Presentation on theme: "Bringing Historic Maps into GIS Patrick Florance Digital Cartographer Harvard Map Collection Harvard University."— Presentation transcript:
Bringing Historic Maps into GIS Patrick Florance Digital Cartographer Harvard Map Collection Harvard University
Purpose Demonstrate how historical maps can be used within a GIS. Illustrate the techniques used to bring historical maps into GIS Show types of maps that are useful to bring into GIS Convey research conducted at the Harvard Map Collection
GIS A geographic information system (GIS) is a configuration of computer hardware, software, and personnel specifically designed for the acquisition, maintenance, and use of geographically referenced data. Modification of Dana Tomlin’s definition Geographic Information Systems and Cartographic Modeling (1990)
Why bring historic maps into GIS? Use historic maps within GIS as a tool for understanding the spatial relationships of past phenomena –Deforestation –Shoreline change –Socio-economic characteristics of a state or a neighborhood –Place-names –Railroads and transportation networks –Disease
Why bring historic maps into GIS? Context: What exists within one’s study area at a given point(s) in time? –Overlay modern GIS data over historic maps –Early 20th century USGS topographic map of central Mass.
Why bring historic maps into GIS? Context: What exists within one’s study area at a given point(s) in time? –Overlay modern GIS data over historic maps –Early 20th century USGS topographic map of central Mass. –Overlay modern Quabbin Reservoir in semi-transparent blue
Why bring historic maps into GIS? Context: What exists within one’s study area at a given point(s) in time? Close up of northern Quabbin over early USGS topographic map. Features flooded: Towns, roads, railroads, etc.
Why bring historic maps into GIS? Feature Extraction (heads-up digitizing) and encoding –Vectorize: discrete data made up of ordered lists of points and represented by points, lines, and polygons –Trace features and encode those graphics with information – Surface of the earth Anthropogenic features Places, place-names, roads, railways, trails, buildings, bridges, etc. Natural features Rivers, lakes, shoreline, elevation, etc. Abstract/Administrative geography Country, state/province, municipal, parcel/property boundaries, census tracts, etc.
Why bring historic maps into GIS? Feature Extraction (vectorization) –1898 USGS topographic map of Portland, Maine
Why bring historic maps into GIS? Feature Extraction (vectorization) –1898 USGS topographic map of Portland, Maine –Built area extracted (vectorized) in red. –Perhaps trace roads, railroads, shoreline, contours, etc. –Note edge.
Why bring historic maps into GIS? Resource/Research Management Tool –More and more researchers using spreadsheets to manage their research to collect information about places and source material –Think of GIS as sort of a spatial spreadsheet or database, which can be used to join that information to spatial representations
Why bring historic maps into GIS? Analysis –Simple Finding inns that are located within 5 miles of towns with a population over 10,000 in southern France around –More complex Archaeological predictive modeling Spatial analysis techniques to model fire density or disease patterns
Why bring historic maps into GIS? Analysis Interpolated fire density of Constantinople, 1660.
Why bring historic maps into GIS? Graphic presentations or visualization –Make maps, charts, graphs, etc. –Very powerful and useful –See David Rumsey ExampleDavid Rumsey Example
Historic Map as a GIS Data Source Historic maps are made for communicating, not for serving as a basemap/source data for a modern GIS. Positional accuracy: features often moved slightly for clarity (i.e., clustered places, roads along rivers, etc.) Scale distortion Edge-matching Insets Paper streets 1890 map vs map
Data Conversion/Development Process Convert maps to digital form Georeference the digital maps: assign them meaningful spatial coordinates Feature extraction and data modeling ($$) –Generally around 80% of project cost –Heavy overhead before one gets results, which is one of reasons why so many GIS fail.
Convert Printed Map to Digital Image Digital Image (Raster) is composed of a grid of pixels 1898 U.S. railroad map
Convert Printed Map to Digital Image Equipment Large-format scanner –Expensive –Scarce Overhead digital photography Be careful using photocopies –Distortion along edges
Convert Printed Map to Digital Image Resolution Resolution can be expressed as the number of pixels per inch (PPI) Different from spatial resolution of remotely sensed imagery, which is a measure of the smallest object that can be resolved by the sensor or the dimension on the ground represented by each pixel (i.e., 30 meters)
Convert Printed Map to Digital Image Resolution (Cont.) Generally between ppi, average ppi Determine resolution that captures the smallest significant feature Use consistent resolution if working with a map series Capture uncompressed as TIFF (Tagged Image File Format) Consider using image compression for working file If map is in grayscale, capture it in grayscale color model –reduce file size If map repository, consider capturing very high quality for archiving & resampling to lower resolution for GIS work
Georeference the Digital Image/Map Georeferencing converts a digital image (raster dataset) from a nonreal-world coordinate system (image space) to a real- world coordinate system such as latitude and longitude. Makes it “line up” with other GIS data. Allows the digital map image to be viewed with other GIS data.
Need to know locations of at least 3 recognizable features Use more than 3 Locations used to create control points Spread out throughout the map Georeferencing Process 1898 U.S. railroad map
Need to know locations of at least 3 recognizable features Use more than 3 Locations used to create control points Spread out throughout the map Link real-world coordinates to the control points Links used to transform the map image to real-world coordinates Georeferencing Process Lat/Long
Georeferencing: Transformation Transformation adjusts the digital map to make it fit in this real-world coordinate system Affine Transformation - most common –Scale –Skew –Rotation –Shift (Translation)
Affine Transformation: Scale Changes the image scale by expanding or reducing
Affine Transformation: Skew X Y Before After
Affine Transformation: Rotation Rotates x and y axes so that the image is correctly oriented X Y After Before
Affine Transformation: Shift (Translation) X and Y origin are shifted X Y After Before
Georeferencing: Transformation Complete Software creates associated files that contain the coordinate information (i.e.,.tfw) Digital map can then integrated with other GIS data 1898 railroad map with modern vector shoreline overlaid
Root Mean Square (RMS) error –Describes the deviation between the control points in the output image and the values calculated by the transformation –A measure of the accuracy of the control points –In general, lower number the better, with 0 being perfect –Record RMS error –Save control points
Georeferencing Techniques for Historic Maps Use existing coordinates or tics Link features on map to features within GIS datasets that have known real-world coordinates. Global Positioning System (GPS)
Use Existing Coordinates or Tics to Reference the Map in Real-World Coordinates Over 134 types of features: towns, municipal boundaries, road types, railways, hydrology, rice fields, pasture land, post offices, churches, castles, inns, etc. Austro-Hungarian Monarchy Topographic Series, Scale: 1:75,000; Date:
Use Existing Coordinates or Tics to Reference the Map in Real-World Coordinates Topographic map misaligned with modern GIS municipal boundaries (red)
Use Existing Coordinates or Tics to Reference the Map in Real-World Coordinates Step 1: map research –Map projection: polyhedric projection (antiquated) –Coordinate system: Bessel 1841 spheroid Spheroid: estimated shape of the earth as a sphere –Prime meridian: Ferro –Metadata is often located on the topographic map itself However, not in this case –Significant role for the historian
Use Existing Coordinates or Tics to Reference the Map in Real-World Coordinates Step 2: Create a point layer –From geographic coordinates of the 4 corners –Based on the historic coordinate system (Bessel 1841) and prime meridian (Ferro)
Use Existing Coordinates or Tics to Reference the Map in Real-World Coordinates Step 3: Project points into the historic map projection –Polyhedric antiquated –Used a polyconic
Use Existing Coordinates or Tics to Reference the Map in Real-World Coordinates Step 4: Link tic marks on the map to the projected corner points.
Use Existing Coordinates or Tics to Reference the Map in Real-World Coordinates Step 5: Transform the map Georeferenced topo with modern GIS municipal boundaries and rivers overlaid
Use Existing Coordinates or Tics to Reference the Map in Real-World Coordinates Close up: modern municipal boundaries (gemeinden) overlaid on topo Disparate datasets never match up perfectly Off by around feet Detail on map: churches, road types, pastures, etc.
Issue: study area falls on edge of a topo sheet
Area Obscured by Overlap
Mosaic: Match Adjoining Map Sheets Image processing software –Adobe Photoshop –ERDAS Imagine –ArcGIS Spatial Analyst Time consuming
Other Useful Maps with Coordinate Systems Topographic series –USGS 1890s – 1950s: 1:62500 –England & Wales: , 1:63,360 –German Karte des Deutschen Reiches: ; 1:100,000 –China Ministry of National Defense Land Survey: ; 1:100,000 –Survey of India: ; 1:253,440. Nautical charts –Shorelines, soundings, etc. World and regional maps –Historic places, national and provincial boundaries, transportation networks, etc. Globes
Georeferencing Techniques for Historic Maps Use existing coordinates or tics Link features on map to features within GIS datasets that have known real-world coordinates Global Positioning System (GPS)
Feature Linking Use control points to link features on the map to features within a GIS dataset that have known real-world coordinates 1797 Street Map of Boston 2001 MassGIS Digital Orthophoto
Feature Linking Steps Acquire GIS reference dataset to link the map to –Should be of equal or slightly better scale Map research –Map projection, coordinate system/datum –Identify additional map sources for reference Establish reference points to use as links –Cultural features such as street intersections, bridges, buildings, landmarks, monuments, etc. –Try to avoid using natural features such as shoreline, rivers, lakes, etc. because they fluctuate greatly –Check dates of features on the map used as links Project GIS data to match the projection of the map
Feature Linking Steps (Cont.) If georeferencing multiple maps, start with the most current map and work backwards in time –Provides more features to link to
Feature Linking Steps (Cont.) 1797 Street Map of Boston 2001 MassGIS Digital Orthophoto Add at least 3 control points spread out throughout the map Transform the map
City-Wide Maps: Boston Useful for tracing the historical development of: –Streets –Districts & wards –Shoreline –Town boundaries –Monuments –Churches –Schools –Significant buildings shoreline change
City-Wide Maps: Cambridge Full View 1865 street map of the City of Cambridge, MA
City-Wide Maps: Cambridge Detail Detail of 1865 street map of the City of Cambridge, MA
City-Wide Maps Georeferenced Georeferenced 1865 map of Cambridge GIS reference data –City of Cambrige GIS street centerline (shown in red)
Integrate Additional GIS Data with Georeferenced Map Georeferenced 1865 map of Cambridge overlaid with 3D buildings
Integrate Additional GIS Data with Georeferenced Map Georeferenced 1865 map of Cambridge overlaid with 3D buildings and modern shoreline of the Charles River
Urban/Fire Insurance Atlases Publishers: Bromley, Beers, Hopkins, Sanborn, Ordnance Survey (OS) Begin around mid 19th century, early 1800s for OS. Scale of 1:5000 or better Wealth of information –Property: boundaries, owners, addresses –Building: footprints, composition, heights, stories, use, roof types –Other info: streets, fire hydrants, etc.
Urban/Fire Insurance Atlases Detail Detail of 1867 Boston Sanborn
Urban/Fire Insurance Atlases Full View Ungeoreferenced 1867 Boston Sanborn Issues –Bound editions make digital conversion difficult –Insets –Mosaicing or edge- matching
Urban/Fire Insurance Atlases Georeferenced Mosaic Full View Georeferenced 1867 Boston Sanborn with inset mosaiced
Urban/Fire Insurance Atlases Georeferenced Mosaic Detail Georeferenced 1867 Boston Sanborn with inset mosaiced
Urban/Fire Insurance Atlases Integration of Modern and Historical Data Georeferenced 1867 Boston Sanborn with modern buildings overlaid in red
Reconstructing the New Orleans Yellow Fever Epidemic of 1878 Reconstructing the New Orleans Yellow Fever Epidemic of 1878 Andrew Curtis & John Anderson, LSU Example of using historic urban atlases and city-wide maps Textual descriptions Automated data conversion Historical geocoding of death residences Spatial Analysis
Other Useful Types of Maps Census Maps –Most common request –Enormous amount of vectorization work –Scarce Minor Civil Divisions, NY, 1930.
Other Useful Types of Maps Aerial Photography –Vertical photography from mid 1930s to present; developed during WWII –Great for context –Distortion/displacement: scale, relief, and tilt –Use building footprints not rooftops, street intersections, etc. for control points Boston 1952 USDA aerial photo over 2001 MassGIS color orthophoto
Other Useful Types of Maps Map to Map Georeferencing –Compare one map to another –Don’t need real-world coordinates Map of Paris, 1832 Map of Paris, 1865
Georeferencing Techniques for Historic Maps Use existing coordinates or tics Link features on map to features within GIS datasets that have known real-world Global Positioning System (GPS)
A system of satellites & receiving devices used to compute positions on the Earth
Global Positioning System (GPS) Collect ground control points for significant features on the map: building corners, street intersections, monuments, site remains, etc. Lat/Long 1815 map of early 16th century waterworks in Istanbul
Global Positioning System (GPS) Useful for georeferencing when one does not have any reference data or coordinates on the map Primarily used for city-scale or larger scale maps, not for maps of very large regions
Georeferencing Techniques and Historic Maps Georeferencing Techniques and Historic Maps for GIS Use existing coordinates or tics Link features on map to features within GIS datasets that have known real-world coordinates Global Positioning System (GPS)
Rubber Sheeting Expression is used many different ways
Rubber Sheeting “The process of transforming an image from one x,y coordinate system to another” –ArcInfo manual –Includes linear (Affine) transformations
Rubber Sheeting Higher order transformations (warping) –2nd order or higher (nonlinear) that transform through curves –Need minimum of 6 control points –Maps of large areas and unknown projection –Aerial photography
Rubber Sheeting Piecewise Transformation –Uses different transformations in different parts of the map –Used when map is badly warped and data matching is essential –Used for edge-matching –Generally use a full transformation first –How does one record this in the metadata? –Sometimes easier with vector data
Rubber Sheeting - What to Do? Start with a first-order (Affine) transformation Research projection of your map Find good control points Understand there is a fuzziness of inaccuracy in all maps and GIS data. Then move on to higher order transformations and then piecewise transformations
Getting Started Source Materials Historic & contemporary maps –Map & government document libraries –Special collections –Archives –Government agencies –Commercial vendors GIS data –Government agencies –Universities –Libraries –Commercial vendors
Getting Started Software Image processing software –Adobe Photoshop, Photoshop Elements GIS software –ArcView, ArcGIS, IDRISI, AutoCAD, etc. Advanced spatial image processing software (optional) –ArcInfo Grid, Spatial Analyst, ERDAS Imagine, etc. Advanced wavelet image compression software (optional) –If want to disseminate georeferenced maps –ECW, MrSID, JPEG2000
Getting Started Hardware Computer with minimum 512 megs RAM For large processing 1-2 gigs of RAM Access large format scanner or overhead digital photography
Getting Started People GIS skills –Usually takes about 1 to 2 weeks to get up to speed
Do you need to bring your historic map into a GIS? Maybe NOT –Making a map of an historical period. –Using the map as reference to encode pre- existing GIS data. –Digitizing tablet to extract/trace features.
General Future of Bringing Historic Maps into GIS History of cartography community needs more research concerning technical aspects (i.e., map projections and coordinate systems), mentioned by David Woodward at ICHC 2003 GIS community needs to develop more historic projections, coordinate systems, and transformations. Development of geo-historical datasets that can be widely used –must include metadata Accuracy assessment Outreach concerning the use and significance of historical materials for GIS
Future of Bringing Historic Maps into GIS at the Harvard Map Collection Harvard Library Digital Initiative –Georeferencing and disseminating maps online through the Harvard Geospatial Library (HGL) as JPEG2000 –Civil War collection –Early Africa –Chinese topos –Historic USGS topos Experimenting with automated raster to vector data conversion Conducting workshops and developing instructional materials concerning GIS and the humanities/social sciences
Useful Internet Sites The Harvard Map Collection –http://www.hcl.harvard.edu/maps/http://www.hcl.harvard.edu/maps/ Harvard Geospatial Library –http://hgl.harvard.eduhttp://hgl.harvard.edu David Rumsey Map Collection –http://www.davidrumsey.com/index.htmlhttp://www.davidrumsey.com/index.html The Boston Atlas –http://www.mapjunction.com/places/Boston_BRAhttp://www.mapjunction.com/places/Boston_BRA