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Why cant I continue working on my project at home off my USB thumb drive

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A city planner might be interested in zoning conflicts such as industrial zones ... or most efficient delivery routes or the fastest travel route (connectivity) ... – PowerPoint PPT presentation

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Title: Why cant I continue working on my project at home off my USB thumb drive


1
Why cant I continue working on my project at
home off my USB thumb drive?
  • A .mxd (ArcMap document) doesn't store the data
    it shows - it stores references to the data
  • A .lyr (Layer file) file stores the symbols,
    rules, and the data to which the layer points
  • In other words, a .mxd points to .lyr files.

2
Today
  • Vector Data Model
  • spaghetti vs. topological vector data model
  • topological data model - how it works
  • some common vector data model formats
  • Raster Data Model
  • DEMs, DRGs, DLGs
  • raster-based digital terrain modeling
  • some common raster data model formats
  • R to V and V to R
  • Discuss Richard Pikes two articles
  • Do MicroDEM lab

3
Spatial understanding of A vs. B?
A
B
4
say you made a simple vector map
5
your data are spaghetti entered or digitized
sloppily
gaps
slivers
overshoots
under-shoots
6
  • Spaghetti structure
  • Small pieces of spaghetti for points
  • Longer pieces for lines
  • Spaghetti ends touching for polygons
  • Easy/fast to create looks good, but its not
    very smart, and its messy

7
Typical Situations

8
Typical Situations
overshoot, and what to do with it
this is ideal, but...
undershoot, and what to do
9
Vector Data Model
  • Topology What is it?
  • Topology is the mathematical method used to
    define spatial relationships. Without a topologic
    data structure in a vector based GIS, most data
    manipulation and analysis functions would not be
    possible.
  • Topology expresses explicit relationships
  • Your topological data know
  • Connectivity
  • Contiguity/adjacency
  • Direction
  • Nestedness

10
Vector Data Model
  • Topology
  • New terms
  • Arc or Link line b/t nodes
  • Node the point at the end of an arc and the
    point where arcs cross

node
arc or link
node
11
Vector Data Model
  • Topology
  • Assigns a number to all nodes and arcs
  • Assigns a letter or number to each polygon
  • Assigns length to arcs and area to polygons
  • Arcs have polygons to their LEFT and RIGHT
  • Arcs connect if they share a node

12
Vertices shape Arcs
  • Arcs start and end at nodes
  • Arc 1 goes from node 2 to node 1
  • Vertices determine shape of line
  • Nodes and vertices are stored as coordinate pairs

13
Polygons (and external polygons)
  • Polygon 2 is bounded by arcs 1 2
  • Arc 2 has polygon 1 on left and polygon 2 on
    right
  • Polygon 1 is the EXTERNAL POLYGON

14
Representing Data using topology
.
  • point (node)
  • single x,y coordinate pair
  • zero area
  • tree, oil well, label location
  • line (arc)
  • two (or more) connected x,y coordinates
  • road, stream
  • polygon
  • four or more ordered and connected x,y
    coordinates
  • first and last x,y pairs are the same
  • encloses an area
  • census tracts, county, lake

y2
Point 7,2
x7
Arc 7,2 8,1
Polygon 7,2 8,1 7,1 7,2
15
Node/Arc/ Polygon Attribute Data
II
1
Birch
2
Smith Estate
I
III
A35
A34
4
Cherry
IV
3
Attribute Data
Spatial Data
16
  • Topology - ADVANTAGES
  • Error detection (is polygon really closed)
  • Each arc stored only once (more efficient)
  • Perform analyses
  • Saves processing time
  • Model flow through connections of lines
  • Topology DISDVANTAGES
  • Extra cost and time initially
  • Must create topology
  • Topology must be updated when any feature is
    changed

17
  • Who cares about topology?
  • A biologist might be interested in the habitats
    that occur next to each other (contiguity)
  • A city planner might be interested in zoning
    conflicts such as industrial zones bordering
    recreation areas (contiguity)
  • Transportation network, telecommunication
    systems, river systems (connectivity)
  • To find optimum routings or most efficient
    delivery routes or the fastest travel route
    (connectivity)
  • To predict loading at critical points in a river
    channel
  • To estimate water flow at a bridge crossing that
    will result from heavy flood (connectivity)

18
Some Common Vector File Formats
  • Coverage vector data format introduced with
    ArcInfo in 1981
  • multiple physical files (12 or so) in a folder
  • proprietary no published specs ArcInfo
    required for changes
  • can be exported to a single E00 (E-zero-zero)
    file for transfer
  • Shapefile vector data format introduced with
    ArcView in 1993
  • comprise 3 (or more) physical files (with
    extension of .shp, .shx, .dbf), all of which must
    be present
  • openly published specs so other vendors can
    create shape files
  • Geodatabase format introduced with ArcGIS 8.0 in
    2000
  • Multiple layers saved in a singe .mdb (MS
    Access-like) file
  • proprietary, next generation spatial data file
    format
  • store only vector data
  • 9.2 switched from Personal Geodatabase (.mbd) to
    File Geodatabase (.gbd)
  • TIN (triangular irregular network) format
    introduced with ArcGIS 8.0 in 2000
  • Represents geographic surfaces as contiguous
    non-overlapping triangles
  • The vertices of each triangle are known data
    points (x,y)
  • Values in the third dimension (z) taken from
    surveys, topographic maps, or digital elevations
    models (DEMs)

19
GBF/DIME and TIGER
GBF/DIME model
TIGER model
Image Source Demers, Michael. N. (2000). 2nd Ed.
Fundamentals of Geographic Information Systems.
p. 113. fig 4.16.
20
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21
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22
TINS
  • TIN (Triangulate Irregular Network)
  • Show topography/surfaces
  • Show 3D perspectives
  • Use adjacent point data to create facets
  • Save storage space
  • Are topological
  • Mimic surfaces

23
TINS
  • TIN (Triangular Irregular Network)

24
TINS
  • TIN (Triangulate Irregular Network)

25
Digital Line Graph (DLG)
  • Files from the U.S. Geological Survey (USGS),
    includes transportation, hydrography, contours,
    and public land survey boundaries
  • Digital version of information printed on USGS
    topographical quadrangle maps
  • The first mass produced GIS data for public use
    in the world

26
Digital Line Graph (DLG)
  • Derived from aerial photos or manual/automated
    digitizing methods
  • DLG products
  • Large (124,000)
  • Intermediate (1100,000)
  • Small (12,000,000)

27
A great paper on DLGs
  • http//gis.esri.com/library/userconf/proc00/profes
    sional/papers/PAP691/p691.htm

28
Some features attributes on a DLG
  • Transportation
  • Roads and Trails
  • 1700001
  • Bridge abutment
  • 1700002
  • Tunnel portal
  • 1700004
  • Gate
  • 1700005
  • Cul-de-sac
  • 1700006
  • Dead end
  • 1700007
  • Drawbridge

1700212 Trail, 4WD 1700213 Footbridge
1700214 Road ferry crossing 1700215
Perimeter of parking area 1700217 Class 3,
divided by centerline 1700218 Class 3,
divided, lanes separated 1700219 Class 4, one
way 1700220 Closure line 1700221 Class 3,
one way 1700222 Road in transition 1700299
Processing line 1700401 Traffic circle
1700402 Cloverleaf or interchange 1700403
Tollgate 1700404 Weight station 1700405
Nonstandard section of road 1700406 Covered
bridge 1700613 In service facility, rest area
Railroads 1800001 Bridge abutment 1800002
Tunnel portal 1800003 Crossover 1800007
Drawbridge 1800201 Railroad 1800202
Railroad in street or road 1800204 Carline
1800205 Cog railroad, incline railway, logging
tram 1800207 Railroad ferry crossing
1800208 Railroad siding or spur 1800209
Perimeter or limit of yard 1800211 Closure
line 1800299 Processing line 1800400
Railroad station, perimeter of station 1800401
Turntable
1800402 Roundhouse Miscelaneous
Transportation 1900001 End of transmission
line 1900002 End of pipeline at oil or gas
field 1900003 End of pipeline at refinery,
depot, ... 1900004 Steel or concrete tower on
transmission line 1900201 Pipeline 1900202
Power transmission line 1900203 Telephone or
telegraph line 1900204 Aerial tramway,
monorail, or ski lift 1900206 Closure line
1900299 Processing line 1900300 Seaplane
anchorage 1900400 Power station 1900401
Substation
29
NEXT - Raster GIS
  • Raster data are well suited for
  • spatially continuous data
  • modeling environmental phenomena
  • Continuous data include pH, air pressure, temp.,
    salinity, slope, light reflecting off ground,
    elevation, ______, _______, _________.

30
Raster Data Models Basics
  • What are the grid values?
  • DEMs ?
  • DRGs ?
  • DOQs ?
  • Images (.bmp, .tif, .gif, .jpg) ?
  • Examples of non-physical surfaces are
  • 1) ________________?
  • 2) ________________?
  • 3) ________________?

31
DOQ
  • USGS Digital Orthophoto Quads
  • One-meter resolution
  • Shot at about 20,000 ft.
  • Georeferenced
  • Total US coverage
  • Updated every 5 10 yrs.
  • Grayscale values
  • DOQ Quarters (DOQQs) exist too!

32
DRG
  • Digital raster graphics (DRG)
  • Produced from 1995 to 1998 by USGS through a
    partnership with Land Information Technology
    Company, Ltd., of Aurora, Colorado. The objective
    of the program was to scan all USGS standard
    quadrangle maps quickly and at low cost.

33
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34
DEM(digital elevation model)
  • A sampled array of elevations at regularly spaced
    intervals
  • 170,000 points on typical 124,000 30 Meter DEM
  • 54,000 for lower 48
  • 3,000 for Hawaii, Alaska, Puerto Rico
  • File Size
  • About 7 MB for 10 meter
  • About ½ to 1 MB for 30 meter

35
DEM
36
The latest DEMs offered by USGS
  • Shuttle Radar Topography Mission (SRTM)
  • 30 Meter - Data available for contiguous US,
    Hawaii and southern Alaska
  • 90 Meter - Extensive coverage including South
    America and most of North America
  • National Elevation Dataset (NED) through The
    Seamless Data Distribution System (SDDS)
  • 3 meter resolution limited to select areas of
    Washington state
  • 10 meter res. available covering most of the
    contiguous US
  • 30 meter res. for all of the United States
  • Some LiDAR
  • For select areas of US -- see the links below to
    find LiDAR data!

http//seamless.usgs.gov/
http//ned.usgs.gov/
37
SRTM coverage map
38
With DEMs and GIS, you can calculate
  • Elevation
  • Slope
  • Aspect
  • Profile
  • Hillshade
  • Line of sight
  • Viewshed
  • Surface area
  • Volume


primary parameters
39
Slope
  • Rise/Run (vertical dist./horizontal dist.)
  • Uses of slope
  • watershed drainage
  • biological
  • planning
  • hazards
  • recreation

40
Slope map
41
Aspect
  • Direction (0 360) of the slope
  • Uses of aspect
  • biological
  • planning
  • solar radiation/evaporation

42
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43
Hillshade
  • Hillshade sets view angle and assigns a
    brightness value to the slopes. Hillshade mimics
    natural lighting.
  • Uses of hillshade
  • Uses light to create visualizations of terrain

44
Hillshade
45
Hillshade
46
Elevation Transects (profiles)
47
Elevation Transects (with line of sight)
48
Viewsheds
Simulation image of proposed mine taken from
North Creek Rd just north of Wilsey Rd.
49
Surface Area
50
Volume
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