remove short segments • merge duplicate line segments • The line cleaning tools can process: • lines, line strings, arcs, curves, shapes, ellipses, complex strings, and complex shapes

  6. Common Line work checks • Intersection Processing -- either break or flag intersections. • Duplicate Line Processing -- merges duplicate line work in 2-D and 3-D design files. • Short Segment Processing -- removes zero-length lines and short segments that have at least one free endpoint in 2-D and 3-D line work. • Endpoint Processing -- corrects or flags free endpoints, the free endpoints can be either overshoots or undershoots.

  7. Graphic Attributes also need to be checked • TIGER Address Ranges, for example, are often incorrect (or blank) in Rural areas. • Can be corrected and updated, but its tedious work! • Allow me to demonstrate, using a very simple set of data and GIS software package.

  8. Attribute Edits • Selected a street segment with a “NULL” value for the address column.

  9. Attribute Edits • Edit the Attribute Table to reflect the address ranges on the left and right side of the street. • Geocode a sample address.

  10. Attribute Edits • Confirm that the street segment is properly oriented for placing the “odd” address on the correct side of the street. 105 Gadberry Dr.

  11. Attribute Edits • Re-edit the Attribute table. • Reverse the increase in value in the left and right address columns.

  12. Attribute Edits • Geocode the same address as before. • Resulting geocode location will be the opposite end of street segment.

  13. Attribute Edits • This is overly simplified for the purpose of this demonstration, but this is basically how you could go about updating the TIGER data for a county.

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