Survey Manual Chapter 4 Aerial Surveys Colorado Department of Transportation December 30, 2015 TABLE OF CONTENTS Chapter 4 – Aerial Surveys 4.1 General ............................................................................................................................................. 4 4.1.1 Acronyms found in this Chapter ................................................................................................ 4 4.1.2 Purpose of this Chapter .............................................................................................................. 5 4.1.3 Aerial Surveys ............................................................................................................................ 5 4.1.4 Aerial Photogrammetry .............................................................................................................. 5 4.1.5 Photogrammetric Advantages / Disadvantages .......................................................................... 6 4.1.6 Aerial LiDAR ............................................................................................................................. 6 4.1.7 LiDAR Advantages / Disadvantages .......................................................................................... 7 4.1.8 Pre-survey Conference – Aerial Survey ..................................................................................... 9 4.2 Ground Control for Aerial Surveys ............................................................................................ 10 4.2.1 General ..................................................................................................................................... 10 4.2.2 Ground Control Targeting Requirements ................................................................................. 10 4.2.3 Photogrammetry ....................................................................................................................... 11 4.2.4 Aerial LiDAR ........................................................................................................................... 12 4.2.5 Equipment Checking and Calibration ...................................................................................... 12 4.2.6 Permission to Enter Property Form 730a ................................................................................. 12 4.2.7 Underground Utility Locates Prior to Installing Photo Control Monumentation .................... 13 4.2.8 Aerial Ground Control Monumentation ................................................................................... 13 4.2.9 Center Point Control ................................................................................................................. 13 4.2.10 Wing Point Control .................................................................................................................. 14 4.2.11 Aerial Control Targets (Paneling) ............................................................................................ 14 4.2.11.1 Photogrammetry ............................................................................................................................................ 14 4.2.11.2 LiDAR ........................................................................................................................................................... 15 4.2.12 Aerial Control Target Design & Material ................................................................................ 15 4.2.13 Removal of Aerial Control Target Material ............................................................................. 16 4.3 Aerial Control Horizontal Survey ............................................................................................... 17 4.3.1 Aerial Control Horizontal Survey Datum ................................................................................ 17 4.3.2 Minimum Aerial Control Horizontal Survey Accuracy Tolerance .......................................... 17 4.3.3 GPS Photo Control Horizontal Survey Methods...................................................................... 17 4.3.4 Conventional Aerial Control Horizontal Survey Methods ....................................................... 18 4.4 Aerial Control Vertical Survey .................................................................................................... 19 4.4.1 Photo Control Vertical Survey Datum (NAVD 88) ................................................................. 19 4.4.2 Minimum Aerial Control Vertical Accuracy Tolerance .......................................................... 19 4.4.3 GPS Aerial Control Vertical Survey Methods ......................................................................... 19 4.4.4 Conventional Aerial Control Vertical Survey Methods ........................................................... 19 4.5 Aerial Control Survey Report ...................................................................................................... 20 4.5.1 General ..................................................................................................................................... 20 4.5.2 Aerial Control Survey Report .................................................................................................. 20 4.6 Aerial Topo Mapping Standards ................................................................................................. 22 4.6.1 CDOT CADD Standards .......................................................................................................... 22 4.6.2 MicroStation/InRoads Configurations for Consultants ............................................................ 22 4.6.3 MicroStation Level Structure ................................................................................................... 22 4.6.4 Aerial Survey – Photogrammetric Feature Identification ........................................................ 22 CDOT Survey Manual 2 December 30, 2015 4.6.5 Post Aerial or Pre-Aerial TMOSS Supplemental Surveys ....................................................... 22 4.6.6 Minimum Horizontal and Vertical Accuracy Tolerance for TMOSS Supplemental Survey .. 23 4.7 Aerial Mapping Tolerances .......................................................................................................... 24 4.7.1 Aerial Mapping Horizontal Accuracy Tolerance ..................................................................... 24 4.7.1.1 Orthophotography .............................................................................................................................................. 24 4.7.2 Aerial Mapping Vertical Accuracy Tolerance ......................................................................... 25 4.7.3 Existing Constructed Transportation Corridor Template ......................................................... 25 4.7.4 Obscured Areas ......................................................................................................................... 25 Vertical Accuracy Testing - ...................................................................................................... 25 4.7.5 Method of Verifying Accuracy Tolerance ................................................................................ 25 4.7.5.1 Photogrammetry ................................................................................................................................................ 25 4.7.5.2 Aerial LiDAR .................................................................................................................................................... 26 4.8 Aerial Surveys and Photogrammetry Specifications ................................................................. 27 4.8.1 General ..................................................................................................................................... 27 4.8.2 American Society for Photogrammetry & Remote Sensing (ASPRS) .................................... 27 4.8.3 Project Location and Limits ..................................................................................................... 27 4.8.4 Aerial Survey Field Conditions ................................................................................................ 28 4.8.5 Flight Plan ................................................................................................................................ 28 4.8.6 Aircraft ..................................................................................................................................... 29 4.8.7 Aerial Data Acquisition ............................................................................................................ 29 4.8.8 Raw Data .................................................................................................................................. 29 4.8.8.1 Imagery Quality ................................................................................................................................................. 29 4.8.8.2 Film Labeling ..................................................................................................................................................... 30 4.8.8.3 Aerial Triangulation ........................................................................................................................................... 30 4.8.8.4 Digital Image Naming Convention .................................................................................................................... 31 4.8.8.5 Aerial LiDAR - General ...................................................................................................................................