AAFC – Multiple Sites - Saskatchewan
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AAFC – Multiple Sites - Saskatchewan LiDAR Survey Report March, 2012 TABLE OF CONTENTS 1. SUMMARY……...……………………………………………………………………....1 2. MATRIX LiDAR SYSTEM……………………………………………………….........2 2.1 MATRIX Installation…………………...…………………………………............2 2.2 IMU-GPS Antenna Offset Survey………………………………………………...4 2.3 IMU-Laser Misalignment…………………………………………………………4 3. GPS SURVEY CONTROL…...………………………………………………………....5 3.1 GPS Control Points……………....……………………………………………….5 4. DATA COLLECTION…………………………………………………………………8 5. GROUND CHECKPOINTS……………………….…………………………………. 10 6. DATA PROCESSING……………………………..…………………………….……..13 6.1 LiDAR Point Clouds……………………………………………………….……13 6.1.1 LiDAR Tiles……………………………………………………………….13 6.1.2 Grounds Points……………………………………………………………..13 6.1.3 DTM Key Points…………………………………………………………...14 6.1.4 Vegetation………………………………………………………………….15 6.2 Grid Points……………………………………………………………………….15 6.3 Hillshades……………………………………………………………………...…16 6.4 Orthorectified Imagery…………………………………………………………..16 6.5 LiDAR Contours…………………………………………………………….…..17 APPENDIX A – GPS NETWORKS…………………………………………………..19 APPENDIX B – CONTROL PHOTOS…………………………………………….....23 1. SUMMARY LiDAR Services International (LSI), a Calgary-based LiDAR company completed an airborne LiDAR survey for Agriculture and Agri-Foods Canada (AAFC) in October-November 2011. The Fall 2011 portion of the project involved collection of LiDAR data for the Pheasant Creek, Roughbark, Moosomin, Braddock, Maple Creek, Eastend and Altawan project sites in Southern Saskatchewan. LiDAR data was successfully collected, processed and delivered with the following conditions: LiDAR system installed in a Cessna 185 airplane owned and operated by CanWest Corporate Air Charters of Slave Lake, Alberta Airborne LiDAR collection occurred October 25-November 20th, 2011. LiDAR data was collected at a flying height of 600 m above ground level and an air speed of 240 km/h. Riegl LMS-Q560 laser used pulsed at an approximate rate of 137 kHz resulting in a computed average of ground spacing equal to 0.70 m Horizontal Datum: NAD83 (CSRS) Vertical Datum: CGVD28 orthometric heights (HTv2.0 height transformation model) Map projection: UTM Zone 13 (Central meridian = 105 degrees west longitude) Deliverable included: o 1m bare earth and full feature grids in 1 km x 1 km tiles (ASCII XYZ format) o 1m bare earth and full feature greyscale hillshades for each project area (GeofTiff) o Classified LiDAR point clouds and ASCII extractor program in 1km x1km tiles (LAS v1.2 format) o Orthorectified imagery with 0.2m pixel size in1 km x 1 km tiles (GeoTiff and ECW format) and 1 MrSID image for each project area o LiDAR contours 0.5m intervals (DWG and Shp format) in 1 km x 1 km tiles o LiDAR tile Index (ESRI shp format) o LiDAR survey report 1 2. MATRIX LIDAR SYSTEM 2.1 MATRIX Installation The MATRIX LiDAR system was installed in a Cessna 185 (C-GAYZ) airplane, as shown below in Figure 1, owned and operated by CanWest Corporate Air Charters of Slave Lake, Alberta. Figure 1: Cessna 185 with MATRIX LiDAR system The Riegl LMS-Q560 scanning laser and inertial measurement unit were mounted on a plate extending out of the rear baggage hold, as seen in Figure 2. The system computers and data storage devices were mounted to the floor in the rear of the aircraft, as seen in Figure 3. The GPS antenna was mounted with a clamp on the front of the right wing next to the fuselage and the operator controlled the MATRIX system with a monitor and keyboard from the front passenger seat. Transport Canada has approved the installation of the MATRIX LiDAR system into this survey aircraft. Key sensors utilized in the MATRIX installation for the LiDAR survey included: Riegl LMS-Q560 200 kHz laser scanner and data recorder NovAtel V-3 dual frequency GPS receiver NovAtel SPAN LCI 200 Hz Inertial Measurement Unit (IMU) Canon EOS 1D Mark III, 10 Mega Pixel Digital Camera 2 Figure 2: Laser, Camera and IMU mounted on Cessna 185F Figure 3: Matrix computers and data storage devices 3 2.2 IMU - GPS Antenna Offset Survey Several parameters unique to each aircraft LiDAR installation must be determined in order to produce accurately positioned LiDAR point clouds. These parameters include the three dimensional vector (lever-arm) between the GPS antenna phase center and the inertial body reference. Using a total station and prisms at several points surrounding the aircraft, redundant distances and angles to the IMU unit and GPS antenna were observed. The observations were then subjected to a least- squares adjustment to compute the final lever arm values. As this particular aircraft had been used by LSI for LiDAR surveys many times in the past, the GPS to IMU distance had been previously calculated. A portion of a GPS-IMU offset survey on the aircraft is shown in Figure 4 below. Figure 4: Cessna 185F lever-arm survey 2.3 IMU – Laser Misalignment LiDAR calibration passes were made at the beginning and end of each flight to allow for the determination and verification of the roll, pitch and heading misalignment angles between the IMU measurement axis and the laser sensor. The calibration passes consisted of three to four flight lines flown at orthogonal and parallel headings at the project flying height and speed. Features such as buildings and roads were used to compute and verify the misalignment angles for the project install. 4 3. GPS SURVEY CONTROL 3.1 GPS Control Points High-precision kinematic GPS solutions were obtained for the LIDAR data collection missions using differential GPS (DGPS) survey techniques. DGPS requires a static GPS receiver collecting data at a known ground control point in the vicinity (generally within 35 km) of the airborne (remote) GPS receiver during LiDAR data collection. All of the collected and processed LiDAR and imagery data is referenced to the 3D coordinates of the ground control points. For consistency and accuracy high order, Federal Geodetic Survey Division (GSD) GPS control points were used for referencing of all the project sites. LSI surveyors monumented and increased the density of the existing GSD control networks to allow GPS benchmarks to be within 35km of the project areas and at local utilized airports. To determine the accurate positions of the new GPS benchmarks four GPS survey networks were created; Pheasant Creek, Moosomin, Roughbark and one for the areas surrounding Swift Current including Braddock, Eastend, Maple Creek and Altawan. Figures of the four control point networks can be seen in Appendix A. Below, in Tables 1 and 2 are the control coordinates used for the 2011 AAFC LiDAR survey. Table 1 are the geodetic control coordinates in NAD83 (CSRS) with ellipsoid heights and Table 2 contains the UTM Zone 13 positions with CGVD28 orthometric heights utilizing the HTv2.0 height transformation model. Additionally photos of all of the GPS control points can be seen in Appendix B. 5 Table 1: GPS Control Coordinates NAD83 (CSRS) Monument Ellipsoidal HT2.0 ID Type Latitude Longitude Height (m) Geoid (m) Moosomin 68s273 GSD 50 12 57.94860 -101 48 47.10640 560.03 0 21.677 MoosominGPS LSI spike 50 02 55.71764 -101 40 36.17673 520.544 21.543 VirdenAIR LSI spike 49 52 35.96509 -100 55 08.02237 419.151 22.456 Pheasant Creek 84s275 GSD 50 50 46.3946 -103 49 53.5362 570.04 0 20.481 PCGPS LSI spike 50 44 13.32691 -103 20 00.71256 561.434 20.741 ReginaAIR LSI spike 50 25 55.85721 -104 39 11.67804 555.748 19.597 Roughbark 94v053 GSD 49 40 43.339 -102 58 38.2092 0 604.48 0 19.035 WeyburnAIR LSI spike 49 41 49.63949 -103 48 26.58886 566.354 18.872 WeyGPS LSI spike 49 31 22.10015 -103 44 52.62617 555.544 18.654 SW Sask 80s094 GSD 49 43 37.17512 -108 09 29.59387 854.737 16.531 94v050 GSD 49 59 23.10819 -109 28 05.92757 771.362 17.233 94v051 GSD 50 14 57.87090 -107 46 09.26740 798.870 17.893 A230581 GSD 49 58 39.18304 -110 45 46.26312 706.423 17.143 Admiral LSI spike 49 43 39.86000 -107 54 07.00811 777.775 16.810 Altawan LSI spike 49 13 26.49991 -109 49 03.84398 918.015 15.603 Braddock LSI spike 50 06 22.46381 -107 18 06.31430 744.920 18.142 Cadillac LSI spike 49 46 07.88578 -107 35 08.94909 740.030 17.243 Eastend LSI spike 49 30 34.13721 -108 45 48.76528 896.127 16.016 MapleAIR LSI spike 49 53 49.20037 -109 28 50.21885 750.623 16.926 Medicine Hat LSI spike 50 01 22.50574 -110 43 27.34653 699.783 17.254 Russell LSI spike 49 54 13.19900 -107 30 22.64803 756.087 17.545 Shaunovan LSI spike 49 39 18.09667 -108 24 25.94074 904.853 16.261 USBorder LSI spike 49 00 01.64843 -109 43 57.33403 826.921 15.388 6 Table 2: GPS Control Coordinates UTM Zone 13 CGVD28 ID Easting (m) Northing (m) Elevation (m) Moosomin 68s273 727350.326 5567518.961 581.70 6 MoosominGPS 737905.533 5549349.536 542.087 VirdenAIR 793186.537 5532907.521 441.607 Pheasant Creek 84s275 582260.100 5633374.760 590.520 PCGPS 617591.903 5621907.092 561.434 ReginaAIR 524627.481 5586741.982 575.344 Roughbark 94v053 645921.284 5504872.873 623.515 WeyburnAIR 586005.920 5505638.923 585.226 WeyGPS 590614.525 5486329.411 574.197 SW Sask 80s094 272399.306 5513065.499 871.268 94v050 179757.204 5547064.648 788.594 94v051 302579.154 5570031.036 816.762 A230581 86921.816 5552067.817 723.565 Admiral 290868.468 5512402.603 794.584 Altawan 149262.559 5463539.272 933.618 Braddock 335411.637 5552980.174 763.062 Cadillac 313805.352 5516140.380 757.272 Eastend 227574.018 5490904.144 912.142 MapleAIR 178257.547 5536810.399 767.550 MedicineHat 90073.167 5556894.640 717.036 Russell 320032.520 5530931.881 773.632 Shaunovan 254096.096 5505851.789 921.112 USBorder 153904.113 5438305.786 842.309 For future surveys in the project areas it is important that at least one of the control points listed in the above tables are used for geo-referencing in order to obtain positions in agreement with the LiDAR data collected in 2011.