1. L7 –Maps & Data Entry Chapter 4 – pp 153-End Lecture 71

2. When do we need a transformation ? Digitizing from legacy maps Digitizing from suitable aerial photos Lecture 72

3. Coordinate Transformation Also called registration, as it registers the map layers to a map coordinate system. Requires a set of control points. –Must be as accurate as the desired outcome. –Evenly distributed over the area. –Sufficient number. Commonly used to convert newly digitized data to a standard coordinate system. Lecture 73

4. Control Points How many are enough? – 12 to 30 recommended How should they be distributed? – at least 3 in each quadrant Best to have an independent, higher order set – the control data should be at least as accurate (hopefully 10 times more accurate) than the data to be transformed. Lecture 74

5. Equiarea Transformation Equiarea (congruence) Transformation: –The method allows rotation of the rectangle and preserves its shape and size. Lecture 75

6. Similarity Transformation Similarity Transformation: –The method allows rotation of the rectangle and preserves its shape but not size. Lecture 76

7. Projective Transformation Projective Transformation: –The method allows angular and length distortion, thus allowing the rectangle to be transformed into an irregular quadrilateral. Lecture 77

8. Topological Transformation Topological Transformation: –The method preserves the topological properties of an object but not shape, thus allowing the rectangle to be transformed into a circle. –Also called rubber sheeting Lecture 78

9. Affine Transformation Affine Transformation: –The method allows angular distortion but preserves the parallelism of lines. –While preserving line parallelism, the affine transformation allows rotation, translation, skew, and differential scaling on the rectangular object. Lecture 79

10. Developing the Transformation Equations Coordinates in the source system Coordinates in the target system Estimate equations that allow us to calculate the target coordinates given any set of source coordinates Lecture 710

11. Affine Transformation Target coordinates a first-order linear function of source coordinates Known as an Affine Transformation: Easting = T e + a 1 x + a 2 y Northing = T n + b 1 x + b 2 y T shifts origin b i & a i changes scale & rotation Lecture 711

12. Example Road intersection: –Real world coordinates: E=500,000 & N=4,800,000 –Digitized coordinates: x=125 & y= 100 Each control point provides two equations. Lecture 712

13. Lecture 713

14. RMSE = e 2 1 + e 2 2 + e 2 3 … n Lecture 714

15. Lecture 715

16. Lecture 716

17. Higher order polynomial transformation Named for the largest exponent in the transformation equation. ArcMap supports first to third order transformation. Command line supports first to twelfth order transformation. Use the lowest order transformation that provides acceptable results Lecture 717

18. Lecture 718

19. Raster Geometry and Resampling Data must often be resampled when converting between coordinate systems or changing the cell size of a raster data set. Common methods: –Nearest neighbor –Bilinear interpolation –Cubic convolution Lecture 719

20. Lecture 720

21. What if the cells aren’t “well behaved” Lecture 721

22. Orientation and/or Cell Size May Differ Lecture 722

23. Resampling - Distance-weighted averaging bilinear interpolation Lecture 723

24. Map Transformation - Summary From 2-d to 2-d system Requires mutually identified control points Linear (affine) transformation is best Sufficient, well-distributed control points Should not be used in place of a map projection! Lecture 724

25. Types of GIS Output Maps: Everyone recognizes this most common output from a GIS. Cartograms: These special maps that distort geographic features based on their output values rather than their size. Charts: GIS can produce pie charts, histograms (bar charts), line charts, and even pictures in addition to maps. Lecture 725

26. Types of GIS Output Directions: Another common output, directions show you how to get from one place to another. Customer lists: Business GIS applications often produce customer lists, sometimes with printed mailing labels. 3D diagrams and movies: These forms of GIS output help you see the results of your work realistically and dramatically. Lecture 726

27. Maps as Output The map is still the most common form of output. Map design elements to be considered: –Frame of reference –Projection –Features to be mapped –Level of generalization –Annotations –Symbolism Maps should show only as much detail as necessary to get the point across. Lecture 727

28. Cartographic Design Most design choices are compromises Design is a process –Stage 1 – type of map, data to be represented, size, shape, basic layout. Data type is the most important factor in determining map type and symbols –Stage 2 – kinds of symbolism, number of classes, class limits, color, line weights. –Stage 3 – define all symbols, typography (font, size, positions etc.) Lecture 728

29. Making Great Maps Lecture 729

30. https://www.youtube.com/results?search_query= ArcGIS+making+great+maps Making Better Map Layouts with ArcGIS (1 hour) Lecture 730

31. Qualitative Data Make symbols as intuitive as possible Use professional standards whenever possible Legends Lecture 731

32. Contrast – bad example Lecture 732

33. Contrast – good example Lecture 733

34. Typography & Lettering Use concise formulated captions Avoid using more than four fonts Establish a typographic hierarchy Develop legibility Black lettering on yellow ---- most legible Red lettering on green ---- least legible Lecture 734

35. Example: hello world Hard to read better Lecture 735

36. Text Placement Placing text on a map is one of the most time consuming tasks, as much as 50% of the final map production time. Poor placement of text affects the readability of the map, this is especially true in regions where map symbols are densely clustered. Situations often arise in which text must overwrite other symbols with which it has no logical association. Lecture 736

37. Automated Name Placement Components of name placement systems: –Specification of map features and text characteristics. –Generation of trial name positions. –Selection of optimal labels. –Scale at which labels will be displayed Font type, color and size must also be specified. It is desirable to name as many features as possible, while recognizing that some features will remain unlabeled. Named features should be ranked in some way to resolve conflicts. Lecture 737

38. Non-Traditional Maps Cartogram Multimedia output Hybrid – Map overlaying an image 3D Virtual GIS Lecture 738

39. Cartogram Lecture 739

40. Cartogram http://www-personal.umich.edu/~mejn/election/2008/ 2008 Election Results by State Results on A Population Cartogram Lecture 740

41. http://amphibiaweb.org/amphibian/cartogra ms/ Lecture 741

42. Figure 8.9 Example of multimedia content in GIS displays Source: Screenshot shows ESRI Graphical User Interface (GUI). ArcMap, ArcView and ArcInfo Graphical User Interfaces are the intellectual property of ESRI and is used herein with permission. Copyright © 2005 ESRI all rights reserved Lecture 742

43. Maps and Images Lecture 743

44. 3D Maps http://www.vidiani.com/?p=10431 Lecture 744

45. THE OUTPUT FROM GIS ANALYSIS TABLES AND CHARTS Used with maps or alone to improve understanding of cartographic results Whenever map output is less immediately understood by audience –Tables and charts are generally more understood by general public than maps are Map is not appropriate for the output Show summaries of attribute data and relationships among them –Explicitly spatial –Implicitly spatial Lecture 745

46. THE OUTPUT FROM GIS ANALYSIS TABLE AND CHART DESIGN Should be readily understood with minimal explanations Appropriate titles for each table and chart presented Label axes on all graphs Provide legends wherever appropriate Use fonts types and sizes that are easily read – Arial Chose colors wisely as not to mislead audience –E.g. human eye is drawn to reds much more readily than to whites Using red lines against white ones will draw the eye towards one and away from the other – is that what you wish? Avoid plotting more than 3 distinct attributes per plot Lecture 746

47. Good for comparing values and showing trends Bar Chart Lecture 747

48. Good for comparing values and showing trends Column Chart Lecture 748

49. Good for showing the relative value for each category as well as the total. Area Chart Lecture 749

50. Combines features of both the bar and area charts Cumulative Bar Chart Lecture 750

51. Shows relationships between the parts and the whole, particularly useful for showing proportions and ratios. Pie Charts Lecture 751

52. Emphasizes rate of change. Particularly good for representing trends over a period of time. Line Charts Lecture 752

53. Reveals trends or patterns in the data. Can help reveal associations, sometimes cause-and-effect relationships. Scatter Charts Lecture 753

54. The Geodatabase Lecture 754

55. What is the geodatabase? An ArcGIS geodatabase is a collection of geographic datasets of various types held in a common file system folder: – a Microsoft Access database, –A multiuser relational database (such as Oracle, Microsoft SQL Server, PostgreSQL, Informix, or IBM DB2). Lecture 755

56. Fundamental datasets in the geodatabase A key geodatabase concept is the dataset. It is the primary mechanism used to organize and use geographic information in ArcGIS. The geodatabase contains three primary dataset types: –Feature classes –Raster datasets –Tables Lecture 756

57. Lecture 757 A feature class is stored as a table. Each row represents one feature. In the polygon feature class table below, the Shape column holds the polygon geometry for each feature. The value Polygon is used to specify that the field contains the coordinates and geometry that defines one polygon in each row.

58. Data in a Geodatabase Lecture 758

59. Feature Class Conceptual representation of a category of geographic features. Includes point, line, poly & annotation When shapefiles are added to a GDB their computer representation is changed This is why you cannot drag and drop a shapefile into a GDB. You have to load it or Import it. Lecture 759

60. Feature Dataset A collection of feature classes that share the same spatial reference. It is because they share the same spatial reference that they can participate in topological relationships with each other. Several feature classes with the same geometry may be stored in the same feature dataset. Object geometry and relationship classes can also be stored in a feature dataset Lecture 760

61. Lecture 761 Geodatabase Feature Dataset Feature Classes Stand alone Feature Classes

62. Lecture 762 } Cover Line(arc) point poly Anno Table

63. Lecture 763 Catalog View WE view

64. Lecture 764 Catalog View WE view

65. Advantages Can be moved as a unit, regardless of how much stuff is in it. Faster Can get at it through Microsoft Access, if you know what you are doing, Stores topology Lecture 765

66. Advantages TOPOLOGY? = the arrangement that defines how point, line, and polygon features share coincident geometry. Examples: – Fire hydrants must fall on water mains, – Adjacent soil polygons must share their common boundaries. Lecture 766

67. Topology Many datasets have features that could share boundaries or corners By creating a Topology you set up rules defining how features share their geometries. Editing a boundary or vertex shared by two or more features updates the shape of all of them. Lecture 767

68. Topology Rules Govern the relationships between between features within a FC or features in different FCs Example: moving a slope boundary in in one FC could update two slope class polys AND update a forest stand boundary in another FC. Topology editing tools in ArcMap are used to create and change the rules Lecture 768

69. Geometric Networks Some vector datasets need to support connectivity tracing and network connectivity rules –Communications –Pipelines –Transportation (roads, railroads, canals) Geometric networks allow you to turn simple point and line features into network edge and junction features Lecture 769

70. Creating a Geodatabase In ArcCatalog! Point to where you want to put the new GDB Click New>Personal GDB Type in a new name Lecture 770

71. Adding Data Lecture 771 In Catalog… Right click and select New You get

72. Copying Data You can copy/paste data between GDBs OR You can import shapefiles, coverages, computer-aided drafting (CAD) data, and GeoDatabase FCs into a GDB Lecture 772

73. Importing Shapefiles Lecture 773 feature class that's in another coordinate system. –You MUST project to the spatial definition of the GDB –Then right click on GDB and select Import --------- 

74. Planning for Your Geodatabase What is the problem? What data is needed (scale, extent, etc.0? What kinds of relationships are needed between FC? How will the data be organized (FDS)? Lecture 774

75. Summary The Geodatabase is a container for all types of geographic data. A feature dataset contains features that share a projection and geographic space. Lecture 775