1. GIS Tutorial 1
Lecture 6
Digitizing

2. Outline Digitizing overview GIS features Digitizing features
Advanced digitizing tools
Spatial adjustments
Digitizing sources
GIS TUTORIAL 1 - Basic Workbook

3. Lecture 6
Digitizing overview
GIS TUTORIAL 1 - Basic Workbook

4. Why digitize? New maps Map features are wrong Missing features Other?
GIS TUTORIAL 1 - Basic Workbook

5. Heads down digitizing Digitizing tablets
Used to digitize hard copy maps into GIS
Transform wire intersections into coordinates of the tablet’s coordinate system
GIS TUTORIAL 1 - Basic Workbook

6. Steps for heads down digitizing
Tape map to the digitizer
Register control points on the map
Estimate two conversion equations (one for vertical and one for horizontal coordinates)
Digitize vectors (points, lines, or polygons)
Tape
Control
points
Puck
Map
GIS TUTORIAL 1 - Basic Workbook 6

7. Heads up digitizing Mouse on a screen
Digitizes paper maps, aerial photos, or other images
GIS TUTORIAL 1 - Basic Workbook 7

8. Lecture 6
Gis features
GIS TUTORIAL 1 - Basic Workbook

9. Points Single features Nodes Vertex points Line endpoints
Controls shapes of lines and polygons
GIS TUTORIAL 1 - Basic Workbook

10. Creating points Heads up digitizing Points added as XY event files
Single point features
Sketch tool and snapping features
Points added as XY event files
Points geocoded using addresses
GIS TUTORIAL 1 - Basic Workbook

11. Lines Starting and ending points with shape vertices as needed
Vertex points
GIS TUTORIAL 1 - Basic Workbook

12. Lines Physical attributes of TIGER streets Shape
From and To attributes
Node
Address
Lat/long
Length
GIS TUTORIAL 1 - Basic Workbook

13. Polygons Three or more lines joined to form a closed area
Single polygons or multipart features
(Hawaiian islands can be multiple polygons as one feature) 1 2 4 3
GIS TUTORIAL 1 - Basic Workbook

14. Polygons Physical attributes Shape Area Perimeter Length
GIS TUTORIAL 1 - Basic Workbook

15. Lecture 6
Digitizing features
GIS TUTORIAL 1 - Basic Workbook

16. Create new feature class
Created in ArcCatalog
GIS TUTORIAL 1 - Basic Workbook

17. Create new feature class
Add spatial reference information
GIS TUTORIAL 1 - Basic Workbook

18. Create new feature class
Add new fields
GIS TUTORIAL 1 - Basic Workbook

19. Create new feature class
Feature class created
GIS TUTORIAL 1 - Basic Workbook

20. Creating Feature Layers or Shapefiles in ArcMap
Within ArcMap:
Locate an existing data layer that is similar to the layer that you wish to create.
Start editing the existing layer, then digitize the new feature
Select the new feature
Export the selection to a shapefile
Add the shapefile- fields already present and map projection
is already defined
Examples in the instructor exercise
GIS TUTORIAL 1 - Basic Workbook

21. Digitize new features Create base map Add feature in ArcMap
Start editing (Editor toolbar)
Digitize feature
Stop editing and save
GIS TUTORIAL 1 - Basic Workbook

22. Create base map for digitizing
Vector features or raster images
GIS TUTORIAL 1 - Basic Workbook

23. Add new feature class
GIS TUTORIAL 1 - Basic Workbook

24. Add Editor toolbar Customize, Toolbars, Editor toolbar
GIS TUTORIAL 1 - Basic Workbook

25. Start editing
Editor, Start editing
GIS TUTORIAL 1 - Basic Workbook

26. Begin digitizing
GIS TUTORIAL 1 - Basic Workbook

27. Click point (tree) locations
GIS TUTORIAL 1 - Basic Workbook

28. Stop editing
Editor, Stop editing
GIS TUTORIAL 1 - Basic Workbook

29. Edit attribute data Start editing, populate fields in table 1 2
GIS TUTORIAL 1 - Basic Workbook

30. Advanced Digitizing tools
Lecture 6
Advanced Digitizing tools
GIS TUTORIAL 1 - Basic Workbook

31. Specify angle and length
Lines and polygons
Straight segment tool
Type length and angle
GIS TUTORIAL 1 - Basic Workbook

32. Snapping tools Snapping toolbar GIS TUTORIAL 1 - Basic Workbook
Point Snapping
Snapping toolbar
Endpoint Snapping
Vertex Snapping
Edge Snapping
GIS TUTORIAL 1 - Basic Workbook

33. Trace tool Good for complicated shapes Editor toolbar, Trace tool
GIS TUTORIAL 1 - Basic Workbook

34. Generalize tool
Creates features for use at small scales with less detail while preserving basic shapes
U.S. Census cartographic boundary files
Census TIGER water feature
City planning rivers
GIS TUTORIAL 1 - Basic Workbook

35. Smooth tool
Smoothes sharp angles in polygon outlines to improve aesthetic or cartographic quality
Smooth before
Smooth after
GIS TUTORIAL 1 - Basic Workbook

36. Cut polygons Creates two polygons from one original Cut polygon tool
Polygon before
Polygon after
GIS TUTORIAL 1 - Basic Workbook

37. Lecture 6
Spatial adjustments
GIS TUTORIAL 1 - Basic Workbook

38. Transforms Converts data Shifts data
from one coordinate system to another.
from digitizer or scanner units to real world coordinates.
Shifts data
within a coordinate system, (e.g. feet to meters).
GIS TUTORIAL 1 - Basic Workbook

39. Rubbersheeting Geometric distortions commonly occur in source maps
may be introduced by imperfect registration in map compilation
lack of geodetic control in source data
variety of other causes
Corrects flaws through the geometric adjustment of coordinates
GIS TUTORIAL 1 - Basic Workbook

40. Edgematching
Aligns features along the edge of one layer to features of an adjoining layer
Layer with the less accurate features is adjusted, while the adjoining layer is used as the control.
Attribute transfer is typically used to copy attributes from a less accurate layer to a more accurate one.
GIS TUTORIAL 1 - Basic Workbook

41. Spatial adjustment example
Hamburg Hall CAD Drawing
CAD drawings generally do not have geographic coordinates
GIS TUTORIAL 1 - Basic Workbook

42. Spatial adjustment example
Spatially match drawing to map using displacement links
GIS TUTORIAL 1 - Basic Workbook

43. Lecture 6
Digitizing sources
GIS TUTORIAL 1 - Basic Workbook

44. USGS United States Geological Survey Common Data Types & Standards
Digital Elevation Models (DEMs)
Digital Orthophoto Quads(DOQQs)
Digital Line Graphs(DLGs)
Digital Raster Graphics (DRGs)
Landsat Satellite Images
Land Use Land Cover (LULC)
Spatial Data Transfer Standard(SDTS)
GIS TUTORIAL 1 - Basic Workbook

45. Orthophotography
Digital imagery in which distortion from the camera angle and topography have been removed, thus equalizing the distances represented on the image
This is a clipped portion of the SE quadrant of Lombard, IL. Projection: UTM (16N), NAD83
Source date: 17-APR-98
GIS TUTORIAL 1 - Basic Workbook

46. Digital Ortho Quarter Quads—DOQQs
Grayscale or color-infrared (CIR) images
1-meter ground resolution;
Cover an area measuring 3.75 minutes longitude by 3.75 minutes latitude, approximately 5 miles on each side
Referenced to the North American Datum of 1983 (NAD83) and cast on the Universal Transverse Mercator (UTM) projection
DOQQ _ Digital Ortho Quarter Quad
a computer-generated image of an aerial photograph in which image displacement caused by terrain relief and camera tilts has been removed. It combines the image characteristics of a photograph with the geometric qualities of a map. 
GIS TUTORIAL 1 - Basic Workbook

47. DOQQ image resolutions
The ground length of one pixel of the image
image with one meter resolution means that each pixel in the image represents one square meter on the ground.
30 meters
10 meters
5 meters
GIS TUTORIAL 1 - Basic Workbook

48. DOQQ image resolutions
2 meters
1 meter
GIS TUTORIAL 1 - Basic Workbook

49. National Elevation Data Sets
United States Geological Survey (USGS) National Elevation Dataset (NED) Shaded Relief Imagery Data (Free)
Maps provide highest-resolution elevation data available across the United States, in raster format
GIS TUTORIAL 1 - Basic Workbook

50. Scanning paper documents
Raster to vector conversion
Paper (historic) maps
Scanned maps and images become vectors
Special software needed
GIS TUTORIAL 1 - Basic Workbook

51. Summary Digitizing overview GIS features Digitizing features
Advanced digitizing tools
Spatial adjustments
Digitizing sources
GIS TUTORIAL 1 - Basic Workbook