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~~~r~ ~~~, I~~, <br />~® <br />®. <br />®~ - - .-® <br />N 'I'IS ISSUE <br />® Standards and <br />Qualifications are your <br />"A.C.E. in the Hole" <br />® Upcoming Events <br />Issue 10 #1 <br />JULY <br />1998 <br />Published by: <br />John Anderson <br />EnviroData, ][IiC. <br />5831 Cedar Lake Road <br />Minneapolis <br />Minnesota <br />55416 <br />612/544-1761 <br />Fax: 612/593-9546 <br />E-mail: hydric@aol.com <br />Website: www.expert- <br />market. com/envirodata/ <br />Why should a Local Government Unit, state or federal agency, or private <br />developer be concerned about wetland mapping standards and the <br />professional qualifications of those creating this information? The answer is: <br />Accuracy + Consistency + Effectiveness (A.C.E.). <br />Accuracy <br />In order to improve accuracy, the federal government has developed national <br />mapping standards for spatial accuracy. These standards help to ensure that <br />"Point A" on the map correctly represents the location of "Point A" in the <br />real world. The Federal Geographic Data Committee (FGDC) has adopted <br />the Cowardin (NWI) Wetland. Classification System to help provide greater <br />accuracy in wetland classification. <br />Consistency <br />Specialists from wetland inventory programs have developed systems of <br />quality assurance and control to create more uniformity in wetlands <br />mapping. These systems help to ensure that maps of "Area A" are accurate <br />and consistent with maps of "Area Z". They also enable mappers to <br />"update" maps in a consistent manner. <br />Using effective quality assurance procedures, wetland map-makers codify <br />procedures to account for variables in raw data (i.e. aerial photography, <br />satellite imagery). These variables are caused by weather patterns, variations <br />in vegetation, landuse impacts and localized or regional differences in soils <br />and geomorphology. <br />An important use of quality assurance procedures is to account for <br />differences in photographic emulsions or digital image processing <br />techniques. It is not difficult to imagine that the same wetlands types will <br />look different when seen on color infrared, true color, or black and white <br />aerial photography. However, wetlands may also appear very different even <br />when images are acquired during a single photographic mission. <br />Errors in processing of the photographic emulsion may cause the images to <br />appear "washed out." Errors may also cause images to develop a shade or <br />tone which differs from the signature typical of wetlands within the work <br />area. Similar digital images may be processed differently because the <br />computer "sees" variations in electronic components of an image called <br />pixels (picture elements). Metadata (documentation) are developed to <br />provide a reference source to map-users. They describe procedures and <br />account for variations in raw data. <br />Inconsistency in spatial accuracy and classification may cause map-users to <br />lose confidence in the data. Some inconsistency in development of wetlands <br />data is, of course, unavoidable. Differences in imagery caused by weather <br />patterns, land use changes, image processing, etc., will cause variability in <br />wetland signatures. However, the experienced wetland mapping <br />professional can account for these variabilities and develop a consistently <br />accurate wetlands database. (more on back page) <br />