LOADING THE TREE · 正在载入模型
樱花为证

Cherry Blossoms
as Witness

A digital twin and seasonal AR interpretation of the sakura trees on Aixiao Road, Tongji University.

CourseDigital Heritage Landscape ObjectSakura Avenue · 爱校路樱花树 Group Members吕思扬 · 李欣芸 · 张弥月 · 李成蹊 · 唐家辉 · 卓虹礼
02The object · 遗产对象

It is November.
The tree is bare.

Sakura Avenue blooms for about two weeks a year. For the other fifty, its meaning is invisible. That gap is our design problem.

CAD location plan of the Aixiao Road cherry grove, Siping campus
CAD-BASED LOCATION PLAN · SIPING CAMPUS · INDICATIVE SCALE
Character
Avenue
Paired rows of cherry trees forming a linear, seasonal corridor
Scale · 1997 → now
100→ 200+
Gifted saplings in 1997; 200+ trees reported blooming in 2023
Study corridor
33trees
18 on the tennis-court side + 15 on the football-field side
Scope
1 + setting
One tree as twin, the avenue and stone as its context
03History · 历史溯源

A gift, a deadline,
and a domestic substitute.

The school archives hold almost nothing on the trees. Their story survives in newspapers, alumni newsletters and oral history.

1996DEC

School of Computer Science signs with Japan's CSK; Tongji–CSK System Software Research Center founded.

1997MAY 17

Tongji's 90th anniversary. CSK gifts 100 cherry trees in thanks.

90th anniversary stage
《校友通讯》No.1, 1997
1997MAY 20

Import checks were too slow, so the saplings were bought in China. They were planted on Aixiao Road and in Sanhao Wu, and the stone was unveiled.

2014MAR 27

A retired couple photographs seven graduates under the blossoms, then writes to find them.

Graduates photo and letter
Tongji News, 2014-04-18
2019APR

Former dean Xuan Guorong, who signed the 1996 deal, is interviewed beneath "his" trees.

2026

Digital twin and four-season AR of one sample tree.

Sources: People's Daily 1997-05-18 · Tongji News 2014 / 2019 · CCF-CV interview 2022 · Shanghai Gov. 202303 / History
04The inscription · 碑文
Memorial stone, 1997
樱花为证
中日友好
世代为继

“Cherry blossoms as witness —
China–Japan friendship,
carried on through generations.”

MEMORIAL STONE · TONGJI UNIVERSITY & CSK JAPAN · MAY 1997
05Living memory · 校园记忆
These trees are like my children. Every spring I come back to see how they have grown.

“这些樱花树就像是我的孩子,每年这个时间,我都要来这里看看。”

Prof. Xuan Guorong, former Dean, School of Computer Science · Tongji News, 2019

Prof. Xuan and his wife under the trees, 2024
Graduates receive their photo
Letter and photo

The photograph that found its owners

In 2014, a retired couple photographed seven graduates in gowns beneath the blossoms. They wrote to the university to find the students, and within two hours of a Weibo post, the students replied. The tree became the setting for a stranger's kindness.

Photos: Xiaohongshu @诺坎普の猫 (2024-03-29) · Tongji News (2014-04-18)
06Site · 场地平面

Thirty-three trees,
one corridor.

18

Tennis-court side, R01–R18, at about 5 m centres, so about 85 m from first to last stem.

15

Football-field side, L01–L15. The spacing here has not been measured yet.

12.5m

Between the two tree-row axes, read from the campus CAD drawing.

CAD grove plan with study tree T01
STUDY TREE · T01

Our digital twin is R01, the first tree on the tennis-court side, at the Nan Avenue end of the grove.

CAD-BASED GROVE PLAN (同济大学含植物.dxf) · TREE SYMBOLS ARE NOT MEASURED CROWNS · COUNTS FROM OUR FIELD SURVEY
07Site · 空间关系

A street beneath the trees.

Sports edgeWalkShared road · 骑行与步行WalkShrubs · benches ≈ 12.5 m between CAD tree-row axes In spring the two crowns almost meet over the road A–A · ANALYTICAL SECTION · HEIGHTS, WIDTHS AND LEVELS ARE SCHEMATIC
LINEAR SPACE

Two paired rows turn an ordinary campus road into a corridor.

SHARED MOVEMENT

Walking and cycling share the centre, under the canopy.

EDGE PAUSE

Shrubs and benches at the edges let people stop and look up.

Aixiao Road corridor, people walking and cycling
Field photo · Aixiao Road in early spring. Movement readings are qualitative; no traffic counts are claimed.
Planting layers under the cherry trees
Field photo · canopy, shrub and ground layers along the avenue
08Site · 植物群落

Three layers under one canopy.

CANOPY · 乔木层

Cherry

  • Japanese early cherry日本早樱 · per tree label
SHRUB · 灌木层

Evergreen

  • Euonymus japonicus冬青卫矛
  • Viburnum odoratissimum珊瑚树 · hedge on both sides
GROUND · 地被层

Herbaceous

  • Ophiopogon japonicus麦冬
  • Orychophragmus violaceus诸葛菜 · purple in spring
TENNIS-COURT SIDE · 18 TREES · ≈ 5 m CENTRES · ≈ 85 m R01R02R03R04R05R06R07R08R09R10R11R12R13R14R15R16R17R18 T01 FOOTBALL-FIELD SIDE · 15 TREES · SPACING NOT MEASURED L01L02L03L04L05L06L07L08L09L10L11L12L13L14L15
09Significance assessment · 价值评估

Four values, one avenue.

Following the Burra Charter's categories of cultural significance, applied to a living landscape element.

01

Historic历史

Physical evidence of Tongji's 1990s reform and international cooperation. It is dated, documented, and paired with an inscription.

CSK agreement 1996 · stone 1997
02

Social社会

An annual ritual landscape for graduates, alumni, founders and city visitors. Its meaning is renewed by use.

2014 photo story · 2019 / 2024 visits
03

Aesthetic美学

A short, intense seasonal spectacle. Pale pink blossom forms a continuous canopy over the road.

≈ 2-week bloom · late March
04

Scientific科学

A living record of growth since a known 1997 planting date, and a baseline for phenology and tree-health monitoring.

29 years of growth · digital baseline
OPEN QUESTION

Sources disagree on the species: a 2023 city report says Somei Yoshino (染井吉野), but the tree's label reads 日本早樱 · Prunus subhirtella. Verifying the species is the next step of fieldwork.

10Digital twin · 建模流程

From a partial scan
to a traceable tree.

01 · CAPTURE

Field data现场资料

A 3D scan mesh with bark colour, 8 photographs from different sides, and tape girths: 120 cm at the base, 60 cm on each stem.

.fbx · photos · tape
02 · CLEAN

Keep the scan保留原扫描

The surroundings are cropped away. 16,894 scanned triangles are kept untouched and checked vertex by vertex.

Rhino · rhino3dm
03 · REPAIR

Patch the gaps缺面补修

Holes in the root collar and broken limbs are filled from local cross-sections, on a layer of their own.

section rings
04 · COMPLETE

Rebuild the crown枝系补全

6 scan-fitted axes and 50 limbs read from photos, then 1,566 rule-based twigs and short shoots.

layered .3dm · 1,622 axes
05 · PUBLISH

Seasons + AR季相与 AR

A light GLB and the branch axes drive the seasons in Three.js and the emblem AR in MindAR.

glTF · Three.js · MindAR
16,894scanned triangles kept437,947triangles in total1,622branch axes12 MBweb model
11Reconstruction · 分层重建

Five steps, from a stump of data to a full crown.

Skeleton built in five stages
a · raw scanb · 6 scan-fitted axesc · + 50 photo-read limbsd · + 522 rule twigse · + 1,044 short shoots
Components · 构件数量
Scan-fitted axes6
Photo main limbs9
Photo secondary41
Rule twigs522
Rule short shoots1,044
Summed axis length · 累计轴长 (m)
Scan-fitted axes14.0
Photo main limbs36.6
Photo secondary66.7
Rule twigs174.7
Rule short shoots106.8
70.6%

of the summed axis length comes from rule-generated twigs. Any statistic about the fine crown says as much about our rules as about the tree.

12Evidence layers · 证据分层

Every branch says where it came from.

Original scanL1 原始扫描

Root collar, the twin stems and parts of the main limbs.

Surface repairL1 缺面修补

Holes filled from cross-sections of the scanned surface.

Photo limbsL2 照片逐枝

Main limbs traced branch by branch from the photographs.

Secondary branchesL3 次枝

Smaller branches read from the photos where visible.

Rule-based twigsL3 规则细梢

Fine twigs and shoots generated by rules, not observed.

Field photograph of T01
FIELD PHOTOGRAPH · T01
Model coloured by evidence layer
MODEL COLOURED BY SOURCE · 按来源着色

Colour means provenance, not confidence. Following the London Charter, interpretation stays visible and separate from the record.

13Drawn record · 正投影图纸

The twin as a set of drawings.

Plan XY
PLAN · XY

Span 7.47 m (X) × 8.56 m (Y)

Elevation XZ
ELEVATION · XZ

Highest model point Z = 6.87 m

Elevation YZ
ELEVATION · YZ

Viewed along the model X axis

HORIZONTAL SECTIONS · 水平截面
Section Z 0.26 m

Z = 0.26 m
Root collar: irregular, not round.

Section Z 0.70 m

Z = 0.70 m
The trunk splits into two stems.

Section Z 1.30 m

Z = 1.30 m
Two separate stems at breast height.

1 mmodel units · metresZ = 0local ground referenceAxes are local model directions, not yet registered to north.
14Measurement ledger · 尺寸台账

Measured, modelled, and still unknown.

FIELD · TAPE

Measured现场实测

Base girth≈ 120 cm
→ equivalent diameter38.2 cm
Each stem, mid-height≈ 60 cm
→ equivalent diameter19.1 cm
MODEL · READING

Modelled模型读数

Highest point6.87 m
Span X × Y7.47 × 8.56 m
Branch hull (Z ≥ 1.5 m)33.21 m²
Hull centroid off the root2.19 m
TO SURVEY · 待补测

Unknown仍需测量

True tree height?
Crown spread, north-oriented?
Diameter at 1.3 m (DBH)?
Heights where girths were taken?
Scan points and fitted circles on stem A
STEM A · SCAN POINTS AND FITTED CIRCLES AT Z ≈ 0.26 / 0.70 / 1.30 m · CENTRE OFFSETS 13.4 / 8.6 / 0.4 cm · D = C / π ASSUMES A ROUND TRUNK, WHICH IT IS NOT
15Structural analysis · 结构分析

Reading the architecture of one tree.

Orientation rose and elevation Axis length by height Projected axis density Convex hull and eccentricity Field photo versus model
16Inside the twin · 模型解读

Three ways
to read a tree.

DRAG TO ROTATE · SCROLL TO ZOOM · KEYS A / B / C

6.92 m
HEIGHT · 树高
7.47 × 8.56 m
CROWN SPAN · 冠幅
17Four seasons · 四季
Spring春 · 一树花开

FLOWERING CALENDAR · 物候示意
18AR in use · 实机演示

On the phone, in place.

A screen recording of the web AR. The emblem is shown on a laptop screen, and the seasons are switched without leaving the camera.

TRACKING

The tree stays anchored to the emblem as the phone moves, so it reads as standing on the target.

SEASONS IN PLACE

One tap switches the season. The same branch structure carries blossom, leaves, colour or nothing.

CONTROLS

Density and model-scale sliders, auto-rotate, and a camera-only mode for placing the tree by hand.

STILL TO TEST

Outdoor light, a printed emblem on site, and performance on older phones.

19Augmented reality · 增强现实

The emblem
is the anchor.

I chose the Tongji emblem as the AR target on purpose. The trees exist because of the university's 90th anniversary, so the university's own symbol summons them.

1

Scan the QR code. It opens in the phone browser, so there is nothing to install.

2

Point at the emblem. It can be printed, on a screen, or on any campus sign.

3

Switch seasons in place. Drag to rotate and pinch to scale. Offline mode is available.

Tongji emblem target
● EMBLEM TRACKEDEXIT AR
原始春夏秋冬
Your turn · 扫码体验
ar.nyxal.site
Emblem target
↑ IMAGE TARGET · 识别图
20Interpretation · 阐释策略

Four layers of time in one tree.

LAYER 01 · 1997

The Gift赠礼

The founding event, read through the stone, the newspapers and the 1996 agreement.

ARCHIVE · INSCRIPTION
LAYER 02 · EVERY SPRING

The Ritual花期

The annual return of graduates, alumni and the dean who "raised" the trees.

ORAL HISTORY · PHOTOS
LAYER 03 · 29 YEARS

The Growth生长

The branching skeleton as the tree's own record of time: 1,622 axes, each tagged with its source.

DIGITAL TWIN · SKELETON
LAYER 04 · ANY DAY

The Witness见证

AR makes the meaning visible in any season. "Witness" stops being seasonal.

WEB AR · EMBLEM ANCHOR
Principle · 阐释原则

Real structure. Simulated seasons. Documented stories. Every layer says which it is.

21Honest boundaries · 解释边界

What the model can, and cannot, claim.

Model findingWhat it supportsStill to check
The twin stems and main fork come from the scanThe lower structure has direct geometric evidence.How well the full trunk matches the real tree.
Rule twigs are 70.6% of summed axis lengthCrown statistics are sensitive to our rules.The real number and spread of fine twigs.
The branch footprint is 2.19 m off-centreThe modelled crown is clearly asymmetric.True crown spread and north orientation.
Low sections are off-centre to fitted circlesThe trunk base is irregular, not round.Non-circular profiles and scan gaps.
Every source is kept on its own layerThe model can be edited and traced.Dimensional accuracy and AR performance.
PRIORITY 1 · 尺度

Survey true height and ground level, crown spread in two directions with north, and girth heights.

PRIORITY 2 · 形态

Photograph hidden sides and key forks; re-cut irregular sections with real outlines.

PRIORITY 3 · 展示

Test AR on site and on older phones; simplify twigs for mobile.

22Reflection · 反思与展望

Where it
goes next.

SEASONS

Blossom and leaf data are a display simulation. Next, calibrate against phenology observations recorded each spring.

SPECIES

Resolve the Somei Yoshino vs. Prunus subhirtella conflict with botanical verification.

SCOPE

Scale from T01 to all 33 trees in the corridor, then the whole avenue, and add an oral-history audio layer in AR.

ARCHIVE

Institutional records were thin, so collect testimony from the 1997 generation while it is still possible.

世代为继

Thank you.

QUESTIONS WELCOME · 欢迎提问

23Appendix · 参考资料

Sources and methods.

Heritage frameworks

  • Australia ICOMOS (2013). The Burra Charter.
  • The London Charter (2009). Computer-based Visualisation of Cultural Heritage, v2.1.
  • ICOMOS (1996). Principles for the Recording of Monuments, Groups of Buildings and Sites.
  • Historic England (2017). Photogrammetric Applications for Cultural Heritage.

Tree reconstruction

  • You, L. et al. (2023). Tree Skeletonization with DBSCAN Clustering Using TLS Data. Forests 14(8), 1525.
  • Raumonen, P. et al. (2013). Fast Automatic Precision Tree Models from TLS Data. Remote Sensing 5(2).
  • Fan, G. et al. (2021). Low-cost Reconstruction of Tree Structure by AdQSM with Close-Range Photogrammetry. Forests 12(8), 1020.
  • Methods were used as references; the algorithms were not fully reproduced.

History & site

  • People's Daily, 1997-05-18 · 《校友通讯》 No.1, 1997.
  • Tongji News, 2014-04-18; 2019-04-15 《樱花树下忆当年》.
  • Shanghai Municipal Government, 2023 cherry report.
  • Campus CAD 同济大学含植物.dxf · our field survey, photos and girth records.
  • Photo: Xiaohongshu @诺坎普の猫 (2024).
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