EPS 101/271 Lecture 10: Introduction to Digital Mapping Systems What are Digital Mapping Systems ? What are their educational and professional advantages ? How mapping software works: the visual user interface of GeoMapper/PenMap Digital base maps GPS devices (theory) An exciting advance with Classroom overview of many rewards, requires GeoMapper use in the field paying attention, following Lecture directions, personal Demonstration responsibility, and respect for Student use equipment – eg. UCSB What is Digital Mapping ? Mapping using digital electronics and information technology (IT) tools: (pen tablet portable PC’s and digital base maps) How different is it from Geographic Information Systems (GIS) ? GIS have 2 sources of information: - primary (newly-created data) made by digital or conventional mapping methods - secondary (digitizing old -existing data) until now GIS has largely dealt with secondary data 1 Purposes of Digital Mapping: Is the front end or data capture part of GIS systems- creating primary information Mapping- implementing the science of geology Increase overall productivity of mappers by improving: Accuracy in positioning (location) SdfSpeed of mapp ing Assisted standardization Integration of a variety of digital base maps Improved 3-D visualization & interpretation One-step “paperless” map production Educational Goals: Provide an enabling technology to advance the learning process of mapping and synthesis Reduce uncertainties and hesitancy to commit ideas to a map b ecause of diffi cu lti es i n positioning Improve mapping skills so that confidence builds as successful experiences reinforces skills Encourage insightful use of available IT data, not entertain students with mere gadgets Better preparation for professional careers 2 Educational strategy: Initiate teaching mapping using traditional paper and pencil methods Simple, fast, inexpensive- shows what is out there Digital instrumentation can interfere with learning basic geological skills and concepts Transition to digital mapping tools Use project oriented discovery learning- not show and tell Components Color pen table PC computer: Fujitsu Stylisitc 5000 Pen Tablet PC, 1.2GHz/10.4”reflective screen, 512 MB Memory 40 GB hard drive Mapping program (GeoMapper of UC Berkeley and PenMap of Strata Software, Bradford, England) Digital media Base maps: topographic, color orthophotos, epicenters EPS 118- plus gravity, magnetics, glacial geology, epicenters Real-time GPS for each student team integrated with mapping program and digital maps (not hand-held GPS) 3 Turn brightness to zero when outdoors- extend battery life and use only solar power Turn sounds off to extend battery life 4 US GlobalSat BC 337 GPS GPS http://www.usglobalsat.com/p-140-bc-337.aspx Frequency: L1, 1575.42MHz US Globalsat BC-337 GPS receiver with compact flash 20 channel AT-65 external antenna GPS accuracy depends on: Type of GPS unit The number of satellites visible to the receiver Strength of satellite signals (S/N) Geometric position of satellite in the sky (constellation) Differential corrections- require an unobstructed view of the southern sky- suggestion: put your external GPS antenna on your shoulder Face north when taking GPS readings- this automatically gives you the best chance of receiving the DGPS signals. 5 6 Satellite Geometry given as: HDOP = Horizontal dilution of precission Good GPS fix but Not differentially corrected 7 HGOP =1 is ideal Have to ppyosition yourself so that the GPS receiver is in direct line With a satellite sending down the Differential corrections- next time Orbits: ISS- International Space Station GPS- Global Positioning Systems Geosynchronous satellites Earth Revolutions around Earth each day (35,790 km) 8 Orbits http://asd-www.larc.nasa.gov/SCOOL/orbits.html What is our lat and long? http://www.lyngsat.com/tracker/g15.html httppyg://www.lyngsat.com/tracker/anikf1r.htm To find elev and azimuth Of Geostationary satellite: 9 WAAS Differential Correction: http://www.usglobalsat.com/t-what_is_waas.aspx 10 Consequence: Software has to integrate and manage these tools and support science as we practice it as a creative process without interfering with workflow The product , a geological map and data base , is a complex scientific record created incrementally & interactively Mapping is not: A sequence of discrete point measurements Mapping is a continuum of activities requiring one to keep oriented, located, and continually aware of their stratigraphic, lithologic and structural environment. A digital mapping system must support this continuum and implement the routine that mappers deem convenient and essential to natural workflow 11 The visual user interface constitutes the entirety of the link between the geologist and the digital tools The link must be familiar, logical, scientifically functional, comprehensive and easy to personalize for each new area Two main alternative digital mapping systems: Full PC pen tablets running Windows getting faster, smaller and less expensive best for “data fusion” Palm units running Windows CE (data collectors) GeoMapper by Brimhall, Vanegas and Lerch (UCB) Built around the workflow activities of the scientist in the field using the visual user interface as sole control. Vilisual user interf ace h as sci iififilientific functionality providing: Definition of mapping project areas with legends Point and Click- no programming required of user Logical and self explanatory workflow mapping system without menus nor gaps that stop users None of the file transfer of palm CE units 12 GeoMapper Project Manager lets the user define the local stratigraphic column GeoMapper Legend Maker Takes < 1 hour using only point and click A hard copy of the legend can be printed Removes s serious barrier to independent digital mapping User-selected color infill Selectable pre-programmed lithology patterns patterns (Compton, 1985) 13 Button Tool bars Tool bars are arrays of buttons which can be touched by the pen stylus to bring up groups of buttons organized in a logical fashion but providing flex ibility i n sequence Saves screen space for the map and improves speed Lithology structure Formations Mineralization, alteration and sampling sites GeoMapper Color-coded frequency of use hierarchy stop light & left to right Go ahead: Open map, legend, map, sample, export Caution: Undo, erase, redraw, zoom, lost Stop- pay attention: Save, Exit Base maps, ortho-photos, GPS, laser Copyright UC Regents 1999 Mapping workflow continuum Go ahead Tool bars Samples 14 Button Tool bars bring up groups of buttons organized in a logical fashion but providing flexibility in sequence Lithology Formations Structure Mineralization Alteration Mapping on a Vector Topographic Map Outcrop lithology mapping preserves the prime data Colored formation show regional distribution 15 GPS- A Legacy of the Cold war Satellite navigation system using triangulation from 27 satellites orbiting 11,000 miles above the earth Funded and controlled by the Department of Defense (DOD) Coded satellite signals that can be processed in a ground receiver to compute position, velocity and time Method of Ranging Distance = Velocity * Time Velocity = speed of light (3x10exp 10 cm/sec) Time is the unknown Travel times are used to compute distance and are very short 0.06 secs Syy()nchronized to Universal Coordinated Time (UTC): Greenwich Mean Time plus a few seconds (suburb of London on the Thames River , Long. = 0 arbitrarily Accurate atomic clocks on each satellite 16 ISS Moon GPS Geosynchronous 16 2 1 1/30 revolutions around the Earth per day Mean diameter of Earth 12,756 km GPS satellites 20,000 km orbit circle Earth 2 times per day International Space Station in Low Earth Orbit 361-437 km above Earth (15-16 Earth orbits per day) Geosynchronous Earth orbit 35,786 km (5.5 Earth diameters) Mean diameter of Moon 3,476 km (30 days to make one Earth revolution) Mean distance Earth to Moon 384,400 km (30 times Earth's diameter) Operational Modes Now with noise turned off, autonomous GPS accuracy is about +/-5-10 m (15-30 feet) Atmospheric conditions in ionosphere and multi -pathing cause another error by bouncing off other objects before arriving at the receiver Differential Corrections Software algg()orithms called Virtual Base Stations (VBS) Calculate differential corrections that a base station would generate if it were at the receiver location 17 Mathematical requirements x, y, z, time are 4 unknowns Need 4 independent equations At least 4 satellites are needed to get a 3 dimensional location of x, y and z The more satellites the better Our GPS units required at least 4 satellites with a signal to noise ratio about 32 Satellites Visible 18 Types of base (back) maps • No base map. PenMap automatically uses Universal Transverse Mercator (UTM) in meter units. No map prep required • Raster (scanned) bit map image (*BMP) file of a topographic map, ortho-rectified air photo, satellite image. QliffQuality suffers w hen map is enlarged • Vector map of topography made from scanned map or stereo air photos in 2- D or 3-D Digital Elevation model (DEM) • •DiBothgggp()ital raster raster andgrap vectorhics (DRGsimultaneousl) y – eg. An ortho-photo and a topographic map in digital (vector) •ESRIform, Shapefile or a geophysical map all 4 types at once or any combination Topography, orthophoto, geophysics, magnetics, gravity), geography ... Mapping on a Vector Topo Map Outcrops 19 Advantages of Ortho-Images • Since they are ortho-rectified … • They serve as accurate background maps which preserve position,