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GEOLOGIC MAPPING 101:  COMMON PITFALLS AND SUGGESTIONS   FOR A MORE EFFICIENT APPROACHMark Zellman1 & Kristi Zellman21Fugr...
INTRODUCTION
COMMON TASKS                                               Polygons• Converting raster maps to vectors  • Scanned paper ma...
COMMON PROBLEMS: RASTER MAPS• Missing spatial reference control• Inaccurate spatial control• No listed spatial reference i...
MORE PROBLEMS: VECTOR CHAOS• Dangling nodes• Polygon gaps or slivers• Unclosed lines used to represent polygon features• D...
MAP EXAMPLE
MAP EXAMPLE
MAP EXAMPLE        Unit overruns                           Overshoot        fault contactGaps                             ...
UNCLOSED POLYLINES
MANAGING THE PROBLEMS• Raster Issues  • Projections:    • Research (ASPRS is a good resource)    • Comparisons with satell...
HOW TO AVOID THESE PITFALLS• Learn how to use GIS tools effectively• Don’t create GIS data in a graphics software package•...
STEP 1: HAVE A PLAN• Know your:  • Projection  • Map scale  • Map units• Establish a naming convention• Organize the attri...
STEP 1.1: SOFTWARE• You’ve got options…   1. ArcGIS Desktop + Extensions       • Digitize shapefiles and convert to polygo...
STEP 2: ORGANIZE YOUR DATA• Develop an organized file structure• Use a descriptive and progressive file naming convention
STEP 3: THE DIGITIZING WORKFLOW• Digitize the units as LINES, not polygons  • If you were to draw units, how would you do ...
STEP 4.1: LINES TO POLYGONS• ArcGIS + ET GEOWIZARDS      Shapefile        ET                                   Polygon v1 ...
STEP 4.2: LINES TO POLYGONS• ArcINFO       Shapefile                   ArcToolbox   Polygon v1       Lines v1             ...
STEP 5.1: THE EDITING PROCESS• Maintain data organization and file naming conventions• Develop an organized process for cr...
STEP 5.2: THE EDITING PROCESS                                             ArcToolbox                                      ...
STEP 6: SYMBOLOGY AND ATTRIBUTES• Use standard colors for unit polygons and standard symbols for geologic features (ESRI, ...
STEP 7: METADATA• Take time to write thorough metadata• Know what format your users are using• Use a metadata editor  • Ar...
CONCLUSION• These approaches can be applied to projects in other  disciplines• To avoid common mapping pitfalls:  • Take t...
REFERENCESFederal Geographic Data Committee [prepared for the Federal Geographic Data Committee by the U.S. GeologicalSurv...
Thank You!  Questions?
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2012 URISA Track, Geologic Mapping 101: Common Pitfalls and Suggestions for a More Efficient Approach, Mark Zellman & Kristi Zellman

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Creating maps composed of polygons and polylines within a Geographic Information System (GIS) software, such as ArcGIS, is a common task for many GIS professionals across multiple disciplines. The
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development of these types of maps can be a complex and labor intensive process. This is especially true when creating geologic maps, which represent a complex network of geologic units, faults, joints, and other features, often with cross-cutting relationships. Those who have tried to create a map like this probably realized, early in the process, that it is not as straight-forward as they imagined due to the many different work-flow patterns that exist for creating maps in a GIS. In this presentation, we will discuss common problems and how to manage them, as well as give suggestions that will make your next geologic mapping project more streamlined and organized.

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2012 URISA Track, Geologic Mapping 101: Common Pitfalls and Suggestions for a More Efficient Approach, Mark Zellman & Kristi Zellman

  1. 1. GEOLOGIC MAPPING 101: COMMON PITFALLS AND SUGGESTIONS FOR A MORE EFFICIENT APPROACHMark Zellman1 & Kristi Zellman21Fugro Consultants, Inc.2Colorado School of Mines and U.S. Geological Survey
  2. 2. INTRODUCTION
  3. 3. COMMON TASKS Polygons• Converting raster maps to vectors • Scanned paper maps • Digital raster images• Cleaning up vector messes Vector Lines• Symbolizing• Attributing• Metadata Raster Source• Publishing
  4. 4. COMMON PROBLEMS: RASTER MAPS• Missing spatial reference control• Inaccurate spatial control• No listed spatial reference information• Obscure projections• Shifted data• Mapping errors• Poor print quality• Scanning of rare and brittle historic maps• Deep creases = warped scans
  5. 5. MORE PROBLEMS: VECTOR CHAOS• Dangling nodes• Polygon gaps or slivers• Unclosed lines used to represent polygon features• Duplicate lines for single contacts (polygon to line conversion)• Poor digitizing technique• Disorganized data• Feature alignment issues
  6. 6. MAP EXAMPLE
  7. 7. MAP EXAMPLE
  8. 8. MAP EXAMPLE Unit overruns Overshoot fault contactGaps Gaps Map features extend beyond Overshoot boundary
  9. 9. UNCLOSED POLYLINES
  10. 10. MANAGING THE PROBLEMS• Raster Issues • Projections: • Research (ASPRS is a good resource) • Comparisons with satellite imagery, orthophotos, topographic maps • Trial and error • Warped Scans • Georeferencing tools: • 1st – 3rd order polynomial • Stretch• Vector Issues • Data QA/QC • Topology tools help! • Educate misguided GIS users who pass their problems to you.
  11. 11. HOW TO AVOID THESE PITFALLS• Learn how to use GIS tools effectively• Don’t create GIS data in a graphics software package• Understand your subject-matter to depict appropriately• Use a standardized method for managing vector data from the start…
  12. 12. STEP 1: HAVE A PLAN• Know your: • Projection • Map scale • Map units• Establish a naming convention• Organize the attribute table• Consider the data format (shapefile or geodatabase) • Not everybody can view your ArcGIS version 10 geodatabase files• Vector structure (faults, contacts, folds, dikes, etc..)• Plan the editing and revision process• What about software??
  13. 13. STEP 1.1: SOFTWARE• You’ve got options… 1. ArcGIS Desktop + Extensions • Digitize shapefiles and convert to polygons with extensions (ET Geowizards) 2. ArcINFO • Create as shapefiles or geodatabase files and convert to polygons • Create geodatabase files and establish topology then convert to polygons
  14. 14. STEP 2: ORGANIZE YOUR DATA• Develop an organized file structure• Use a descriptive and progressive file naming convention
  15. 15. STEP 3: THE DIGITIZING WORKFLOW• Digitize the units as LINES, not polygons • If you were to draw units, how would you do it?• Use the editing templates in ArcGIS version 10• Digitize the map boundary and faults before contacts • Keep cultural features, folds, hydrology separate – refer back to your plan.• Use snapping Points• Save often!!!! Separates Geologic Lines Geologic Polygons
  16. 16. STEP 4.1: LINES TO POLYGONS• ArcGIS + ET GEOWIZARDS Shapefile ET Polygon v1 Lines v1 Geowizards Build Polygon Tool
  17. 17. STEP 4.2: LINES TO POLYGONS• ArcINFO Shapefile ArcToolbox Polygon v1 Lines v1 Feature to Polygon Geodatabase Editor GDB Lines v1 Toolbar Polygon v1 Construct Topology Rules Polygons
  18. 18. STEP 5.1: THE EDITING PROCESS• Maintain data organization and file naming conventions• Develop an organized process for creating, editing and updating files• Edited polygons require updated attributes (preserve attributes)
  19. 19. STEP 5.2: THE EDITING PROCESS ArcToolbox Points v1 Feature to Point • Preserve Attributes • Choose Inside Option Editor Toolbar Polygon v2Option 1 Polygon v1 Topology Edits ArcToolboxOption 2 Lines v1 Line v2 Polygon v2 Line to Feature • Import attributes Edits from Points v1
  20. 20. STEP 6: SYMBOLOGY AND ATTRIBUTES• Use standard colors for unit polygons and standard symbols for geologic features (ESRI, USGS) • FGDC Digital Cartographic Standard for Geologic Map Symbolization (FGDC, 2006) • ESRI Geologic Map Template • ESRI symbol template pallet• Important traits for attributes • Consistency • Limitation • Descriptive • Easy for a user to interpret
  21. 21. STEP 7: METADATA• Take time to write thorough metadata• Know what format your users are using• Use a metadata editor • ArcCatalog • EPA Metadata Editor
  22. 22. CONCLUSION• These approaches can be applied to projects in other disciplines• To avoid common mapping pitfalls: • Take the time to make a plan before you start a GIS project • Understand your subject matter and audience • Always take the time to write thorough metadata • A standard and organized approach is necessary
  23. 23. REFERENCESFederal Geographic Data Committee [prepared for the Federal Geographic Data Committee by the U.S. GeologicalSurvey], 2006, FGDC Digital Cartographic Standard for Geologic Map Symbolization: Reston, Va., Federal Geographic DataCommittee Document Number FGDC-STD-013-2006, 290 p., 2 plates.EPA Metadata Editor (EME), version 3.1.2, 2012; https://edg.epa.gov/EME/Home.htm
  24. 24. Thank You! Questions?

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