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Orthorectification and Distortion Analysis of H...

Orthorectification and Distortion Analysis of Historic 1800s San Jacinto Battleground Maps using ERDAS Imagine and an Open Source Tool

Presented by Nancy Heger, Texas Parks & Wildlife (TPWD)

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  1. Orthorectification and Distortion Analysis of Historic 1800s San Jacinto Battleground

    Maps using ERDAS Imagine and an Open Source Tool Nancy A. Heger Texas Parks and Wildlife Department
  2. San Jacinto Battleground ► Site where Texas won its independence ► Currently

    is §  A State Historic site and State Park §  Site of Battleship Texas
  3. San Jacinto Battleground TPWD Staff ►  needed to identify sites

    of archeological significance before doing restoration work ►  Also interested in change through time Purpose ►  Use historic maps of the San Jacinto Battleground to §  identify sites of historical significance §  Document change through time
  4. Methods - 2 Historic Maps Yoakum Map (approx. 1856) § 

    H. Yoakum was a TX Historian; 2 volume History of Texas §  Consulted with Sam Houston about the battle details §  No map scale included §  No evidence that he was a surveyor or cartographer §  Size: 11x19cm or 7.3”x4.6” §  Source: University of North Texas website "Portal to Texas History" at http:// texashistory.unt.edu/ark:/ 67531/metapth2490/ McArdle Map (approx. 1892) §  Artist; Painted the Battle of San Jacinto (1895) §  Extensive battle research; interviewed battle survivors §  Includes map scale §  He served as a mapmaker during the civil war §  Map drawn on back of TX State stationery §  Source: Texas State Library and Archives Commission (TSLAC) at https:// www.tsl.texas.gov/mcardle/ sanjac/sanjac014.html
  5. Methods ►  Digitized map on a flatbed scanner at 600dpi

    to create a TIFF ►  Orthorectified by block triangulation using ERDAS Imagine 2011 Leica Photogrammetry Suite (LPS 2011) ►  Potential Problems §  Little detail on maps = difficult to create control points §  Few historic map points to relate to present day §  Was this even do-able?
  6. Methods ►  Potential Problems §  Few historic map points to

    relate to present day §  Was this even do-able? Answer: Maybe ►  Used additional historic maps and imagery to generate control points §  mosaicked 1995 DOQQ §  1920 ed. orthorectified USGS topographic maps §  1930 orthorectified aerial image (Tobin collection)
  7. Methods – Reference Imagery 1916 (1920 ed.) Topo 1930 Aerial

    1995 DOQQ Timescale 1836 1916 1930 1995 90 yrs 65 yrs Map topo aerial DOQQ 14
  8. Methods 1995 DOQQ (Reference Imagery for all) 1920 Topo 1930

    Aerial Yoakum Map 1995 DOQQ (Reference Imagery for all) 1920 Topo 1930 Aerial McArdle Map Orthorectification Orthorectification Orthorectified Yoakum Map
  9. Initial Orthorectification Products ► McArdle map very problematic; poor fit ► Yoakum

    map better, but not to our group’s usual standards ► Consulted with an archeologist familiar with site §  Provided insight §  Resulted in much improved results
  10. Importance of Archeological Consultation ► Knowledge of historic roads §  movement

    §  Where evidence is sometimes seen in certain seasons ► Knowledge of dredging and soil movement; when it became more frequent ► Where road to fairy was ► Where historic buildings probably were ► The Canon story
  11. Confirmation of Distortion ► Used an open source tool called Map

    Analyst ► Made for archeologists to identify map distortion ► Also provides displacement vectors
  12. Other Potential Uses for Map Analyst ► Distortion analysis of any

    graphically drawn non-GIS map ► Assessment of distortion in orthorectified imagery
  13. Conclusions ► Yoakum map is drawn much more accurately than McArdle

    map ► Yoakum map drawn surprisingly well §  Could be used to identify areas of historical significance and to investigate change through time by TPWD staff ► Used Yoakum map to create an ArcGIS Online application for the public §  to demonstration change in the area from1836 to present.