High Density Area Boundary Delineation John Hathaway, John Wilson, and Brent Pulsipher (PNNL) Sean A. McKenna and Barry Roberts (SNL) 2008 Partners in Environmental Technology Technical Symposium & Workshop
Delineating the boundary After identifying the high density regions within the surveyed area, how do we create a boundary? We want boundaries that are reproducible, exclude relatively small regions while including the other regions, and separate unique high density regions for summary information, Until now we have used Hand drawn the boundaries from the data on the map (flags or kriged) Technical delineation routines within ArcGIS. 2
Outline The final results (big picture first then the details) Method for creating boundary delineation Difference between delineation for flagged data and kriged data How to pick delineation parameters Analyzing results from delineated areas Modifying delineated regions Iterative approach to final boundary selection Modifying output (changing map display, plot layout, and exporting to GIS) Future Improvements 3
Final Delineated Boundaries & Results The boundaries are drawn around the flagged areas using the kriged data. Summary information is provided about each delineated region. 4
Method for creating the boundary lines 1 2 3 4 5 5 1. VSP select those cells from the kriged density estimates that are larger than the user selected threshold ( clustered cells ). a) Each group of clustered cells is identified within the surveyed area. This identifies how many total regions there are to delineate. 2. The clustered cells for a specific region (that are above the threshold) are identified. 3. A rough boundary line is drawn on each cell boundary between a clustered cell and a blank cell 4. The rough boundary is smoothed. 5. The final delineated boundary is created and displayed.
Method for creating the boundary lines: Flag Data 1 2 3 4 5 1a 1b 2 3 4 5 6 Similar to kriging delineation Change the first steps but repeat the last three kriging steps 1. Take the marker locations (Flags) on the map (1a) and include a user specified square around each marker (1b). a) Each group of clustered squares is identified within the surveyed area. This identifies how many total regions there are to delineate. 2. The clustered squares for a each specific region are identified 3-5. Repeat the steps as described in the previous slide.
Delineation Parameter Selection Minimum size of target area The smallest area of interest (often related to the target area size which drove the transect design) Block size around marker (Flag) Used to delineate the flagged regions (select a block size which is larger than the transect spacing) Minimum kriged value (Density map) The threshold which is used to identify contiguous areas and mark the boundary of each (often similar the the selected flag critical density) 7
Analyzing Results from Delineated Areas: Data Summaries Name and Color identify each area and can be changed by the user. Creation parameters identify how each area was created. Target marker parameters Kriged parameters Manual Detailed summaries of the estimates and data within each delineated area. 8
Analyzing Results from Delineated Areas: Plot Summaries 9 User can select standard colored histograms or box-plots. Can show Box-plots provide a five number summary. - 25 th and 75 th percentiles of the data are the bottom and top line of the box. - Median of the data is the solid line within the box. - The end of each whisker is the smallest of the min/max value or 1.5 multiplied by the distance between the 25 th or 75 th percentile. - The dots identify extreme observations - Squares identify observed points when there are to few to make a box-plot. background values compared to each delineated area. background values compared to all the delineated areas as one. Select which areas to display and the order in which they are displayed. Show plots for individual delineated areas.
Modifying Delineated Areas Delete An individual selected area can be removed from the map and the summary table. Define New After clicking the user can manually draw a delineated area on the map Edit Shape Merge Once clicked the user can change the boundary of a previously defined area After moving the boundary points must press Stop Edit. Creation Parameters change to manual After editing delineated areas to to have overlapping boundaries the merge button can be pressed to join these areas. Delete All Removes all delineated areas on the map. 10
Iterative Analysis Minimum kriged value of 100 ApA Minimum target area size of 20 Acres 65/20 Minimum kriged value of 65 ApA Minimum target area size of 20 Acres 65/40 Minimum kriged value of 65 ApA Minimum target area size of 40 Acres 11
Exporting Output 12 Export the Target Area boundaries to a GIS system. Copy Picture & File Data for the displayed plot Additional data column which gives an identification for each delineated area.
Future Improvements Create Help files for delineation tools Automated Reports for kriged delineation Automated Reports for target marker ( flag ) delineation??? 13