Description: <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN>Planimetric Building Footprint features. In 2006, the Des Moines Regional GIS group contracted with Sanborn to digitize the planimetric features utilizing 3D stereo digitizing methods and GIS processing required under the RFP. The Program Management task included coordination and oversight of the NewCom Technology tasks; incorporating the imagery and photogrammetric data from the spring of 2006 flight, stereo digitizing the planimetric features and GIS processing of the impervious surface features to ensure clean topological data structure for subsequent area / polygon calculations. Maintainenance of the data includes heads-up digitizing using the orthophoto images.</SPAN></P><P><SPAN>Building Height and Base Elevation calcuated from Iowa Lidar.</SPAN></P><OL><LI><P><SPAN>Downloaded Iowa Lidar for the Des Moines area from GeoTree (</SPAN><A href="http://geotree2.geog.uni.edu/Lidar/iowa_lidar_metadata.html"><SPAN>http://geotree2.geog.uni.edu/Lidar/iowa_lidar_metadata.html</SPAN></A><SPAN>). Units of measure in meters.</SPAN></P></LI><LI><P><SPAN>Created a LAS Dataset using ESRI tools (</SPAN><A href="http://resources.arcgis.com/en/help/main/10.2/index.html"><SPAN>http://resources.arcgis.com/en/help/main/10.2/index.html#//015w0000004q000000</SPAN></A><SPAN>)</SPAN></P></LI><LI><P><SPAN>Used ArcMap to create layer files for Buildings and Bare Earth from the LAS Dataset.</SPAN></P></LI><LI><P><SPAN>Created raster files for Buildings (Unassigned filter values) and Bare Earth (Ground filter values) using LAS Dataset to Raster.</SPAN></P></LI><LI><P><SPAN>Created Random points for buildings using PLMBuildingFootprints as the Constraining Features for the Building Elevations with 100 points per feature with a minimum allowable distance of 1. (</SPAN><A href="http://resources.arcgis.com/en/help/main/10.2/index.html"><SPAN>http://resources.arcgis.com/en/help/main/10.2/index.html#/Obtaining_elevation_information_for_building_footprints/00q80000007n000000/</SPAN></A><SPAN>)</SPAN></P></LI><LI><P><SPAN>Used Add Surface Information tool and added the elevation information to the building points from the building elevation raster layer.</SPAN></P></LI><LI><P><SPAN>Used Summary Statistics tool and, based on the Fire Marshal’s advice, selected Maximum for the Statistic Type with CID as the Case field.</SPAN></P></LI><LI><P><SPAN>Buffered the PLMBuildingFootprints layer by 1 meter.</SPAN></P></LI><LI><P><SPAN>Created Random points for the buffered areas using the buffered areas as the Constraining Features for the Bare Earth Elevations with 100 points per feature with a minimum allowable distance of 1.</SPAN></P></LI><LI><P><SPAN>Used Add Surface Information tool and added the elevation information to the buffered area points from the Bare Earth raster layer.</SPAN></P></LI><LI><P><SPAN>Used Summary Statistics tool and selected Minimum for the Statistic Type with CID as the Case field.</SPAN></P></LI><LI><P><SPAN>Joined the buffered area summary information back to the buffered polygon feature class using CID to ObjectID.</SPAN></P></LI><LI><P><SPAN>Calculated the BaseElevFt field with MIN_Z field and then removed the join.</SPAN></P></LI><LI><P><SPAN>Joined the buffered polygon feature class to PLMBuildingFootprints using Org_ID field to ObjectID.</SPAN></P></LI><LI><P><SPAN>Selected all records where the buffered polygon feature class BaseElevFt field was not Null.</SPAN></P></LI><LI><P><SPAN>Calculated the PLMBuildingFootprints BaseElevFt field with the buffered polygon feature class BaseElevFt field and then removed the join.</SPAN></P></LI><LI><P><SPAN>Joined building summary information back to the PLMBuildingFootprints using CID to ObjectID.</SPAN></P></LI><LI><P><SPAN>Selected all records where the MAX_Z fields was not Null.</SPAN></P></LI><LI><P><SPAN>Calculated the BuildingHeightFt field by subtracting the MAX_Z field from the BaseElevFt field and removed the join.</SPAN></P></LI><LI><P><SPAN>Multiplied BuildingHeightFt and BaseElevFt fields by 3.28084 to convert the values from meters to feet.</SPAN></P></LI><LI><P><SPAN>For Building Footprints within Residential or Agricultural parcels, the building elevation values were resummarized using the Mean elevation value instead of Maximum as stated in step 7.</SPAN></P></LI><LI><P><SPAN>Compared values against Control Points and Benchmarks maintained by Des Moines Survey staff and to the Polk County Pictometry data.</SPAN></P></LI></OL></DIV></DIV></DIV>
Service Item Id: 854912e923074161a86c2dc50a254ebe
Copyright Text: Des Moines Area Regional GIS Partnership