Comparison of surface models derived by manual lidar and softcopy techniques
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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).

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Comparison of surface models derived by manual lidar and softcopy techniques
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)


Comparison of surface models derived by manual lidar and softcopy techniques1
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



Manual lidar and softcopy data sets
Manual, LIDAR, and Softcopy Data Sets Softcopy Techniques

  • 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: 0.07-0.10m RMS


Breaklines and mass points
Breaklines and Mass Points Softcopy Techniques


1 meter dem generated from manual photogrammetry data set
1-Meter DEM Generated Softcopy Techniquesfrom Manual Photogrammetry Data Set


Manual lidar and softcopy data sets1
Manual, LIDAR, and Softcopy Data Sets Softcopy Techniques

  • 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


Manual lidar and softcopy data sets2
Manual, LIDAR, and Softcopy Data Sets Softcopy Techniques

  • 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
Correlation Coefficients from a Single Model Softcopy Techniques

Red = 0.5-0.7

Yellow = 0.7-0.9

Green = > 0.9


Dem by softcopy photogrammetry
DEM by Softcopy Photogrammetry Softcopy Techniques


Manual lidar and softcopy data sets3
Manual, LIDAR, and Softcopy Data Sets Softcopy Techniques

  • 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


Part of the lidar data set
Part of the LIDAR Data Set Softcopy Techniques


Parts of the three data sets
Parts of the Three Data Sets Softcopy Techniques

Sample Comparisons and Results


Comparison methodology
Comparison Methodology Softcopy Techniques


Sample comparisons and results
Sample Comparisons and Results Softcopy Techniques

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


Sample comparisons and results1
Sample Comparisons and Results Softcopy Techniques

Mixed Land Use


Sample comparisons and results2
Sample Comparisons and Results Softcopy Techniques

Drainage Ditch


Softcopy / LIDAR Integration Project Status Softcopy Techniques

Softcopy Extraction w/LIDAR (Initial Comparison)


Softcopy / LIDAR Integration Project Status Softcopy Techniques

Softcopy Extraction w/LIDAR (Initial Comparison)


Softcopy editing tools
Softcopy Editing Tools Softcopy Techniques

  • Automated

    • Slope Filter (Spikes and Holes)

  • Manual (Stereo Viewing)

    • Point-by-Point

    • Polygon Constant Elevation

    • Polygon Planar Fit


Manual editing tool menu
Manual Editing Tool Menu Softcopy Techniques




One of the stereo pairs
One of the Stereo Pairs Softcopy Techniques


Raw softcopy data
Raw Softcopy Data Softcopy Techniques


After slope filter
After Slope Filter Softcopy Techniques


After slope filter1
After Slope Filter Softcopy Techniques


After manual editing
After Manual Editing Softcopy Techniques


After manual editing1
After Manual Editing Softcopy Techniques


Effects of slope filter
Effects of Slope Filter Softcopy Techniques


Conclusions
Conclusions Softcopy Techniques

  • When Differenced with Manually-Derived Data, Softcopy Results (0.2-0.4m RMS) are Slightly Better than LIDAR (0.3-0.5m 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.


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