Bulens, J.D.

Rip, F.I.

NARCIS 

IM-Tree: Towards an information model for an integrated tree register

Name not available

Wageningen Yield 

1 Introduction 
The value of trees other than their wood production capacity 
is getting more and more attention, both in cities and in rural 
areas. Research [7, 8] quantified the value of trees in New 
York City and Chicago at 700-1000 US$ each. This includes 
the potential of trees in their role as providers of ecosystem 
services. Examples of such services are the scavenging of 
particulate matter, storage of CO2 [9] and mitigation of the 
Urban Heat Island effect [11]. 
 
Europe recognises this value and its policy aims at an 
increase in the number of trees or more commonly an increase 
of Green area (nature) and at the same time a decrease of 
agricultural areas because of a surplus in agricultural 
production. The European Commission decided to subsidize 
by 2014 the taking-out-of-production of 7% of a farmer’s 
land. This should support the increase of biodiversity 
(“Greening the Common Agricultural Policy (CAP)”) by 
means of the presence of small landscape elements (< 5 
hectares) like bushes, trees and hedges [12].  
 
For safety reasons tree owners in the Netherlands have a 
public responsibility, a legal “obligation to care”, to keep trees 
vital and healthy. The objective is the reduction of the danger 
of falling branches or trees falling over in public space. This 
obligation requires tree owners to keep record of individual 
tree condition. However, each owner does that in a different 
way with regard to information content and update frequency. 
Another aspect of the situation: there is no obligation to report 
the tree condition to a central point so it is unknown which 
tree information is collected by the various owners.  
 
2 Point of departure 
To value trees it requires data about their presence and their 
properties for areas as a whole. That is, you want data about 
trees of different owners, both public and private 
organizations, even of private persons. Basically what is 
needed is a register, which contains all the non-forest trees, of 
all owners, public and private. In the Netherlands, that does 
not exist. 
 
This results in the situation that for instance the 
municipality of Amsterdam manages 240.000 trees, whereas 
the number of urban trees in the municipality might well be 
25% higher [4]. Including trees of other owners and forest 
trees, the total for Amsterdam is estimated at around 500.000 
trees. Such differences and uncertainties limit the potential to 
effectively battle pests and diseases: the source of 
contaminations might be in trees of the neighbouring owner. 
This fragmented situation also is an obstacle for calculations 
regarding ecosystem service levels. Also, there is no reference 
for landscape elements that might qualify for the CAP 
subsidies. 
 
We conclude that there is a need for an integrated register 
on trees, both for urban and rural areas. 
 
3 To an integrated tree register 
In the Netherlands, conditions seem favourable to experiment 
with combining existing tree data in an integrated manner: 
 There is an interest among tree professionals for 
assessments like those in New York and Chicago. The i-
Tree software, developed by USDA 
(http://www.itreetools.org/) is freely available. 
Unfortunately, it is adapted to the North American 
situation, which means that adaptation to European 
climate zones is necessary. 
 In the period 2008-2013 the elevation has been mapped 
nationwide with LiDAR. From the resulting point cloud 
cover elevation grids were derived with a horizontal 
resolution of 50 cm. (http://www.ahn.nl/). One grid 
models the surface of the terrain including objects on top 
of it: the DSM. By filtering out the objects a second 
dataset is created that describes only the terrain surface: 
the DTM. From DSM and DTM spatial objects can be 
detected. 
 Wageningen UR – Alterra researcher Clement used that 
data set to extract tree canopy perimeters with about 60% 
IM-Tree. Towards an information model for an integrated tree register 
 Frans I. Rip 
Wageningen University 
Droevendaalsesteeg 3 
Wageningen 
Frans Rip@wur.nl 
Jandirk Bulens 
Wageningen UR - Alterra 
Droevendaalsesteeg 3 
Wageningen 
Jandirk.Bulens@wur.nl 
 
 
Abstract 
This paper gives an overview of the first steps towards a tree information model against the background of the situation in the 
Netherlands. Fragmented ownership and incomplete data are an obstacle for effective tree management and for quantitative evaluation. The 
greening ambition of Europe’s  Common Agricultural Policy also requires tools and datasets to check claims to subsidize small landscape 
elements. Tools referred to are a tree crown perimeter dataset and a method to derive a 3D model from that perimeter.  
Keywords: Tree, Information Model, Common Agricultural Policy, Silvistar, 3D. 
AGILE 2013 – Leuven, May 14-17, 2013 
 
completeness [10]. It is to be expected that improvement 
of the detection results is possible by additional use of 
aerial photographs and remote sensing techniques [1].  
 From the Clement canopy projections, a set of tree shape 
parameter values can be derived, which are useful for 
collecting individual tree data and generate 3D 
visualizations [6].  
 CROW, the Dutch technology platform for transport, 
infrastructure and public space, has started a project to 
standardize the tree risk assessment procedure. CROW’s 
motivation is that there is a variety of Visual Tree 
Assessment methods in use. The objective of CROW is 
to arrive at clear inspection assignments, full 
exchangeability of datasets resulting from inspections 
with tree management software systems, a standard 
reference for assessment specifications. Achieving these 
targets should provide certainty that the assessment 
results can be dealt with effectively [3]. 
 Geonovum, the Dutch National Spatial Data 
Infrastructure executive committee, published the second 
edition of IMGeo in December 2012 [2]. IMGeo is used 
to build the Base Register for Large Scale Topography. It 
contains data specifications in the Netherlands for 
topographic objects from scale of 1:500 to 1:5000. This 
constitutes a national standard for storage and exchange 
of topographic objects. IMGeo contains CityGML and 
complies with this standard. 
 
Current policy in the Netherlands supports strongly the close 
cooperation between public and private parties to create new 
business. This and given the conditions above led in 2012 to 
the set up of a Public-Private Partnership (PPP) between 
Wageningen UR and two private sector companies: NEO bv 
(remote sensing) and GEODAN bv (Geo-ICT). Its objective: 
to investigate the possibility for web services about tree data.  
 
4 Tree data specifications 
Because – at least in the Netherlands - there was no agreed 
standard for structuring data about trees, one of the tasks for 
2012 of the PPP was to set up data specifications and design 
an Information Model for tree data. This should be an 
extension of the existing information model for Geometry 
(IMGeo). The data specifications for trees should be 
compliant with IMGeo containing the basic ‘green’ 
topographic objects.  
 
The methodology used is based on experiences of the data 
specification process in INSPIRE also following ISO19131. 
In short: 
 Identify use cases 
 Identify requirements and spatial objects 
 Analysis for completeness 
 Data specification development 
 Test and validate 
At the time of writing the data specification development 
for trees is still going on. 
 
 
 
4.1 Use cases 
In order to develop the information model, a number of use 
cases were identified. They were used to discover what 
objects and properties should be included in the model. The 
most important cases are: 
 Visual Tree Assessment / Tree Risk Assessment. Assess 
the health condition of individual trees to assure the 
safety for citizens. The stability of a tree might be 
influenced by diseases, storms, pests or by old age, 
which has to be checked regularly. 
 Tree visualisation. Generate 3D scenes of tree landscapes 
in urban and/or rural environments for aesthetic designs 
and to support planning, planting and maintenance. and 
report about it. 
 Notifications and requests. Messages sent to the tree 
owner about specific trees. For instance requests for 
cutting permits, or notifications about blown over trees, 
fallen branches or signs of disease. It might be a message 
about the presence of a pest, like the Oak Procession 
Caterpillar. It could also be a complaint about trees 
getting too high, producing too much shadow. Another 
cause for complaints could be the production of pollen, 
which can be a nuisance for persons with an allergy. 
 Tree monuments. A tree can be considered meaningful 
and worth protection. Properties like size or age or a 
connection to important persons, places or occasions 
could be the foundation for a protective policy. This 
would influence maintenance decisions. Complaints 
about trees should be checked against its protection 
status. 
 CAP. Establishment of landscape elements on plots of 
arable land to enable biotope networking, e.g. planting of 
hedges or copses with indigenous species. Construction 
of dry stone walls or planting of tree lines along field 
Figure 1  The INSPIRE methodology for use case 
development 
AGILE 2013 – Leuven, May 14-17, 2013 
 
 class IM-Tree
«featureType»
SolitaryVegetationObject
+ function:  GenericName [0..*]
+ usage:  GenericName [0..*]
+ species:  GenericName [0..1]
+ height:  Length [0..1]
+ trunkDiameter:  Length [0..1]
+ crownDiameter:  Length [0..1]
«attribuuttype»
+ class:  GenericName [0..1]
«ADEElement»
ADE-AssessedTree
+ treeID:  identifier
+ treePosition:  GM_Point
+ treeAssessed:  boolean
+ treeSafetyClass:  TreeSafetyClassType
+ treeMeasure:  TreeMeasureType
«ADEElement»
ADE-SilvistarTree
+ treeTop:  GM_Point
+ treeCrownBase:  GM_Point
+ treeFork:  GM_Point
+ treeBase:  GM_Point
+ treeStemBase:  GM_Point
+ treeCrownPeriphery:  GM_Point [4]
«ADEElement»
ADE-SolitairyVegetationObject
+ SolitaryVegetationObjectType:  TypeVegetatieObject
Figure 4  IM-Tree as extension of IMGeo 
Figure 3  Silvistar 
3D tree shape 
parameters [5] 
borders etcetera. A farmer could receive compensation 
for doing this, but there are conditions to be met. 
These use cases roughly cover the descriptive needs of 
utilitarian and aesthetic management of non-forest trees in 
both urban and rural settings. 
 
4.2 Identify spatial objects 
The use cases define the “Universe of Discourse” (UoD), 
meaning that part of the real world we are interested in. The 
next step is to define the spatial objects as carriers of 
information, being the smallest meaningful entities within the 
UoD. Once identified, one can specify what properties of the 
object are relevant. For our cases we have the tree safety 
properties from the tree assessment case, the tree shape 
properties from the visualisation case, the attributes of 
complaints or pest notifications and the protection status of a 
tree. The CAP case provides an additional perspective, being 
not only about individual trees, but about a combination of 
trees and shrubs in relation to an area of land in agricultural 
use. 
 
4.3 IM-Tree 
Since IMGeo and CityGML are at the 
base of the Tree model, the basic 
object is a VegetationObject defined 
in CityGML [13]. For an individual 
tree there is a subtype 
SolitaryVegetationObject that is 
extended in IMGeo as an Application 
Domain Extension (ADE) Element 
with a SolitaryVegetationObjectType 
property with two possible values: 
“Tree” and “Hedge” (fig 2). 
 
In several use cases tree shape 
parameters are used to model the tree in three dimension. The 
forestry-based Silvistar model [5] is used for the purpose. This 
is different from the tree growth parameters used in SILVA 
[14], as it does not include the stem diameter, but has more 
detail on the crown perimeter shape. In short, the model uses 
3-dimensional coordinates (xyz) to describe the shape of the 
tree (fig 3). 
 
The Silvistar parameters are: 
 Height Top (T) 
 Height Crown Base (C) 
 Height Fork (F) 
 Height Base (B) 
 Crown Periphery points (P1, P2, P3, P4) 
 
For the Visual Tree Assessment the properties used are the 
following: 
 Tree ID 
 Tree Height (already iincluded in IMGeo) 
 Tree Position 
 Tree Assessed 
 Tree Safety Value 
 Tree Safety Measure 
 
Given the requirements for these two use cases only, the 
extension of the model can be modelled as shown in Figure 4.  
 
5 Discussion and future work 
IM-tree at this stage is merely a reconnaissance of the 
usefulness and need for tree data specifications. We would 
like to continue the specification process in close cooperation 
with stakeholders related to the identified use cases. We like 
to announce our involvement with this subject by means of 
 class Vegetatie
«featureType»
Vegetation::
_VegetationObject
«featureType»
Vegetation::VegetatieObject
+ function:  GenericName [0..*]
+ usage:  GenericName [0..*]
+ species:  GenericName [0..1]
+ height:  Length [0..1]
+ trunkDiameter:  Length [0..1]
+ crownDiameter:  Length [0..1]
«attribuuttype»
+ type:  GenericName [0..1]
«featureType»
Vegetation::PlantCover
+ function:  GenericName [0..*]
+ usage:  GenericName [0..*]
+ averageHeigth:  Length [0..1]
«BGT, attribuuttype»
+ fysiekVookomen:  GenericName [0..1]
_Feature
«featureType»
CityGML Core::
_CityObject
Figure 2  The SolitaryVegetationObject 
 
AGILE 2013 – Leuven, May 14-17, 2013 
 
this paper, mainly to start an international discussion, 
especially with regard to the Common Agricultural Policy. 
We expect that there may be other information models, and it 
could be fruitful to compare approaches. 
 
References 
[1] Ardila López, J.P. Object-based methods for mapping 
and monitoring of urban trees with multitemporal image 
analysis. Univ. of Twente, ITC dissertation nr.209, 2012. 
http://www.itc.nl/library/papers_2012/phd/ardila.pdf  
 
[2] Brink, L. van den, H. van Eekelen, M.Reuvers. 
Basisregistratie Grootschalige Topografie: 
Gegevenscatalogus IMGeo 2.1. Geonovum, Amersfoort, 
December 2012 (in Dutch). 
 
[3] Iperen, C. van. CROW start met ‘Standaardisatie VTA-
systematiek’. In: Groot, J.de, Congresboek Nederlandse 
Boominfodag 2012, Lunteren, p.50 (in Dutch). 
 
[4] Kaljee, H. Oral communication of Amsterdam tree 
consultant to F.Rip at meeting in Amsterdam, Oct.15th, 
2012.  
 
[5] Koop, H. (1989). Forest Dynamics, SILVI-STAR: A 
Comprehensive Monitoring System. Springer, Berlin 
Heidelberg New York Tokyo.  
 http://edepot.wur.nl/201980  
 
[6] Kramer, H., J.Clement. 3D Tree Extraction from LiDAR: 
Trees as 3D geo objects. Presentation at the ESRI User 
Conference, San Diego, USA, July 2012 
 
[7] Nowak D.J., R.E.Hoehn III, D.E.Crane, J.C.Stevens, 
J.T.Walton. New York City’s Urban Forest. USDA 
Forest Service, 2007.  
 http://www.milliontreesnyc.org/downloads/pdf/ufore_stu
dy.pdf   
 
[8] Nowak, D.J., R.E.Hoehn III, D.E.Crane, J.C.Stevens, 
C.Leblanc Fisher. Assessing urban forest effects and 
values, Chicago's urban forest. USDA Forest Service, 
2010. http://www.treesearch.fs.fed.us/pubs/34760  
 
[9] Oudenhoven, A.P.E. van, K.Petz, R.Alkemade L.G.Hein, 
R.S. de Groot. Framework for systematic indicator 
selection to assess effects of land management on 
ecosystem services. Ecological Indicators, vol.21 - p. 110 
- 122, 2012. http://edepot.wur.nl/232691  
 
[10] Schouten, I., M.Flanagan, J.Clement. Bomen modelleren 
met laseraltimetrie. Geo-Info 2012-7, p.3-7. (in Dutch). 
http://www.geo-info.nl/   
 
[11] Steeneveld G.J., S.Koopmans, B.G.Heusinkveld, L.W.A. 
van Hove, A.A.M.Holtslag. Quantifying urban heat 
island effects and human comfort for cities of variable 
size and urban morphology in the Netherlands. Journal of 
Geophysical Research: Atmospheres, 2011. 
http://dx.doi.org/10.1029/2011JD015988 
 
[12] Zeijts, H. van, K.Overmars, W. van der Bilt, N.Schulp, 
J.Notenboom, H.Westhoek, J.Helming, I.Terluin, 
S.Janssen. Greening the Common Agricultural Policy: 
impacts on farmland biodiversity on an EU scale. PBL 
Netherlands Environmental Assessment Agency, report 
nr.500136005, 2011.  
 http://www.pbl.nl/en/publications/zeijts 
 
[13] OGC. City Geography Markup Language CityGML 
Encoding Standard v.2.0. OGC, April 2012. 
 
[14] Rossmann, J., M.Schluse, R.Waspe, R.Moshammer. 
Simulations in the woods: From remote sensing based 
data acquisition and processing to various simulation 
applications. In: Proceedings of the 2011 Winter 
Simulation Conference. Phoenix, Arizona, 11-14 Dec. 
2011. http://www.informs-sim.org/wsc11papers/088.pdf  
 


IM-Tree: Towards an information model for an integrated tree register

Abstract

Similar works

Full text

Available Versions

NARCIS

Name not available

Wageningen Yield