2018 Miami-Dade ITD Lidar DEM: Miami-Dade County, FL

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Information on the NOAA Office for Coastal Management (OCM)

The Data Access Viewer (DAV) allows a user to search for and download elevation, imagery, and land cover data for the coastal U.S. and its territories. The data, hosted by the NOAA Office for Coastal Management, can be customized and requested for free download through a checkout interface. An email provides a link to the customized data, while the original data set is available through a link within the viewer.

The data set footprint in kmz format.

Link to the data set report.

Link to the data set hydro breaklines.

Link to custom download, from the Data Access Viewer (DAV), the lidar point data from which these raster Digital Elevation Model (DEM) data were created.

GPI Geospatial Inc.

The project was divided in two phases: Collection and classification of LiDAR data and creation of 5-foot cell spaced hydro enforced mosaic DEM of the project area.

The LiDAR data was collected utilizing a Riegl VQ-1560i in a Cessna 206 from an approximate altitude of 4,200 feet above ground level, at an approximate ground speed of 110 knots at a pulse rate repetition of 2000 kHg, resulting in an average of 15.2 points per square meter single swath and 20 plus with the 55% overlap. To get under the cloud celling some flight lines were collected at 2,000 feet agl at 110 knots. These lines were collected at 29.12 points per square meter single swath. The sensor used a 60-degree field of view. The project was flown to have 55 percent overlap between swaths. The Global Positioning System (GPS) data were processed using Applanix POSPac Mapping Suite version 8.3 using Smart Base method and single base methods. A fixed bias carrier phase solution was computed in forward and reverse directions. The LiDAR collection took place when Positional Dilution of Precision (PDOP) was at or below 3. Occasionally, the PDOP rose slightly above 3. This had no effect on the data. The GPS trajectory was combined with the IMU data using the Applanix POSPac software. The resulting Smoothed Best Estimate of Trajectory (SBET) was exported and used in Riegl RiProcess software to compute the laser mass point positions in Northing, Easting, and Elevations coordinates. The raw laser data were merged with the SBET using Riegl RiProcess software. The data set was processed using RiProcess, RiAnalyze, and RiWorld software where each flight line was processed to a point cloud. The data was adjusted flight line to flight line using Riegl’s Scan Data Adjustment tool to ensure a proper relative calibration match between flight lines. Each flight was checked for project coverage, data gaps between overlapping flight lines, point density and then exported in LAS 1.4 format. The entire project was collected without gaps.

The LAS files were projected to the NAD_1983_2011_StatePlane_Florida_East_FIPS_0901_Feet and North American Vertical Datum of 1988 (NAVD88). Ellipsoidal heights were converted to orthometric heights using the current Geiod12B. The LAS files were imported to TerraSolid, LTD TerraScan software to be classified to bare earth ground and later feature coded to USGS specifications. The LAS files contain 12 classifications: 1 = unclassified; 2 = ground; 3 = low veg; 4 = med veg; 5 = high veg; 6 = building; 7 = noise points; 9 = water; 10 = buffered ground points surrounding breaklines; 12 = overlap; 17 = overpass and bridges; 18 = high noise. The LiDAR data was run through an automated ground and building classification using terrascan software. A manual check of the building classification was done. The vegetation heights were assigned by an automated process after the bare-earth and buildings were classified. No manual classification of the vegetation class was performed on this data set.

Breaklines were digitized from the LiDAR data in Microstation and elevations were assigned using LP360 and ArcGIS. The double line linear hydrographic features were hydro-enforced with downhill constraints to model correct flow patterns. Water bodies were hydro-flattened to ensure uniform elevation across the feature.

DEMs were created using QCoherent LP360 software. The bare-earth LAS data was loaded into the software along with the tile layout and hydro shapefile collected from the LAS data set. DEMS were produced at a 5ft cell size and hydro-flattened. To QC the DEMs, Global Mapper was used to check for completeness of the tiles and that the hydro features were flattened and represented correct elevations. Once the QC was complete the files were exported out of ArcGIS to create Arc DEM.

COLLECTION DATES: 4/25/18, 4/26/18, 4/29/18, 4/30/18, 5/01/18, 6/05/18, 6/06/18, 6/22/18, 12/05/18

173 flight lines of data were collected.

The NOAA Office for Coastal Management (OCM) received 1file in esri ArcGrid format from the Miami-Dade County Information Technology Department (ITD). The bare earth raster file was at a 5 ft grid spacing. The data were in FL State Plane, Zone 0901, NAD83(2011), US survey foot coordinates and NAVD88 (GEOID12B) elevations in feet. OCM converted the file from esri ArcGrid format to Geotiff format and the file was assigned the EPSG codes of 6438 (horizontal) and 8228 (vertical) and then copied to https for Digital Coast storage and provisioning purposes using an internal OCM script.