1. Tri-Closure Dr. Kotaro Yamafune (A.P.P.A.R.A.T.U.S. LLC)
Daniel Bishop (The University of Alabama)
Carolyn Kennedy (Texas A&M University)

2. Tri-Closure
A new method to create a local coordinate system that is essential to create geo-referenced 1:1 scale-constrained photogrammetric models.
Tri-Closure uses Photogrammetry to establish a local coordinate system
It require only 2 dives to establish fairly accurate coordinate system!

3. GEO-REFERENCED 1:1 Scale-Constrained Photogrammetric Model
To make 3D model into geo-referenced 1:1 scale-constrained model is essential if you need to use it as Archaeological data
Measurable 3D models
GIS Applications
Site Plan
AdriaS Project (Gnalic Shipwreck). Project Director Dr. Irena Radic Rossi

4. GEO-REFERENCED 1:1 Scale-Constrained Photogrammetric Model
To make 3D model into geo-referenced 1:1 scale-constrained model is essential if you need to use it as Archaeological data
Artifact Drawings
Digital Analysis (Interactive Fragment Model)
(Saveiro 1:10 wooden model)
Section Profiles
Point-Cloud-Based Deviation Analysis
AdriaS Project (Gnalic Shipwreck). Project Director Dr. Irena Radic Rossi

5. GEO-REFERENCED 1:1 Scale-Constrained Photogrammetric Model
Initial photogrammetry does NOT have any scale/accuracy!
Accuracy of the photogrammetric model = Accuracy of coordinate system applied.
NO MORE PRETTY PICTURES!!

6. Geo-referenced 1:1 scale-constrained Photogrammetric model
Conventional Methods
Create a local coordinate system separately (for examples, Total Station, Trilateration (DSMs).) Then apply created system into Photogrammetric models.
Geo-referenced 1:1 scale-constrained Photogrammetric model
Photogrammetric Model
Local Coordinate System

7. Conventional Methods Total Station Direct Survey Methods (DSM)
(Saveiro 1:10 wooden model)
Total Station
Direct Survey Methods (DSM)

8. Other Methods Scale Bars Direct Inputs Enclosure
(Saveiro 1:10 wooden model)
Scale Bars
Direct Inputs
Enclosure
It scale-constrains photogrammetric models, but not make it geo-referenced.

9. Trilateration (DSM) (cm)
Control (cm)
Trilateration (DSM) (cm)
Enclosure (cm)
Scale Bars (cm)
Total Station (cm)
R1 – R2
142.5
142.0
142.2
142.3
R1 – R3
51.2
51.3
51.1
51.0
50.7
R1 – R9
51.8
50.9
R1 – R6
63.4
63.9
63.2
62.9
R2 – R5
57.6
57.8
57.5
57.4
R2 – R11
50.4
50.5
50.3
R2 – R8
57.0
57.7
R3 – R5
44.9
44.6
45.2
45.1
45.5
R6 – R8
46.6
45.4
46.7
46.9
R3 – R6
54.2
53.9
54.4
54.3
54.0
R5 – R8
55.3
55.6
55.5
R4 – R7
57.2
57.1
56.7
R3 – R8
71.3
71.2
71.4
71.5
R6 – R5
71.0
70.4
71.8
71.7
Length of Keel
115.2
115.0
115.4
Average Error
0.39
0.20
0.19
0.33
Distances between reference points to compare different surveying methods to fix distortions and scales of the saveiro wooden ship models photogrammetric model

10. Assumptions 1 Direct Survey Methods (DSM)
Time-consuming for short-term projects
(DSM often requires more than 1oo measurements for one site)
Not designed for Photogrammetric Recording
(One positional error can distort the entire photogrammetric model)
However, DSM provides a local coordinate system!
(Enclosure, Scale Bars, Direct Input methods cannot provide this)

11. Assumption 2 Enclosure, Scale Bars, Direct Input methods
Simple, fast, and many cases these are more accurate!
It can provide Scale-constrained models (which is okay for individual artifacts), but it is impossible to create a local coordinate system, hence no geo- referenced models.
Photogrammetric models of a site cannot be combined based on scientific data.
Shelburne Shipyard Steamboat Graveyard Project
Directors, Dr, Kevin Chrisman and Carolyn Kennedy

12. Tri-Closure 1. Create 1:1 Scale Model
2. Place this model on the ground plane (geo-referenced field)
Mother Photogrammetric Model
3. Extract coordinates of reference points from the Mother Model, and use it for following photogrammetric recording (Child Models)
4. Merge Child Models to produce a Geo-referenced 1:1 Scale-constrained Photogrammetric Model

13. Tri-Closure
Enclosure
Mother Model
Scale Bars

14. Tri-Closure
1. Place 3 control points (Example 1) ① ② ③

15. Tri-Closure
1. Place 3 control points (Example 2) ① ②

16. Tri-Closure 1. Place 3 control points
As long as two edges keep same distance, it can be any distances.
 Very Flexible 

17. Tri-Closure
2. Calculate X Y coordinates of the 3 control Points

18. Tri-Closure
3. Modify the 3 coordinates with depth (add Z coordinates)

19. Tri-Closure = Mother model
4. Input the modified coordinates to the initial photogrammetric model (Also scale-constrain the model using the scale-bar method.)
= Mother model

20. (1:1 Scale-Constrained model of the Site)
Tri-Closure
5. Start photogrammetric recording (Child Models)
Child Models
Complete Model
(1:1 Scale-Constrained model of the Site)
Mother Model
Local Coordinate System
AdriaS Project (Gnalic Shipwreck). Project Director Dr. Irena Radic Rossi

21. Mother Model (Geo-referenced 3D model)
Tri-Closure
6. Use Mother Model’s coordinate systems to scale-constrain the Child Models
Mother Model (Geo-referenced 3D model)
Child Model
View Estimated
Coordinates of
the Reference Points
Use Mother’s
Coordinates Here
Create markers (reference points) at mutual positions on both
The Mother and the Child models
Use Mother Model’s coordinates on Child models’ reference points (Geo-referenced Scale-Constrain)
AdriaS Project (Gnalic Shipwreck). Project Director Dr. Irena Radic Rossi

22. Tri-Closure Geo-referenced 1:1 Scale-Constrained Photogrammetric Model
Complete Model
(Geo-referenced 1:1 Scale-Constrained model of the Site)
Site Plan
Digital Analysis (Interactive Fragment Model)
Archaeological Applications
Measurable 3D models
Point-Cloud-Based Deviation Analysis
GIS Applications
AdriaS Project (Gnalic Shipwreck). Project Director Dr. Irena Radic Rossi

23. Tri-Closure
Triangle can be added!

24. Comparison Tri-Closure Underwater Place 3 control points
Apply Initial Photogrammetric Recording
(Only dives are required)
On-land
Calculate and modify 3 coordinates
(Also scale constrain using Scale-bars)
Create Mother Model
Use Mother Model’s coordinate system
(Unlimited numbers of reference points)
Direct Survey Methods (DSM)
Underwater
Set-up Control Points (and Reference Points)
Create Control Network
Measure Control points to Reference Points
5-10 Days (50 to more than 100 of measurements are required)
On-land
Create Local Coordinates System
(Statistical Adjustment of Trilateration)
Use created local coordinate system for photogrammetric recording
(Additional measurements are required for new reference points)

25. Conclusion Advantage of Tri-Closure
Requires minimum amount of underwater working time
Simple and fast
Very flexible (Any distances can be used to set up 3 Control Points) (Positions and numbers of Reference points are not determined)
Accurate (using Enclosure and Scale-bar methods to scale-constrain)
Disadvantage
Exclusively designed for Photogrammetric recording (Requires knowledge of Photogrammetry and CAD software)

26.  Thank you 