Watershed Sciences 4930 & 6920 GEOGRAPHIC INFORMATION SYSTEMS

Transcription

1 PROJECTS Watershed Sciences 4930 & 6920 GEOGRAPHIC INFORMATION SYSTEMS WEEK THREE Lecture 5 PROJECT DATA/IDEAS, PROJECTIONS (Cont.) & LAB REVIEW Joe Wheaton GUEST LECTURE HOUSEKEEPING: LAB 01 GRADES This is exactly what I would have expected Remember only way effort is directly awarded is extra credit HOUSEKEEPING: REMINDER HOUSEKEEPING: GREAT MAPS! Mentioned this on first day of class No one complained now is about the time you may want to whine SURGEON GENERAL S WARNING: This class is a ton of work! Continuing may cause headaches, shortness of breath, loss of sleep, and increased stress levels. But you just might learn a lot about GIS too. We ll highlight 1-3 great labs each week 1

2 HOUSEKEEPING: YOUR GIS WEBSITES Check each other s sites out for some great ideas Some very creative stuff HOUSEKEEPING: QUIZ 1 9 Fails 37 Passes (46 of you) Check Blackboard & Make sure you have a pass Good Map / Bad Map HOUSEKEEPING: QUIZ 02 THE PAPER MAP Your friend Doesn t crash like a GIS (unless your downloading it) QUESTIONS ABOUT QUIZ? THERE ARE A LOT OF QUADS IN UTAH 1:24,000 USGS Quad Index HOUSEKEEPING: QUIZ in Cahce County $8.00 each Available for Free at: 2

3 WHERE TO FIND HOUSEKEEPING: QUIZ 02 E: 432,600 N: 4,621,300 Lat: W Long: N STATE PLANE SYSTEM So where are we? PLSS NW ¼ of NW ¼ of Section 35 Township 12 N Range 12 E For more info: 3

4 HOUSEKEEPING: WHAT DO YOU WANT YOUR MAP TO LOOK LIKE? Sketch out a layout for how you want your map to look like on the back of napkin If you don t know how to make it look like that, ask! READING FOR TODAY III. Universal Transverse Mercator Coordinate System CLASSES OF MAP PROJECTIONS Question: To preserve: Equal areas? (i.e. equivalence) True Shape? (i.e. conformality) Standard Line is contact point(s) III. Universal Transverse Mercator Coordinate System STATE PLANE SYSTEMS Used 3 conformal projections to minimize distortion to one part in 10,000: Lambert conformal conic Transverse Mercator Projection Oblique Mercator Projection (for Alaska) Differs from UTM in origin: Easting origin always arbitrary number of feet west of the western boundary of the zone The northing origin not at the equator as in UTM, instead placed arbitrary number of feet south of the state border 4

5 LAMBERT CONFROMAL CONIC III. Universal Transverse Mercator Coordinate System UNIVERSAL TRANSVERS MERCATOR (UTM) Horizontal cylinder whose diameter is less than earth s diameter Intersects twice so that ring is formed. Ring is 6 wide at equator Projection from earth center outward Used in many USGS and British Ordnance Survey maps Minimal distortion and accurate directions within ring UTM KEY: ADJECTIVE IS TRANSVERSE The UTM projection is designed to cover the world, excluding the Arctic and Antarctic regions. To keep scale distortions within acceptable limits, 60 narrow, longitudinal zones of six degrees longitude in width are defined and numbered from 1 to 60. Accurate areas within 15 of intersecting meridian, accurate directions Used in many USGS maps UNITS: Meters 5

6 UTM ZONES WORLDWIDE 120 OF THEM UTM ZONES IN LOWER 48 STATES UTM EACH ZONE HAS ITS OWN CM Each zone has own central meridian. CM always Easting value always 500,000 m; to avoid negative coordinates For positions north of the equator, the equator is given a Northing value of 0m For positions south of the equator, the equator is given a (false) Northing value of 10,000,000 m From: UTM - HOW FAR IS SIX DEGREES? About 600,000 m at equator How far at poles? III. Universal Transverse Mercator Coordinate System 6

7 COORDINATE TRANSFORMATION A.K.A. Registration or Georeferencing Registers layers to a map coordinates system Brings spatial data into an earth-based map coordinate system so that data can OVERLAY in a GIS Commonly used to convert newly digitized data from arbitrary digitizer coordinate system to map coordinates Can also be used to transfer between coordinates systems Transformation is NOT Map Projection (no statistics in later) SHIFT, ROTATE, SCALE, DATUM ADJUST NEED CONTROL POINTS Control points are points that we know both the map projection coordinates and digitizer coordinates for HOW? i.e. geographic space you want to be in) CONTROL POINTS FROM OTHER IMAGE Keys are: that other image is already registered! & Why these points? (e.g. photo or data to be transformed) CONTROL POINTS FROM FIELD DATA Key is you can see feature on layer to be transformed, and you know you collected those control points in the field ERROR & ITTERATIVE FITTING RMSE provides summary of difference between true (measured) and predicted control point coordinates RMSE e 2 1 e 2 2 e _ e n n Where e i are the residual disances between the true E and N coordinates and the E and N coordinates in output data layer: e x t x d 2 y t y d 2 7

8 HIGHER ORDER TRANSFORMATIONS RASTER RESAMPLING IN ArcGIS, TRANSFORMATIONS: III. Universal Transverse Mercator Coordinate System THIS WEEK S LAB READING FOR THURSDAY Lab 3: Reproducing Maps Geologic Map Teach you how to manipulate display properties and symbology to reproduce a map in as close as possible a fashion to the original. Teach you how to extract summary statistics and data from existing data 8