Created by Lisa Bingham University of Stavanger, Norway Maps and GIS Created by Lisa Bingham University of Stavanger, Norway Lisa Bingham Lisa.bingham@uis.no Contact for questions, list of readings used in course, and labs or other assignments. Course originally planned for a 12-week Bachelor of Science degree in Petroleum Geoscience Engineering

Course Objectives Read, understand, and interpret maps Basic understanding of GIS Basic understanding of GPS

http://img.moonbuggy.org/the-road-to-success/

Reading a map

Reading maps Maps relate information Investigate the map It is up to the viewer to interpret the information How? Investigate the map Identify the parts of the map Familiarize yourself with the map Are there graphs? Inset maps? Additional figures? What is the purpose of the map? What does the map tell you? What information does it relate?

What makes a “good” map? Defined purpose and audience. These influence what makes a “good” map for the intended audience. tourist vs. geologist Avoid cluttering or over-complications Legible labeling Coloring and patterns should follow cartographic conventions.

Features of a map A concise map title An easy to read scale bar An easy to read legend, if necessary North arrow if the coordinate system is not clear or if the map is turned to an angle Legible coordinates at the border of the map Projection information

Identify the parts of a map Locate: Title Scale Scale bar Legend Coordinate system or grid markings Location or inset map Publication information

publication information Where is the title? Title Where is the legend? Where is the inset map? Where is the scale bar? Scale Scale bar Where is the scale? Where are the grid coordinates? Where is the north arrow? Where is the publication information? Compiler and publication information Where are the graphs? Some maps have north arrows or compass roses, or may include projection information. This map does not. Legend Inset map Grid coordinates Graphs

Familiarize yourself with the map.

What does the map tell you? Mineral-rich in the north Mineral-poor in the center Minerals in the south What does the map tell you? Diamonds with gold in the northeast Gold in north-central If you represented a mining company, where would you look for: gold? diamonds? bauxite? radioactive minerals? Mica-rich in the south Diamond production decreasing

Understanding Map Scales Representations: verbal (1 map centimeter represents 30,000 ground centimeters) fraction (1:25,000) graphic (scale bar) Map scale indicates how much a given distance was reduced to be represented on the map.

Understanding Map Scales Small-scale map depicts large areas, so low resolution. 1:10,000,000

Understanding Map Scales Large-scale map depicts small areas, so high resolution. 1:50,000 1,267 inches to 1 mile

Small-scale vs. Large-scale Maps When the scale is written as a fraction, is the fraction very small or very large? 1/1,000 1/100,000 1/1,000,000 1/5,000,000 1/10,000,000 Identifying a map as small- or large-scale is an exercise of relativity

Reading Map Contours First familiarize yourself with the map Locate the contour interval Investigate the contours Are they close together? Far apart? Are the very straight? Are there many concentric circles? Do the contours shape like V’s or U’s?

Elevation Contour

What can be said about the elevation in this area (northeast corner of the previous map)?

What can be said about the elevation in this area (northeast corner of the previous map)? V shape Steep slopes Coastline V shape Less steep area

What can be said about the elevation in this area (central area of the large map)?

Steeper area with very curvy contours High point or depression? What can be said about the elevation in this area (central area of the large map)? Flat area Coastline Flat area Steeper area with very curvy contours High point or depression?

High point or depression?

Understanding Coordinate Systems

What is a coordinate system? A mathematical system used to explain the location of a point on the earth (or other planet). A geographic coordinate system is used to assign geographic locations to objects. A global coordinate system of latitude-longitude is one such framework. Another is a planar or Cartesian coordinate system derived from the global framework.

Latitude facts: Lines of latitude (parallels) are evenly spaced from 0o at equator to 90o at poles. 60 nautical miles (~ 110 km)/1o, ~1.8 km/minute and ~ 30 m/second of latitude. N. latitudes are positive, S. latitudes are negative. Equator From M. Helper, University of Texas, 2008

Longitude facts: Lines of longitude (meridians) converge at the poles; the distance of a degree of longitude varies with latitude. Zero longitude is the Prime (Greenwich) Meridian (PM); longitude is measured from 0-180o east and west of the PM. East longitudes are positive, West longitudes are negative. P.M. 180o From M. Helper, University of Texas, 2008

Units of Measure Decimal degrees (DD), e.g. - 90.50o, 35.40o order by longitude, then latitude Format used by ArcGIS software Degrees, Minutes, Seconds (DMS), e.g. – 90o 30’ 00”, 35o 24’ 00” From M. Helper, University of Texas, 2008

What is a map projection? A map projection is used to portray all or part of the round Earth on a flat surface. This cannot be done without some distortion. Every projection has its own set of advantages and disadvantages. There is no "best" projection. The mapmaker must select the one best suited to the needs, reducing distortion of the most important features.

Laying the earth flat Why? Need convenient means of measuring and comparing distances, directions, areas, shapes. Traditional surveying instruments measure in meters or feet, not degrees of longitude and latitude. Globes are bulky and can’t show detail. 1:24,000 globe would have diameter of ~ 13 m Typical globe has scale of ~ 1:42,000,000 Distance & area computations more complex on a sphere. From M. Helper, University of Texas, 2008

Laying the earth flat How? Using projections – transformation of curved earth to a flat map; systematic rendering of the longitude and latitude graticule to rectangular coordinate system. Scale 1: 42,000,000 Scale Factor 0.9996 (for specific points) Map Earth Globe Globe distance Earth distance Map distance Globe distance Mercator Projection From M. Helper, University of Texas, 2008

Inflatable globe demonstration Blown up and Cut up Use a beach ball globe to demonstrate the flattening of a globe. Start with a blown up beach ball. Let the students investigate. Then show a cut up beach ball. You could if you have the resources, cut the ball in front of the students.

Laying the earth flat Systematic rendering of Latitude (f) & Longitude (l) to rectangular (x, y) coordinates: y 0, 0 x Geographic Coordinates (f, l) Projected Coordinates (x, y) Map Projection From M. Helper, University of Texas, 2008

Laying the earth flat “Geographic” display – no projection x = l, y = f Grid lines have same scale and spacing l f y x From M. Helper, University of Texas, 2008

“Geographic” Display Distance and areas distorted by varying amounts (scale not true); e.g. high latitudes l f y x From M. Helper, University of Texas, 2008

Projected Display E.g. Mercator projection: f x = l 90 5+ E.g. Mercator projection: x = l y = ln [tan f + sec f] y From M. Helper, University of Texas, 2008

Laying the earth flat How? Projection types: Orthographic Gnomonic Stereographic a A’ A’ A’ a a T’ T’ T’ T T T b B’ B’ b b B’ From M. Helper, University of Texas, 2008

Inflatable globe demonstration Light shines through Use a beach ball that has the top cut out. Dangle a light bulb inside and outside.

Projection produces distortion of: Distance Area Angle Shape Distortions vary with scale; minute for large-scale maps (e.g. 1:24,000), gross for small-scale maps (e.g. 1: 5,000,000) Goal: find a projection that minimizes distortion of property of interest From M. Helper, University of Texas, 2008

How do I select a projection? Scale is critical – projection type makes very little difference at large scales For large regions or continents consider: Latitude of area Low latitudes – normal cylindrical Middle latitudes – conical projection High latitudes – normal azimuthal Extent Broad E-W area (e.g. US) – conical Broad N-S area (e.g. S. America) – transverse cylindrical Theme e.g. Equal area vs. conformal (scale same in all directions) From M. Helper, University of Texas, 2008

How to know which map projection to use? General guide: http://erg.usgs.gov/isb/pubs/MapProjections/projections.html Conventions for different areas or fields of study

Overall View of GIS

Key Questions and Issues What is GIS? What are the applications of GIS? How is the real world represented in GIS? What analyses can GIS perform?

What does GIS stand for? GIS is an acronym for “Geographic Information System”

What is GIS? Computerized management and analysis of geographic information Group of tools (and people) for collection, management, storage, analysis, display and distribution of spatial data and information Computer-based tool for mapping and analyzing things that exist and events that happen Refer to readings for other definitions From M. Helper, University of Texas, 2008

GIS Software There are several GIS software programs available for use. Open source (not necessarily free) MapServer TerraView Quantum GIS UDig Proprietary software IDRISI GMT Manifold MapPoint ESRI (used in class)

GIS Example From M. Helper, University of Texas, 2008

A GIS is Composed of Layers Geology DEM Digital elevation model Hydrography Roads From M. Helper, University of Texas, 2008

Features have locations Stavanger X = 638539 m Y = 8135093 m X axis Origin (0, 0) Y axis From M. Helper, University of Texas, 2008

Spatial relationships can be queried What crosses what? Proximity – What is within a certain distance of what? Containment - What’s inside of what? Which features share common attributes? Many others From M. Helper, University of Texas, 2008

Remember GIS focuses on geographic information If something has a location or is associated with a location, it can be mapped.

Key Questions and Issues What is GIS? What are the applications of GIS? How is the real world represented in GIS? What analyses can GIS perform?

The Global Positioning System From M. Helper, University of Texas, 2008

GPS Facts of Note Today ~30 satellites for GPS USA Department of Defense navigation system First launch on 22 Feb 1978 Originally 24 satellites Today ~30 satellites for GPS From M. Helper, University of Texas, 2008

GPS Milestones 1978: First satellites launched 1983: GPS declassified 1989: First hand-held receiver 1991: S/A activated (large error in location) 1993: GPS constellation fully operational 1995-1996: First hand-held, “mapping-grade” receivers 1996-1998: GPS on a microchip 1997: First $100 hand-held receiver 2000: S/A off (more accuracy) GPS – Milestones 1978: First 4 satellites launched 1983: GPS declassified - Korean airliner shot down over Soviet airspace - first civilian receivers 1986-1989: Challenger Disaster hiatus 1989: First hand-held receivers – Magellan 1991: S/A activated; DGPS becomes essential for surveying and mapping 1993: I buy my first GPS receiver – Trimble Scout 1993: GPS constellation full operational status (24 SVs; 5-8 visible anywhere, anytime) 1995-1996: First hand-held, “mapping-grade” receivers (DGPS capable, data dictionary). 1996-1998: GPS on a chip developed –receivers can use external CPUs 1997: First hand-held receivers for under $100 2000: integration of GPS and cellular technology 2000: SA is turned off; inexpensive GPS receivers horizontal accuracy increased from ~ 100 meters to 15-25 meters – detailed mapping with a single receiver possible 2003: FAA commissions WAAS – Free wide-area DGPS - properly equipped receiver can obtain horizontal precision of 1.5-3 m, vertical precision of 7 m. “Survey-grade” equipment no longer needed for all but most precise work. From M. Helper, University of Texas, 2008

GPS Segments Space – Satellites (SVs). Control – Ground stations track SV orbits and monitor clocks, then update this info for each SV, to be broadcast to users. User – GPS receivers convert SV signals into position, velocity and time estimates. From M. Helper, University of Texas, 2008

How are SV and receiver clocks synchronized? Clock errors will cause spheres of position (solid lines) to miss intersecting at a point. Adjust receiver clock slightly forward will cause larger DT(=larger sphere; dashed) and intersection at point. Requires 4 SVs, not 3 as shown, for clock error & X, Y, Z From M. Helper, University of Texas, 2008

Satellite Positioning Observe DT Orbit Known Determine Geocenter From M. Helper, University of Texas, 2008

3-D (X, Y, Z) One-way Ranging Intersection of 2 spheres of position yields circle Intersection of 3 spheres of position yields 2 points of location One point is position, other is either in space or within earth’s interior With earth ellipsoid (4th sphere) Get receiver clock synchronized and X & Y but no Z Intersection of 4 spheres of position yields XYZ and clock synchronization From M. Helper, University of Texas, 2008

Tropospheric Delay (~ 0.5 m) Sources of Error Satellite Orbit Errors (~2.5 m) SV clock error (~1.5 m) L2 L1 50 km Ionospheric Refraction (~ 5 m) (Can correct with L1 & L2 DTs) 200 km Tropospheric Delay (~ 0.5 m) Multipathing (~0.5 m) + GDOP (errors x 4-6) (Geometric dilution of precision) From M. Helper, University of Texas, 2008

Satellite Constellation Must have a good spread of satellites http://en.wikipedia.org/wiki/File:ConstellationGPS.gif

GPS Resolution and Map Scales From M. Helper, University of Texas, 2008

Familiarization with GIS Software used is ESRI ArcGIS, but concepts are the same with any GIS software program.

Vector data

Vector data An x, y coordinate system references the real-world location. Shapefiles and feature classes (file types) are vector data. Appropriate for discrete data where boundaries are needed. Pipeline location.

Raster data

Raster data Assign a value to a cell.

Raster data Raster data may be a georeferenced jpg or tiff, or a converted ASCII grid. Appropriate for continuous data where discrete boundaries are not necessary. Topography Grid files Cells contain Z data. The smaller a cell size, the higher the resolution.

Practical uses of raster data Simple display of a raster Topography (elevation) Bathymetry (depth) Gravity Magnetic anomalies

Advanced uses of raster data Additional processing of raster Changes in morphology Sediment thickness Hill shades (Creating texture) Contours Topographic profiles Spatial analysis Map algebra

Using Satellite Data with GIS Oman http://www.satimagingcorp.com GPS Data Datapoints Tracks Remote Sensing Data Satellite images RADAR Beijing, China http://www.globalsecurity.org

Using Satellite Data with GIS Digitize buildings and roads Digitize faults, scarps, rivers, or elevation Beijing, China http://www.globalsecurity.org Oman http://www.satimagingcorp.com

ArcMap document Title bar Map area Table of contents Coordinates

Acquiring External Data Government and non-government agencies may provide free GIS data Quality Map purpose influences acceptable quality

General Websites: Shapefiles Norwegian Petroleum Directorate www.npd.no GIS Data Depot data.geocomm.com DIVA-GIS www.diva-gis.org/gdata Norwegian Geological Survey (NGU) www.ngu.no United States Geological Survey www.usgs.gov Many others

General Websites: X,Y Data (Need Converting) USGS NEIC Earthquake Database http://neic.usgs.gov/neis/epic/epic.html

General Websites: Grids (May Need Converting) General Bathymetric Chart of the Oceans (GEBCO) www.gebco.net CGIAR-CSI SRTM Processed NASA satellite topography data http://srtm.csi.cgiar.org/ Scripps Institution of Oceanography http://topex.ucsd.edu/marine_topo/ NGDC World Magnetic Anomaly Map www.geomag.us/models/wdmam.html

General Websites: Maps (Need georeferencing) The University of Texas at Austin Perry-Castañeda Library Map Collection www.lib.utexas.edu/maps/ Google Image search

Identify features Select the identify tool. Click on a feature.

Why select features? Create subsets Find data Find counts of data with certain attributes Find data near a location

Select by attributes Use Select by Attributes wizard Use when attribute values are known and assigned Can be unique

Select by location Use select by Location wizard Location with buffers What is a buffer? Location with respect to another dataset

Creating and editing shapefiles Not all data that is needed for a mapping project will be available in GIS format Some data is extremely expensive to buy Some data is not available for purchase Sometimes the GIS technician needs to create new data based on other map layers

Georeferencing

What is Georeferencing? It is a process by which locational information (geo) is added (reference) to an image (raster) in a GIS program. A point on the image is assigned a coordinate pair in two ways: By lining up the image to a feature By adding coordinates directly

For Example: Align raster image to vector data (shapefile or feature)

Nature of the problem: Data source registration may differ by: Rotation Translation Distortion Translation Rotation Differential Scaling Skew Distortion From M. Helper, University of Texas, 2008

General problem is then: Control Points “Displacement Link” (0,1) (1,1) (501000, 3725000) (0,0) (1,0) (498100, 3715000) Source (x, y) Destination (X’, Y’) (“Warp”) From M. Helper, University of Texas, 2008

What images to use? Trusted sources (published maps from map agencies) Clear coordinate system markings (Decimal degrees for Geographic Coordinate Systems; Meters for UTM and Mercator, but need a reasonable guess of UTM zone or Mercator) Clear country boundaries, city locations, major roads, major rivers

What images to discard? Sketchy sources (personal websites or unpublished sources) Blurry, coarse or very thick country boundaries. These are usually over-generalized. Maps that rely on other maps to show their locations (over-use of inset maps) Exceptions: Very old maps which are not available in an updated form!

Digitizing from Georeferenced Image Obtain information that has not been published in GIS Obscure publication or out-of-print publication Error margin depends on overall scale of data (global vs continental vs regional vs country/state vs town)

Practice: Good or Bad?

Practice: Good or Bad?