1 Comparison of Surface Models Derived by Manual, LIDAR, and Softcopy Techniques UW-Madison NCRST-I Research Team Frank Scarpace, Alan Vonderohe, Teresa Adams (Investigators) Nick Koncz (Project Manager) Hongwei Zhu, Amar Padmanabhan, Jisang Park (Research Assistants)

2 Comparison of Surface Models Derived by Manual, LIDAR, and Softcopy Techniques Objectives Determine Differences among Results from the Various Techniques Seek Methods for Improving Accuracies by Technology Integration Seek Methods for Reducing Required Editing Time for Raw Softcopy Data

Test Site: Highway Corridor Near Solon, IA

4 Manual, LIDAR, and Softcopy Data Sets Manual Photogrammetry Data Set Provided by Iowa DOT and CTRE: Breaklines and Mass Points (~20-Meter Spacing) Compiled on Analytical Stereoplotters from 1:4800 (nominal scale) photos Expected Accuracy: m RMS

5 Breaklines and Mass Points

6 1-Meter DEM Generated from Manual Photogrammetry Data Set

7 Manual, LIDAR, and Softcopy Data Sets Softcopy Photogrammetry Data Set: Same Photography as Manual Method Same Camera Calibration Same External Orientation Parameters Film Diapositives Scanned at 15 Micrometers 38 Photos in 3 Strips – 35 Stereo Models

8 Manual, LIDAR, and Softcopy Data Sets Softcopy Photogrammetry Data Set: In-House Software Resampled Epipolar Images 1:32 Image Pyramids Cross-Correlation Least Squares Matching Generates Irregular 1-Meter Spacing of Elevations

Correlation Coefficients from a Single Model Red = Yellow = Green = > 0.9

DEM by Softcopy Photogrammetry

11 Manual, LIDAR, and Softcopy Data Sets LIDAR Data Set: Irregular 2-Meter Spacing of Elevations Expected Accuracy: 0.15m RMS Raw Data Were Edited, But Some Vegetation (e.g., Crops) Were Not Removed

12 Part of the LIDAR Data Set

13 Parts of the Three Data Sets Sample Comparisons and Results

Comparison Methodology

Sample Comparisons and Results Preliminary Results Indicate that Softcopy Data are at Least as Good as LIDAR when Compared to Manually- Extracted Data.

16 Sample Comparisons and Results Mixed Land Use

17 Sample Comparisons and Results Drainage Ditch

18 Softcopy / LIDAR Integration Project Status Softcopy Extraction w/LIDAR (Initial Comparison)

19 Softcopy / LIDAR Integration Project Status Softcopy Extraction w/LIDAR (Initial Comparison)

20 Softcopy Editing Tools Automated Slope Filter (Spikes and Holes) Manual (Stereo Viewing) Point-by-Point Polygon Constant Elevation Polygon Planar Fit

21 Manual Editing Tool Menu

22 Manual Editing Polygon Selection Tool

23 Manual Editing Set-to- Constant Elevation Tool

One of the Stereo Pairs

Raw Softcopy Data

After Slope Filter

After Manual Editing

Effects of Slope Filter

31 Conclusions When Differenced with Manually-Derived Data, Softcopy Results ( m RMS) are Slightly Better than LIDAR ( m RMS). When LIDAR is Used as First Approximation for Softcopy, Results are Mixed with Improvements of 20% (to 0.16m RMS) in Some Cases. Slope Filter Improves Raw Softcopy Data by 10%. Comparisons with Manually-Edited Softcopy Remain to be Done.