Accuracy assessment and 3D Mapping by Consumer Grade A presentation at Master Oral Defense. January 10, 2019.

1. Accuracy Assessment and 3D
Mapping by Consumer Grade
Spherical Cameras
Student : 費道斯 / Muhammad Irsyadi Firdaus
Advisor : 饒⾒有 / Prof. Jiann‐Yeou Rau
Laboratory of Cyber City
Department of Geomatics
National Cheng Kung University, Taiwan
1

2. Outline
2
Introduction
Methodology
Analysis and Discussions
Conclusion
Future works
Background
Motivation
Objective
Study Area
Equipment
Data and Workflow
Metric Quality Assessment
Angle Delineations
Ground Sampling Distance (GSD)
Image Orientation

3. Introduction
3
 3D building model reconstruction is an important issue for urban planning,
disaster management, BIM (Building Information Model) generation and cultural
heritage documentation.
 Close‐range photogrammetric method can be used to obtain 3D building model.
 Spherical panoramic images is proposed to create 3D building model.

4. Introduction
4
Frame-based camera
1. Smaller FOV
2. Longer data acquisition time
3. More human effort
Purpose : to reconstruct 3D
indoor/outdoor environment
Spherical camera
1. 720 degrees FOV
2. Shorter data acquisition time
3. Less human effort
Specific Object
Indoor environment
Outdoor environment

5. Introduction
5
Spherical image of an indoor
Stitching Spherical imagery is created by
digitally stitching multiple images taken
from the same position with different
orientations.
21

6. Introduction
6
The relationship between 3D and 2D spherical image coordinate
Where:
x, y, z = Cartesian panoramic coordinates
= Cylindrical coordinates
x′, y′ = metric image coordinates
u, v = pixel coordinates
An image point P′ can be defined either by
the cylindrical coordinates or Cartesian
panoramic coordinates
Spherical panoramic imaging model
‐900
900
00
1800
00
900
2700
00
2700
900
1800
900

7. 7
Methodology
Outdoor Environment
Indoor Environment
Study Area
Study Area and Material

8. 8
Methodology
Device GARMIN VIRB 360 Samsung Gear 360
Sensor type CMOS CMOS
Number of
camera
Two Two
Image size 3840 x 2178 2560 x 1280
Image Format
Stitched image from spherical
cameras in equal-rectangular
projection
Stitched image from
spherical cameras in
equal-rectangular
projection
Software
Spherical Camera
Software and Hardware

9. 9
Methodology
Device Garmin Samsung
Location Indoor Outdoor Indoor Outdoor
No. of photos taken 497 262 719 565
Object distance(unit: m) 3.69 6.24 2.89 7.52
Area (unit: m2) 176 941 105 1600
GSD (unit: cm/pix) 0.6 0.7 0.71 1.9
Summary of the achieved datasets
Tachymetric network for surveying the
reference points
Data Acquisition

10. 10
Methodology (Outdoor)
location of reference points location of reference line
Reference points/lines surveying

11. 11
Methodology (Indoor)
location of reference line location of reference points
Reference points/lines surveying

12. Methodology
12
Reference Lines and
Reference Points
Spherical Panorama
Images
Camera self-calibration
Marking reference line
and reference Points
Aerial Triangulation
Referencing accuracy
analysis
Dense image matching
Point cloud refinement
Export point cloud to
*.las file format
Point cloud
digitization
Convert point cloud
to *.pcg
Angle delineation
analysis
Building CAD model
from point cloud
Photoscan
Revit
Workflow

13. Methodology
13
Aerial Triangulation in indoor building
• 719 images are acquired
• All Images taken by Samsung Gear 360
• 497 images are acquired
• All Images taken by Garmin VIRB 360

14. Methodology
14
Aerial Triangulation in outdoor building
• 565 images are acquired
• All Images taken by Samsung Gear 360
• 262 images are acquired
• All Images taken by Garmin VIRB 360

15. Methodology
15
Distribution of reference lines/points in indoor building
Reference Lines Reference Points
• 14 reference lines
• 29 reference points

16. Methodology
16
Distribution of reference lines/points in outdoor building
Reference Lines Reference Points
• 21 reference lines
• 163 reference points

17. Methodology
17
3D texture model of spherical panoramic image using (a) GARMIN
VIRB 360 and (b) Samsung Gear 360
3D texture model in indoor building
• In indoor, Samsung
Gear 360 has a
smoother texture than
Garmin VIRB 360

18. Methodology
18
3D texture model of spherical panoramic image using (a)
GARMIN VIRB 360 and (b) Samsung Gear 360
3D texture model in outdoor building
• In outdoor, Garmin VIRB 360 has a
smoother texture than Samsung
Gear 360

19. Methodology
19
Corner angle delineation in outdoor
• There are 18 corners that
are measured
• Each corner is 90-degree
angles as an angle of the
field

20. Methodology
20
• There are 6 corners that are
measured
• There is a difference between the
angle of the field and the angle of the
measurement
Corner angle delineation in indoor

21. Methodology
21
a
b
3D CAD model from point cloud, (a) viewed
from the top and (b) viewed from the front
Point cloud digitization in outdoor building
• A 3D building CAD model was created manually
using point cloud generated by Garmin VIRB 360.

22. Methodology
22
3D CAD model from point cloud, (a) viewed
from the back and (b) viewed from the top
Point cloud digitization in outdoor building
• A 3D building CAD model was
created manually using point
cloud generated by Garmin
VIRB 360.

23. Analysis and Discussions
23
Reference scale line in the image
Errors (unit: cm)
GARMIN VIRB 360 Samsung Gear 360
No. of Control Line = 7 4.89 15.32
No. of Check Line = 14 14.49 30.38
Reprojection (unit: pixels) 1.49 1.08
RMSE of horizontal
errors (cm)
RMSE of vertical
errors (cm)
Re-projection errors
(pix)
Garmin
VIRB 360
Samsung
Gear 360
Garmin
VIRB 360
Samsung
Gear 360
Garmin
VIRB 360
Samsung
Gear 360
No. of Control
Points = 23 54.3 130.7 10.2 38.2 1.52 4.55
No. of Check
Points = 140
49.5 124.9 19 29.4 5.66 6.28
Metric quality assessment in outdoor
Comparisons of reference points
Comparisons of reference line
• Garmin VIRB 360 is better than
Samsung Gear 360
• For comparisons of reference,
reference line are better than
reference points

24. Analysis and Discussions
24
Metric quality assessment in indoor
Reference scale line in the image (unit: cm)
Errors
GARMIN VIRB 360 Samsung Gear 360
No. of Control Line = 4 6.76 4.97
No. of Check Line = 10 8.3 7.8
Re-projection (unit: pixels) 4.64 2.47
RMSE of horizontal
errors (cm)
RMSE of vertical
errors (cm)
Re-projection errors
(pix)
Garmin
VIRB 360
Samsung
Gear 360
Garmin
VIRB 360
Samsung
Gear 360
Garmin
VIRB 360
Samsung
Gear 360
No. of
Control
Points = 7
6.81 4.27 11.22 2.96 0.88 0.34
No. of
Check
Points = 22
12.25 17.75 24.11 10.72 0.85 0.42
Comparisons of reference points
Comparisons of reference line
• Samsung Gear 360 is better than
Garmin VIRB 360
• For comparisons of reference,
reference points are better than
reference lines

25. Analysis and Discussions
25
Angle delineation accuracy in indoor building
Angle
(unit:
degree)
Angle Measurement (Indoor)
Garmin VIRB 360 Samsung Gear 360
Reference
Line
Reference
Points
Reference
Line
Reference
Points
1 90 90 90 89
2 91.58 91.77 90 89
3 90.64 91.77 91 90
4 90 90 89 89.32
5 91.94 91.23 90 89.68
6 91 88.77 90 90
Total 545.16 543.54 540 537
Average 90.86 90.59 90.00 89.50
Min 90 88.77 89 89
Max 91.94 91.77 91 90
Std.
Deviation
0.8 1.2 0.63 0.46
RMSE 1.13 1.24 0.57 0.65
• Samsung Gear 360 is better than
Garmin VIRB 360
• For comparisons of reference,
reference line are better than
reference points
• Samsung Gear 360 is more
suitable for use in outdoor building

26. Analysis and Discussions
26
Angle
(unit: degree)
Angle Measurement (Outdoor)
Garmin VIRB 360 Samsung Gear 360
Reference
Line
Reference
Points
Reference
Line
Reference
Points
1 90 90 90 91.74
2 90 90 90 92.53
3 91.78 90 90 95.15
4 90 92 90 97.15
5 90 94 97.28 96
6 90 90 82.72 86
7 88 92 90 94.45
8 90 90 96 94.45
9 90 90 86 90.9
10 90 90 88 90.9
11 88 90 90 90
12 92 90 90 90
13 92 90 95 90
14 90 90 99 91.1
15 93 90 90 88.9
16 90 90 94 90
17 90 90 90 90.77
18 94.78 90 90 90.02
Total 1629.56 1628 1638 1650.06
Average 90.53 90.44 91 91.67
Min 88 90 82.72 86
Max 94.78 94 99 97.15
Std.
Deviation
1.64 1.09 3.95 2.79
RMSE 1.68 1.15 3.97 3.19
Angle delineation accuracy in outdoor building
• Garmin VIRB 360 is better than
Samsung Gear 360
• For comparisons of reference,
reference points are better than
reference lines
• Garmin VIRB 360 is more suitable
for use in outdoor building

27. Analysis and Discussions
27
Garmin VIRB 360 Samsung Gear 360
Indoor Outdoor Indoor Outdoor
No. of Photos used 497 262 719 565
GSD (unit: cm/pix) 0.6 0.7 0.71 1.9
No. tie points 115,563 180,457 166,596 393,943
No. of imaging rays 335,705 458,856 494,234 1,258,673
Image orientation
• For GSD, Garmin VIRB 360 is
better than Samsung Gear 360
• Indoor has fewer tie points than
outdoor
Results obtained in the image alignment

28. Analysis and Discussions
28
GARMIN VIRB 360 Samsung Gear 360
Indoor Outdoor Indoor Outdoor
Line Points Line Points Line Points Line Points
RMSE of Control
(unit:cm)
6.76 6.81 4.89 54.3 4.97 4.27 15.32 130.7
RMSE of
Reprojection
(unit:pixels)
4.64 6.44 1.49 1.41 2.47 2.34 1.08 6.07
RMSE of Angle
(unit: degree)
1.13 1.24 1.68 1.15 0.57 0.65 3.97 3.19
RMSE of Check
Point (unit:cm)
NA 12.25 NA 49.5 NA 17.75 NA 130.7
RMSE of Check
Line (unit:cm)
8.3 9.1 14.49 8.36 7.8 6.41 30.38 23.21
GSD
(unit: cm/pixel)
0.6 0.7 0.71 1.9
Comparisons of various accuracy index

29. TLS
Analysis and Discussions
29
Garmin VIRB 360
Samsung Gear 360
Comparisons of photogrammetric point cloud and TLS point cloud
Unit: cm
Samsung
Gear 360
Garmin
VIRB 360
Max Distance 20.4 21.1
Average Distance 2.6 4.3
Max Error 0.7 0.7
RMSE 0.26 0.31
Standard
Deviation
0.5 0.42

30. Conclusion
30
• Geometric point of view
• Reference lines are better
than using reference points
• For outdoor environment
• Garmin VIRB 360 is better
than the Samsung Gear
360
• For indoor environment
• Samsung Gear 360 is
better than Garmin VIRB
360
Garmin VIRB 360 Samsung Gear 360
Indoor Outdoor Indoor Outdoor
Reference lines X √ √ X
Reference points X √ √ X
Reference lines + points X √ √ X
Angle delineation X √ √ X

31. Future Works
31
3
2
1
Spherical images for documentation
and description of cultural heritage
through VR applications. Analyzing the algorithms for
calculating the calibration
parameters and any distortion
To compare accuracy assessment
using a terrestrial laser scanning,
Samsung gear 360 and Garmin
VIRB 360.