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

GIS ModelingGIS Modeling Week 2 — Maps as Data Week 2 — Maps as Data

GEOG 3110 –University of DenverGEOG 3110 –University of Denver

Points , lines, polygons and surfacesPoints , lines, polygons and surfacesDiscrete vs. Continuous dataDiscrete vs. Continuous data

Map data types and their implicationsMap data types and their implicationsDisplaying grid dataDisplaying grid data

Contouring implicationsContouring implicationsGrid map structure and storage Grid map structure and storage

Presented byPresented by Joseph K. BerryJoseph K. BerryW. M. Keck Scholar, Department of Geography, W. M. Keck Scholar, Department of Geography,

University of DenverUniversity of Denver

Who We Are Who We Are (Class Photo)(Class Photo)

Class WebsiteClass Website

www.innovativegis.com/basis/www.innovativegis.com/basis/Courses/GMcourse13/Courses/GMcourse13/

Course SyllabusCourse Syllabus

Who Should Take the CourseWho Should Take the Course? ?

About the instructorAbout the instructor

MapCalc ManualMapCalc Manual

Setting up and using class dataSetting up and using class data

Email dialog and other helpful hintsEmail dialog and other helpful hints

Homework guidelinesHomework guidelines and and example question/responseexample question/response

Report Writing TipsReport Writing Tips

Team Evaluation FormTeam Evaluation Form

Example Mini-ProjectExample Mini-Project

Class MakeupClass Makeup

Grading Policy and Grading Policy and LogisticsLogistics

What GIS Is What GIS Is (and isn’t)(and isn’t)

Computer Computer MappingMapping (70’s) (70’s) - - Spatial dB Spatial dB ManagementManagement (80’s)(80’s) - - GIS GIS ModelingModeling (90’s) (90’s)

Now, Where Were We?Now, Where Were We?

GIS ModelingGIS Modeling

……keeping in mind that the past decade was primarily focused on keeping in mind that the past decade was primarily focused on MultimediaMultimedia Mapping (00’s) Mapping (00’s)

……that radically changes our that radically changes our Map ParadigmMap Paradigm

Spatial StatisticsSpatial Statistics — — ““NumericalNumerical” relationships within ” relationships within

and among mapped data and among mapped data (Surface Modeling and (Surface Modeling and

Spatial Data Mining)Spatial Data Mining)

From mapping toFrom mapping toSpatial ReasoningSpatial Reasoning……

Spatial AnalysisSpatial Analysis — — ““ContextualContextual” relationships” relationships

within and among mapped within and among mapped

data data (Reclassify, Overlay, (Reclassify, Overlay,

Distance, Neighbors)Distance, Neighbors)

……but we but we didn’t finish didn’t finish last week’s last week’s material!!!material!!!

(Berry)(Berry)…the 2010s await characterization

Prefer Prefer Gentle SlopesGentle Slopes, , Near RoadsNear Roads, , Near WaterNear Water, , View of WaterView of Water and and Westerly OrientedWesterly Oriented …but can’t be …but can’t be too closetoo close to water or to water or too steeptoo steep

11

1) Base 1) Base mapsmaps

555) Constraint5) Constraintmapsmaps

66

6) Final map6) Final map

WorstRed

BestGreen

ConstrainedBlack

22

2) Derived 2) Derived mapsmaps

Algorithm

xx33

3) Interpreted3) Interpretedmapsmaps

Calibrate

xx44

4) Combined /4) Combined /Modeled mapModeled map

Weight

(Berry)(Berry)

Campground Suitability Model Review Campground Suitability Model Review (Logic)(Logic)

(Berry)(Berry)

Campground Suitability Model Review Campground Suitability Model Review (Solution)(Solution)

Solution set Solution set of maps are of maps are created by created by evaluating evaluating the model the model logic for the logic for the unique unique pattern of pattern of conditionsconditions at each at each geographic geographic location location

……grid cellgrid cell

A sequencing of map analysis commands are applied to implement model logic—A sequencing of map analysis commands are applied to implement model logic—using a command scriptusing a command script (Tutor25_Campground.scr)(Tutor25_Campground.scr)

From GIS as a From GIS as a ToolboxToolbox enabling display and geo-enabling display and geo-queryquery…

Spatial Data Spatial Data vs.vs. Spatial InformationSpatial Information

Compaq II Compaq II Portable ComputerPortable Computer

Summagraphics Summagraphics Bit Pad DigitizerBit Pad Digitizer

Consultant Heaven

Consultant Hell

to a to a SandboxSandbox for developing, communicating, for developing, communicating, interacting and evaluating solutions to complex interacting and evaluating solutions to complex spatial problems—spatial problems—

……from from WhereWhere is is WhatWhat to to So WhatSo What, , WhyWhy and and What IfWhat If

Infusing Stakeholder Infusing Stakeholder PerspectivesPerspectives

Spatial Reasoning and DialogueSpatial Reasoning and Dialogue

(digital slide show BB-BK)(digital slide show BB-BK)

Tropical Resources InstituteTropical Resources Institute Yale University — 1988Yale University — 1988

www.innovativegis.com/basis/BeyondMapping_I/Topic10/BM_I_T10.htm www.innovativegis.com/basis/BeyondMapping_I/Topic10/BM_I_T10.htm

(Berry)(Berry)

Manual cartography utilizes Manual cartography utilizes pointspoints, , lineslines and and areasareas as the basic as the basic building blocks for characterizing geographic spacebuilding blocks for characterizing geographic space

Basic Map FeaturesBasic Map Features

……traditionally all maps are composed of three fundamental map features—Points, Lines 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 and Areas. The digital map provides additional dimensions of depth and time to

extend the features to extend the features to SurfacesSurfaces, , VolumesVolumes, , hyper-Volumes hyper-Volumes and and fuzzy-Featuresfuzzy-Features

Based on spatial objects (discrete vector)

New map feature type based on

grid cells (continuous raster) Grid-based Grid-based

mapped datamapped data

(Berry)(Berry)

Storing Points, Lines and AreasStoring Points, Lines and Areas

……how do you think Vector and Raster data structures storehow do you think Vector and Raster data structures storeSurfacesSurfaces, , VolumesVolumes,, hyper-Volumes hyper-Volumes andand fuzzy-Features fuzzy-Features??

(Berry)(Berry)

……replaced by the concept of replaced by the concept of ResolutionResolution (Spatial, Mapping, Thematic and Temporal)(Spatial, Mapping, Thematic and Temporal)

Spatial ResolutionSpatial Resolution

……heresy!!!heresy!!!The concept of The concept of ScaleScale Scale= MD / GD Scale= MD / GD (Map Distance / Ground Distance)(Map Distance / Ground Distance)

(Berry)(Berry)

but this is a property of the display medium but this is a property of the display medium and and does notdoes not exist in a GIS database exist in a GIS database

Minimum Mapping ResolutionMinimum Mapping Resolution


(Berry)(Berry)

Thematic and Temporal ResolutionsThematic and Temporal Resolutions

……so what is the difference between the concepts of so what is the difference between the concepts of PRECISIONPRECISION and and ACCURACYACCURACY

……and how do these concepts relate to the concept of and how do these concepts relate to the concept of RESOLUTIONRESOLUTION??


(Berry)(Berry)

Handheld GPS unitHandheld GPS unit

Precision GPS unitPrecision GPS unit

AccuracyAccuracy vs. vs.

PrecisionPrecision

……the “target analogy” the “target analogy” compares measurements compares measurements to the pattern of arrows to the pattern of arrows shot at a targetshot at a target

Accuracy versus PrecisionAccuracy versus PrecisionThe Wikipedia defines The Wikipedia defines Accuracy Accuracy as “the degree of veracity” (as “the degree of veracity” (exactnessexactness) while ) while PrecisionPrecision as “the degree of as “the degree of

reproducibility” (reproducibility” (repeatablerepeatable) )

HighHigh Accuracy Accuracy

but but LowLow Precision Precision

HighHigh Precision Precision

but but LowLow Accuracy Accuracy

AccuracyAccuracy describes the describes the closeness of arrows to the bull’s-eyecloseness of arrows to the bull’s-eye at the target center (actual/correct) at the target center (actual/correct)

PrecisionPrecision relates to the relates to the size of the cluster of arrowssize of the cluster of arrows— grouped tightly together is considered precise— grouped tightly together is considered precise

(Berry)(Berry)

Vegetation Vegetation Parcel Parcel

MappingMapping

PrecisionPrecision = delineation ( = delineation (WhereWhere))

Interpreter AInterpreter BInterpreter C

Classification versus Delineation Classification versus Delineation (spatial perspective)(spatial perspective)

Classification Classification Accuracy Accuracy ((WhatWhat) ) Delineation Delineation PrecisionPrecision ( (WhereWhere) ) ……so what is the interpretation of so what is the interpretation of PRECISIONPRECISION andand ACCURACYACCURACY for for remote sensing Classification Mapsremote sensing Classification Maps??

AccuracyAccuracy = classification ( = classification (WhatWhat))

Photo Interpreter ACottonwood

Photo Interpreter CCottonwood

Photo Interpreter BPonderosa Pine

…different Classifications

…different interpretation Boundaries

(Berry)(Berry)

HomeownersHomeowners EnvironmentalistsEnvironmentalists EngineersEngineersHD & VE times 10HD & VE times 10 RP & SA times 10RP & SA times 10 HD & RP times 10HD & RP times 10

StartStart

EndEnd

EngineersEngineers

EnvironmentalistsEnvironmentalists

HomeownersHomeowners

IndividualIndividualSolutionsSolutions

Model Accuracy/Precision Model Accuracy/Precision (spatial modeling perspective)(spatial modeling perspective)

CalibrateCalibrate

ExpertExpertOpinionOpinion

……cognitive cognitive mapping has mapping has no definitiveno definitive right/wrongright/wrongsolution—solution—

Most Most Preferred Preferred

WeightWeight

StakeholderStakeholderValuesValues

CombinedCombinedSolutionSolution

StartStart

EndEnd

Average of the three cost

surfaces

Optimal Path

Optimal Corridor

MostMostPreferredPreferred

LeastLeastPreferredPreferred

Routing CriteriaRouting Criteria

1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 Housing DensityHousing Density Road ProximityRoad Proximity Sensitive AreasSensitive Areas Visual ExposureVisual Exposure

(Berry)(Berry)

GIS Maps contain—• Points, lines, polygons• Grid surfaces • Raster images• Pseudo grids

RasterRaster

data types —data types — grid surfacesgrid surfaces,, raster images raster images andand pseudo gridspseudo grids — treat — treat space in entirely different manner to portray space in entirely different manner to portray spatially continuous dataspatially continuous data

Raster Data TypesRaster Data Types

…mapped data ready for map analysis and modeling— unconstrained double precision value (+/- decimal)

Map

Layer

……in ain a raster imageraster image (aka photo) (aka photo) the values stored the values stored at each map location identify its color (hue, at each map location identify its color (hue, saturation and brightness)– saturation and brightness)– constrained integer valueconstrained integer value (0-255) (0-255)

……in ain a pseudo gridpseudo grid each each grid element is grid element is treated as a separate polygontreated as a separate polygon (square) with (square) with

spatial and attribute tables defining the set of spatial and attribute tables defining the set of little polygons— primarily used for “walking” little polygons— primarily used for “walking”

information between Grid and Vector systemsinformation between Grid and Vector systems

It is important to note that the map features in a It is important to note that the map features in a vector-basedvector-based mapping system mapping system identify identify discrete, irregular spatial objects with sharp abrupt boundariesdiscrete, irregular spatial objects with sharp abrupt boundaries. .

(Berry)(Berry)

Grid MapGrid Map

A A Grid MapGrid Map consists of a matrix of numbers with a value consists of a matrix of numbers with a value indicating the characteristic /condition at each grid cell indicating the characteristic /condition at each grid cell locationlocation

Map Stack ……forming a geo-registered set of forming a geo-registered set of Map Layers Map Layers oror

“ “Map StackMap Stack””

Basic Grid Data StructureBasic Grid Data Structure

Analysis Frame Analysis Frame provides consistent provides consistent “parceling” needed “parceling” needed for map analysis for map analysis and extends and extends discretediscrete Point, Line Point, Line and Areal features and Areal features to cto continuousontinuous Map Map SurfacesSurfaces

(Berry)(Berry)

Data listing for aMap Stack

Drill-down

Col 3, Row 22Col 3, Row 22

Analysis FrameAnalysis Frame

Continuous Mapped Data

Basic Grid Display TypesBasic Grid Display Types

Display TypesDisplay Types……

LatticeLattice display display forms a forms a smooth wireframesmooth wireframe

GridGrid display display forms forms chunky extruded gridschunky extruded grids

(See Example Applications, “Display Types” for more information)(See Example Applications, “Display Types” for more information)

……so how is a so how is a Contour MapContour Map generated? generated? (vector representation of a surface)(vector representation of a surface)

Contour line

1900

(Berry)(Berry)

Thematic Display Thematic Display (Shading Manager)(Shading Manager)

(See Example Applications, “Display Types” for more information)(See Example Applications, “Display Types” for more information)

MapCalc Shading ManagerMapCalc Shading Manager……

# Ranges# Ranges sets the sets the number of intervalsnumber of intervals Equal RangesEqual Ranges has the has the same range for each intervalsame range for each interval

(or (or Equal CountEqual Count has has the same number of cells for each intervalthe same number of cells for each interval))

(Berry)(Berry)

Contouring Mapped Data Contouring Mapped Data (Display Mode)(Display Mode)

Display the elevation surface Display the elevation surface as wireframe (as wireframe (LatticeLattice) with filled ) with filled floor contoursfloor contours

Set #Ranges to Set #Ranges to 77 and assign and assign yellow as the inflection coloryellow as the inflection color

Redisplay the surface as Redisplay the surface as Equal CountEqual Count, , Equal RangesEqual Ranges, ,

StDevStDev and and User DefinedUser Defined(Natural Breaks?)(Natural Breaks?)

+/- 1Stdev+/- 1StdevEqual CountEqual Count Equal RangesEqual Ranges

……note the note the dramatic differencesdramatic differences in in the shape and position of the boundary the shape and position of the boundary lines of the discrete contour intervalslines of the discrete contour intervals

User Defined User Defined (300 Step)(300 Step)

So which discrete contour map of the elevation surface is So which discrete contour map of the elevation surface is CORRECTCORRECT?? …are the differences in …are the differences in PrecisionPrecision and/or and/or AccuracyAccuracy??(Berry)(Berry)

Matching Data Types & Display Types/FormsMatching Data Types & Display Types/Forms

(See Example Applications, “Data Types”, “Color Interval/Pallet”, “3D Display Options” and “Data Inspection and Charting” for related information)(See Example Applications, “Data Types”, “Color Interval/Pallet”, “3D Display Options” and “Data Inspection and Charting” for related information)

3D Toggle3D Toggle changes changes 2D2D and and 3D3D display display formsforms

Display FormDisplay Form……

Use CellsUse Cells toggles toggles between between LatticeLattice and and GridGrid display types display types

Display TypeDisplay Type……

Data TypeData Type toggles toggles between between DiscreteDiscrete and and ContinuousContinuous data types data types

Data TypeData Type……

(Berry)(Berry)

Numeric and Geographic Data TypesNumeric and Geographic Data Types ……all digital maps are composed of organized sets of numbers— all digital maps are composed of organized sets of numbers—

the the Data TypeData Type determines what “map-ematical” processing can be done determines what “map-ematical” processing can be done with the numbers on an individual map or stack of map layerswith the numbers on an individual map or stack of map layers

““Numbers” in Numbers” in

Data SpaceData Space

““Numbers” in Numbers” in

Geographic Geographic SpaceSpace

(Berry)(Berry)

Homework Exercise #2Homework Exercise #2

Part 1Part 1 – – Understanding Basic Concepts and Terms Understanding Basic Concepts and Terms

• Scale and ResolutionScale and Resolution. 1. 1) Map Scale, 2) Spatial Resolution, 3) Thematic ) Map Scale, 2) Spatial Resolution, 3) Thematic Resolution, 4) Minimum Mapping Resolution and 5) Temporal Resolution.Resolution, 4) Minimum Mapping Resolution and 5) Temporal Resolution.

• Data TypesData Types.. 1) Nominal, 2) Ordinal, 3) Interval, 4) Ratio, 5) Binary, 6) Choropleth, 1) Nominal, 2) Ordinal, 3) Interval, 4) Ratio, 5) Binary, 6) Choropleth, 7) Isopleth data types (be sure to distinguish which data types are 7) Isopleth data types (be sure to distinguish which data types are NumericNumeric and which are and which are GeographicGeographic) )

• Display ConsiderationsDisplay Considerations.. You will generate different map displays of the Slope You will generate different map displays of the Slope and Districts map layers, then identify/comment on the and Districts map layers, then identify/comment on the Data TypeData Type, , Display TypeDisplay Type and and Display Display FormForm used and discuss the effects/appearance of the different displays used and discuss the effects/appearance of the different displays

Part 2Part 2 – – Characterizing Geographic Space Characterizing Geographic Space …Discrete versus Continuous…Discrete versus Continuous

• Thematic MappingThematic Mapping.. You will use the Shading Manager to create different map displays You will use the Shading Manager to create different map displays

while investigating the effects of while investigating the effects of Calculation ModeCalculation Mode (Equal Ranges, Equal Count,+/- 1 Standard Deviation (Equal Ranges, Equal Count,+/- 1 Standard Deviation and User Defined), and User Defined), Number of RangesNumber of Ranges and and Color RampColor Ramp assignments. assignments.

(Berry)(Berry)

Simple Erosion ModelSimple Erosion Model

(Exercise #2, (Exercise #2, Part 3Part 3))

Create a Create a slope mapslope map

Reclassify that map Reclassify that map for for slope classesslope classes

Create a Create a flow mapflow map

Reclassify that map Reclassify that map for for flow classesflow classes

Combine Combine the maps of the maps of slope classes and flow slope classes and flow classesclasses

……result is a map with a result is a map with a 2-digit code2-digit code

11StSt digit = flow class digit = flow class22ndnd digit = slope class digit = slope class

(Berry)(Berry)

So Where Are You in GIS?So Where Are You in GIS?

“…“…of the of the ComputerComputer”” “…“…of the of the ApplicationApplication””

……changing our changing our Map ParadigmMap Paradigm

ComputerComputerProgrammerProgrammer– –

develops GIS develops GIS toolstools; mostly ; mostly computer science computer science with some with some courses in GIScourses in GIS

Solutions Solutions DeveloperDeveloper– –

develops GIS develops GIS applicationsapplications that that link GIS to real-link GIS to real-world problems; world problems; mostly GIS/CS mostly GIS/CS with some with some disciplinary disciplinary expertiseexpertise

Systems Systems ManagerManager– –

develops and develops and maintains spatial maintains spatial databasesdatabases and and connections connections within (LAN) within (LAN) and outside and outside (Internet) the (Internet) the organization; CS organization; CS and GIS balanceand GIS balance

Data Data ProviderProvider– –

develops GIS develops GIS data layersdata layers; good ; good skills in GPS and skills in GPS and remote sensing remote sensing with strong skills with strong skills in GIS data in GIS data formats and formats and geodetic geodetic referencingreferencing

GIS GIS SpecialistSpecialist– –

uses discipline uses discipline expertise and expertise and GIS knowledge GIS knowledge for basic GIS for basic GIS applications and applications and interacts with interacts with solution solution developers to developers to address complex address complex spatial problemsspatial problems

General and General and Innovative UsersInnovative Users– – uses uses understanding of basic understanding of basic concepts, capabilities and concepts, capabilities and considerations in developing considerations in developing new applications within new applications within their disciplinetheir discipline

“… “…of the of the DisciplineDiscipline” ”

(See Beyond Mapping III, Topic 4, “Where Is GIS Education”)(See Beyond Mapping III, Topic 4, “Where Is GIS Education”)

The “The “bookendsbookends” of this continuum are ” of this continuum are the current drivers of Geotechnologythe current drivers of Geotechnology

(Berry)(Berry)

Vector to/from Raster Vector to/from Raster (direct calculation)(direct calculation)

V to RV to R– burning the points, lines and areas into the grid – burning the points, lines and areas into the grid (fat, thin and split)(fat, thin and split)

R to VR to V– connecting grid centroids, sides and edges – connecting grid centroids, sides and edges (line smoothing)(line smoothing)

(Berry)(Berry)

Vector to Raster Vector to Raster (centroid implied)(centroid implied)

Vector Map (polygons)Vector Map (polygons)

V to RV to R– uses a point file of cell centroids and converts polygon features that intersect– uses a point file of cell centroids and converts polygon features that intersect

Implied Grid with CentroidsImplied Grid with Centroids

NoteNote: this technique : this technique is very sensitive to is very sensitive to cell sizecell size (features (features smaller than cells)smaller than cells)and complexity of and complexity of boundary shapeboundary shape

……but it is but it is really fastreally fast

Centroid Centroid Point FilePoint File

Raster MapRaster Map

… … the corresponding the corresponding grid cells are assigned grid cells are assigned the value of the “the value of the “point point in polygon intersectionin polygon intersection””

Polygons with Overlaid PointsPolygons with Overlaid Points

……as the as the points fallpoints fall

(Berry)(Berry)

just for fun (you are just for fun (you are having fun, right?)—having fun, right?)—

Export the MapCalc Tutor25.rgs Export the MapCalc Tutor25.rgs Elevation map layer in both Elevation map layer in both

ESRI GridASCIIESRI GridASCII format format andand

Surfer ASCIISurfer ASCII format format

Exporting MapCalc Data LayersExporting MapCalc Data Layers

ESRI GridASCII FormatESRI GridASCII Format

……browse to an browse to an appropriate folder and appropriate folder and

SaveSave exported file exported file

Surfer ASCII FormatSurfer ASCII Format(Berry)(Berry)

Grid-based Data Structures/FormatsGrid-based Data Structures/Formats (Esri .asc)(Esri .asc)

General Information General Information (“header” first 6 records)(“header” first 6 records)

……open the open the ELEV.ascELEV.asc file in Notepad to see the data structure (stored as file in Notepad to see the data structure (stored as an an Individual FileIndividual File) ) <export Elevation as <export Elevation as ESRI_elevation.ascESRI_elevation.asc and open in NotePad> and open in NotePad>

#Row#ColLongitude of LL cornerLatitude of LL cornerCell size (in decimal degrees)No Data value (null)

Map Data (Bottom portion)Map Data (Bottom portion)

Origin is upper-Origin is upper-left cornerleft corner

……values along values along the row, left to the row, left to right in a block right in a block (25) (25)

……next row upnext row up

……repeat for all repeat for all rows (625 total)rows (625 total)

Each block Each block contains all of contains all of the map values the map values for a rowfor a row

(Berry)(Berry)

Grid-based Data Structures/Formats Grid-based Data Structures/Formats (Surfer .grd)(Surfer .grd)

General Information General Information (“header” first 5 records)(“header” first 5 records)

……open the open the ELEV.grdELEV.grd file in Notepad to see the data structure file in Notepad to see the data structure (stored as an (stored as an Individual FileIndividual File) ) <export Elevation as <export Elevation as Surfer_elevation.grdSurfer_elevation.grd and open in NotePad> and open in NotePad>

File Type#Row #Col

Lon/Lat LL and UR

Min and Max Value


Origin is lower-Origin is lower-left cornerleft corner

……values along values along the row, left to the row, left to right in a block right in a block (25) (25)



Each block Each block contains all of contains all of the map values the map values for a rowfor a row

(Berry)(Berry)

Grid-based Data Structures/Formats Grid-based Data Structures/Formats (MapCalc .rgs)(MapCalc .rgs)

……open the Tutor25.rgs in Notepad to see the data structure open the Tutor25.rgs in Notepad to see the data structure (stored as a (stored as a Data TableData Table) ) …open …open Tutor25.rgsTutor25.rgs in Notepad in Notepad

General and Map Legend Information (top portion)General and Map Legend Information (top portion)


Origin is lower-Origin is lower-left cornerleft corner

……values for all values for all columns along columns along the row, left to the row, left to right (25) right (25)



Each column Each column contains all of contains all of the map values the map values for a layer for a layer

Single database table with map name, units, default display settings and creation history as serial header

(Berry)(Berry)

Documents

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