2. GIS Modeling Week 2 — Maps as Data GEOG 3110 –University of Denver Points, lines, polygons and surfaces; Discrete vs. Continuous data; Map data types and their implications; Displaying grid data; Contouring implications; Grid map structure and storage Presented by Joseph K. Berry W. M. Keck Scholar, Department of Geography, University of Denver

3. Who We Are (Class Photo) Student Statements Student Statements posted at… posted at… Class Website Class Website Email_dial og Email_dial og ClassMakeup Grading Policy and Logistics Grading Policy and Logistics

4. What GIS Is (and isn’t) Computer Mapping (70’s) - Spatial dB Management (80’s) - GIS Modeling (90’s) Now, Where Were We? GIS Modeling (Berry) …keeping in mind that the current frontier is primarily focused on Multimedia Mapping (00’s) …that radically changes our Map Paradigm Spatial Statistics — Spatial Statistics — “numerical” relationships within and among mapped data (Surface Modeling and Spatial Data Mining) From mapping to Spatial Reasoning… Spatial Analysis — Spatial Analysis — “contextual” relationships “contextual” relationships within and among mapped data (Reclassify, Overlay, Distance, Neighbors) …but we didn’t finish last week’s material!!!

5. Campground Suitability Model Review (Logic) Prefer Gentle Slopes, Near Roads, Near Water, View of Water and Westerly Oriented …but can’t be too close to water or too steep (Berry) 1 1) Base maps 5 5) Constraint maps 6 6) Final map Worst Red Best Green Constrained Black 2 2) Derived maps Algorithm 3 3) Interpreted maps Calibrate 4 4) Combined / Modeled maps Weight

6. Campground Suitability Model Review (Solution) A sequencing of map analysis commands are applied to implement model logic— using a command script (Tutor25_Campground.scr) (Berry) Solution set of maps are created by evaluating the model logic for the unique pattern of conditions at each geographic location …grid cell Worst Red Best Green Constrained Black

7. Spatial Data vs. Spatial Information From GIS as a Toolbox enabling display and geo- query to a Sandbox for developing, communicating, interacting and evaluating solutions to complex spatial problems— …from Where is What to So What, Why and What If (Berry) (digital slide show BB-BK) BB-BK Tropical Resources Institute Yale University — 1988 Yale University — 1988 Compaq II Portable Computer Summagraphics Bit Pad Digitizer Infusing Stakeholder Perspectives Spatial Reasoning and Dialogue Consultant Heaven Consultant Hell

8. Manual cartography utilizes points, lines and areas as the basic building blocks for characterizing geographic space Basic Map Features (Berry) …traditionally all maps are composed of three fundamental map features—Points, Lines and Areas. The digital map provides additional dimensions of depth and time to extend the features to Surfaces, Volumes, hyper-Volumes and fuzzy-Features Based on spatial objects (discrete) New map feature type based on grid cells (continuous) Grid-based mapped data

9. Storing Points, Lines and Areas (Berry) …how do you think Vector and Raster data structures store Surfaces, Volumes, hyper-Volumes and fuzzy-Features?

10. …replaced by the concept of Resolution (Spatial, Mapping, Thematic and Temporal) Spatial Resolution …does not exist in a GIS (Berry) …heresy!!! The concept of Scale S= MD / GD (Map Distance / Ground Distance)

11. Minimum Mapping Resolution (Berry) …replaced by the concept of Resolution (Spatial, Mapping, Thematic and Temporal)

12. Thematic and Temporal Resolutions (Berry) …so what is the difference between the concepts of PRECISION and ACCURACY …and how do these concepts relate to the concept of RESOLUTION ? …replaced by the concept of Resolution (Spatial, Mapping, Thematic and Temporal)

13. Handheld GPS unit Precision GPS unit Accuracy vs. Precision …the “target analogy” compares measurements to the pattern of arrows shot at a target Accuracy versus Precision (Berry) The Wikipedia defines Accuracy as “the degree of veracity” (exactness) while Precision as “the degree of reproducibility” (repeatable) High Accuracy but Low Precision High Precision but Low Accuracy Accuracy describes the closeness of arrows to the bull’s-eye at the target center (actual/correct) Precision relates to the size of the cluster of arrows— grouped tightly together is considered precise

14. Photo Interpreter A Cottonwood Photo Interpreter C Cottonwood Photo Interpreter B Ponderosa Pine Accuracy = classification (What) Vegetation Parcel Mapping Superimposed interpretation boundaries Precision = delineation (Where) Interpreter A Interpreter B Interpreter C Classification versus Delineation (spatial perspective) Classification Accuracy (What)  Delineation Precision (Where) (Berry) …so what is the interpretation of PRECISION and ACCURACY for Remote Sensing Classification maps?

15. Homeowners EnvironmentalistsEngineers HD & VE times 10 RP & SA times 10 HD & RP times 10 Start End EngineersEnvironmentalistsHomeowners IndividualSolutions Model Accuracy/Precision (spatial modeling perspective) CalibrateExpertOpinion …cognitive mapping has no definitive right/wrongsolution—MostPreferred WeightStakeholderValues CombinedSolution Start End Average of the three cost surfaces Optimal Path OptimalCorridor (Berry) MostPreferredLeastPreferred Routing Criteria 1 2 3 4 5 6 7 8 9 Housing Density Road Proximity Sensitive Areas Visual Exposure

16. GIS Maps contain— Points, lines, polygons Grid surfaces Raster images Pseudo grids It is important to note that the map features in a vector-based mapping system identify discrete, irregular spatial objects with sharp abrupt boundaries. Raster data types — grid surfaces, raster images and pseudo grids — treat space in entirely different manner to portray spatially continuous data Raster Data Types (Berry) …mapped data ready for map analysis and modeling Map Layer …in a raster image (aka photo) the values stored at each map location identify its color (hue, saturation and brightness)– constrained integer value (0-255) …in a pseudo grid each grid element is treated as a separate polygon (square) with spatial and attribute tables defining the set of little polygons; primarily use for “walking” information between Grid and Vector systems

17. Grid Map A Grid Map consists of a matrix of numbers with a value indicating the characteristic /condition at each grid cell location Map Stack …forming a geo-registered set of Map Layers …forming a geo-registered set of Map Layers or “Map Stack” Basic Grid Data Structure LinesFill Layer Mesh The Analysis Frame provides consistent “parceling” needed for map analysis and extends discrete Point, Line and Areal features to continuous Map Surfaces Data listing for a Map Stack Drill-down Col 3, Row 22 Analysis Frame Layer Mesh

18. Basic Grid Display Types Display Types … Lattice display forms a smooth wireframe Grid display forms chunky extruded grids (See Example Applications, “Display Types” for more information) Example ApplicationsExample Applications (Berry) …so how is a Contour Map generated? (vector representation of a surface) Contour line 1900

19. Thematic Display (Shading Manager) (See Example Applications, “Display Types” for more information) Example ApplicationsExample Applications MapCalc Shading Manager… # Ranges sets the number of intervals Equal Ranges has the same range for each interval Equal Ranges has the same range for each interval (or Equal Count has the same number of cells for each interval) (Berry)

20. Contouring Mapped Data (Display Mode) Display the elevation surface as wireframe (Lattice) with filled floor contours Display the elevation surface as wireframe (Lattice) with filled floor contours Set #Ranges to 7 and assign yellow as the inflection color Set #Ranges to 7 and assign yellow as the inflection color Redisplay the surface as Redisplay the surface as Equal Count, Equal Ranges, StDev and User Defined (Natural Breaks?) (Berry) +/- 1Stdev Equal Count Equal Ranges …note the dramatic differences in the shape and position of the boundary lines of the discrete contour intervals User Defined (300 Step) So which discrete map of the elevation surface is CORRECT ? …are the differences in Precision or Accuracy?

21. Matching Data Types & Display Types/Forms (See Example Applications, “Data Types”, “Color Interval/Pallet”, “3D Display Options” and “Data Inspection and Charting” for related information) Example ApplicationsExample Applications (Berry) 3D Toggle changes 2D and 3D display forms Display Form… Use Cells toggles between Lattice and Grid display types Display Type… Data Type toggles between Discrete and Continuous data types Data Type…

22. Numeric and Geographic Data Types …all digital maps are composed of organized sets of numbers— the Data Type determines what “map-ematical” processing can be done with the numbers on a map, or stack of map layers (Berry)

23. Homework Exercise #2 (Berry) Part 1 – Understanding Basic Concepts and Terms Scale and Resolution. 1 ) Map Scale, 2) Spatial Resolution, 3) Thematic Resolution, 4) Minimum Mapping Resolution and 5) Temporal Resolution. Scale and Resolution. 1 ) Map Scale, 2) Spatial Resolution, 3) Thematic Resolution, 4) Minimum Mapping Resolution and 5) Temporal Resolution. Data Types. 1) Nominal, 2) Ordinal, 3) Interval, 4) Ratio, 5) Binary, 6) Choropleth, 7) Isopleth data types (be sure to distinguish which data types are Numeric and which are Geographic) Data Types. 1) Nominal, 2) Ordinal, 3) Interval, 4) Ratio, 5) Binary, 6) Choropleth, 7) Isopleth data types (be sure to distinguish which data types are Numeric and which are Geographic) Display Considerations. You will generate different map displays of the Slope and Districts map layers, then identify/comment on the Data Type, Display Type and Display Form used and discuss the effects/appearance of the different displays Display Considerations. You will generate different map displays of the Slope and Districts map layers, then identify/comment on the Data Type, Display Type and Display Form used and discuss the effects/appearance of the different displays Part 2 – Characterizing Geographic Space …Discrete versus Continuous Thematic Mapping. You will use the Shading Manager to create different map displays while investigating the effects of Calculation Mode (Equal Ranges, Equal Count,+/- 1 Standard Deviation and User Defined), Number of Ranges and Color Ramp assignments. Thematic Mapping. You will use the Shading Manager to create different map displays while investigating the effects of Calculation Mode (Equal Ranges, Equal Count,+/- 1 Standard Deviation and User Defined), Number of Ranges and Color Ramp assignments.

24. Simple Erosion Model (Berry) (Exercise #2, Part 3) Create a slope map Create a slope map Reclassify that map for slope classes Reclassify that map for slope classes Create a flow map Create a flow map Reclassify that map for flow classes Reclassify that map for flow classes Combine the maps of slope classes and flow classes Combine the maps of slope classes and flow classes …result is a map with a 2- digit code …result is a map with a 2- digit code 1 St digit = flow class 2 nd digit = slope class

25. So Where Are You in GIS? (Berry) “…of the Computer ” “…of the Application” …changing our Map Paradigm Computer Programmer – develops GIS tools; mostly computer science with some courses in GIS Solutions Developer – develops GIS applications that link GIS to real- world problems; mostly GIS/CS with some disciplinary expertise Systems Manager – develops and maintains spatial databases and connections within (LAN) and outside (Internet) the organization; CS and GIS balance Data Provider – develops GIS data layers; good skills in GPS and remote sensing with strong skills in GIS data formats and geodetic referencing GIS Specialist – uses discipline expertise and GIS knowledge for basic GIS applications and interacts with solution developers to address complex spatial problems General and Innovative Users – uses understanding of basic concepts, capabilities and considerations in developing new applications within their discipline “…of the Discipline ” “…of the Discipline ” (See Beyond Mapping III, Topic 4, “Where Is GIS Education”) Beyond Mapping IIIBeyond Mapping III The “bookends” of this continuum are the current drivers of Geotechnology

26. Vector to/from Raster (direct calculation) (Berry) V to R – burning the points, lines and areas into the grid (fat, thin and split) R to V – connecting grid centroids, sides and edges (line smoothing)

27. Vector to Raster (centroid implied) (Berry) Vector Map (polygons) V to R – uses a point file of cell centroids and converts polygon features that intersect Implied Grid with Centroids Note: this technique is very sensitive to cell size (features smaller than cells) and complexity of boundary shape …but it is really fast Centroid Point File Raster Map The corresponding grid cell is assigned the value of the “point in polygon intersection” Polygons with Overlaid Points …as the points fall

28. just for fun (you are having fun, right?)— just for fun (you are having fun, right?)— Export the MapCalc Tutor25.rgs Elevation map layer in both ESRI GridASCII format and Surfer ASCII format (Berry) Exporting MapCalc Data Layers ESRI GridASCII Format …browse to an appropriate folder and Save exported file Surfer ASCII Format

29. (Berry) Grid-based Data Structures/Formats (Esri.asc) General Information (“header” first 6 records) …open the ELEV.asc file in Notepad to see the data structure (stored as an Individual File) …open the ELEV.asc file in Notepad to see the data structure (stored as an Individual File) #Row #Col Longitude of LL corner Latitude of LL corner Cell size (in decimal degrees) No Data value (null) Map Data (Bottom portion) Origin is upper- left corner …values along the row, left to right in a block (25) …next row up …repeat for all rows (625 total) Each block contains all of the map values for a row

30. (Berry) Grid-based Data Structures/Formats (Surfer.grd) General Information (“header” first 5 records) …open the ELEV.grd file in Notepad to see the data structure (stored as an Individual File) (stored as an Individual File) File Type #Row #Col Lon/Lat LL and UR Min and Max Value Map Data (Bottom portion) Origin is lower- left corner …values along the row, left to right in a block (25) …next row up …repeat for all rows (625 total) Each block contains all of the map values for a row

31. Grid-based Data Structures/Formats (MapCalc.rgs) (Berry) …open the Tutor25.rgs in Notepad to see the data structure (stored as a Data Table) …open Tutor25.rgs in Notepad General and Map Legend Information (top portion) Map Data (Bottom portion) Origin is lower- left corner …values for all columns along the row, left to right (25) …next row up …repeat for all rows (625 total) Each column contains all of the map values for a layer Single database table with map name, units, default display settings and creation history as serial header