Using Virtual Forest Environment on Collaborative Forest Management

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Using Virtual Forest Environment on Collaborative

Forest Management

Mingyao Qi

, Tianhe Chi

, Xin Zhang

Institute of Geographic Sciences and Natural ResourcesResearch, CAS, Beijing, China, 100101

e-mail: [email protected]

Institute of Remote Sensing Applications,CAS, Beijing, China, 100101

Jingxiong Huang

ATR Lab, Shenzhen UniversityShenzhen, China,518060

AbstractIn this paper, we introduce our methods on how to use

Virtual Forest Environment for collaborative forest

management. We first discuss the construction issues of a virtual

forest environment and bring forward a method to automaticallygenerate forest stand model through 2D GIS data, forest

inventory data and Remote Sensing. Then, to meet the needs of

opinion representation, we realize selecting and labeling directly

on the scene with VRML and java. And then, to support

collaborative group work, we integrate some methods in

Computer Supported Cooperative Work (CSCW) and

Collaborative Virtual Environment (CVE) and design three

models: collaborative perception model, behavior model and

collaboration model. Finally, we introduce our prototype system:

a virtual forest planning environment system for people from all

backgrounds, including public community, domain experts and

government managers. Its proved that the combination of VR,

CSCW and RS technologies is a feasible and innovative way to

support forest management..

Keywords- RS, VR, CSCW, CVE, GIS, forest management

I. INTRODUCTION

Since Our National Landscape meeting on appliedtechniques for analysis and management of the visual resourcehold in Nevada, US in 1979, the past two decades has seenmuch progress on constructing Virtual Forest Environment(VFE) as a visual management tool for its sustainabledevelopment, such as AMAP[1], IMAGIS[2], Smart Forest[3][4] and so on. These tools can be used for forestvisualization and simulation, however, they can neither let userimmerse in the virtual environment, nor do they support multi-

users to attend the same scene and communicate with eachother in an intuitive way, say, draw a blueprint directly on the3D scene.

In this paper, we introduce our methods on how to useVirtual Forest Environment for collaborative forestmanagement. A Collaborative Virtual Forest Environmentsystem is a Collaborative Virtual Geographical Environment[5] that enables wide range people, including governmentofficers, residents and domain experts to participant in different

places at the same time or different time, by which they can join in, navigate, query, select, label and communicate with

others, so as to formulate a cutting and planting plan based onthe sustainable development policy. In this paper, we firstdiscuss the construction issues of a virtual forest environment

and bring forward a method to automatically generate foreststand model through 2D GIS data, forest inventory data andRemote Sensing. Then, to meet the needs of opinionrepresentation, we realize selecting and labeling directly on thescene with VRML and java. And then, to support collaborativegroup work, we integrate some methods in ComputerSupported Cooperative Work (CSCW) and CollaborativeVirtual Environment (CVE) and design three models:collaborative perception model, behavior model andcollaboration model. Finally, we introduce our prototypesystem: a virtual forest planning environment system for

people from all backgrounds, including public community,domain experts and government managers. Its proved that thecombination of VR, CSCW and RS technologies is a feasibleand innovative way to support forest management.

II. BACKGROUND OF OURPROJECT

In 2002, we started the project Study on DistributedVirtual Geographic Environments and Forestry RemoteSensing modeling funded by the Ministry of Science and

Technology of China (2002CCC01900). This project is aninterdisciplinarity study on how to integrate VR, GIS, RemoteSensing (RS), Artificial Intelligence (AI), CSCW andComputer Network technology to build a distributed virtualforest environment system. By this system we can not onlyvisualize the forest landscape from GIS and RS data, simulatethe developing procedure of a land stand, but alsocommunicate with each other inside the virtual landscapethrough an avatar embodiment.

The forest area we selected locates in Zhangpu district ofFujian province, China. With a forest cover rate of 60.52%,Fujian Province has the richest forest resource in south-eastchina. Local residents have taken good advantages of the forest

both in economic and ecological aspects for a long time, andnow that how to maintain a sustainable development and tablea reasonable management proposal are undoubtedly cared bythe government, domain experts and residents as well. This

project aims at providing those people with a on the spot

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virtual communication platform. The target area is 8.75kilometers wide and 11.425 kilometers long, as figure 1 shows.GIS and RS data we gathered are as follows:

Figure 1. The target area in Zhangpu District, Fujian Province, China

DEM data, resolution 25m (ArcInfo DEM format);

1:50000 digital vector map (ArcInfo Shapefile format); 1:10000 forest stand map (ArcInfo Shapefile format);

Forest investigation data (Oracle 9i table format);

RS image data (TIFF).

III. CONSTRUCTION OF VISUAL FOREST ENVIRONMENT

The main functions of our collaborative visual forestenvironment system and their solutions are listed in table 1.

TABLE I. COLLABORATIVE VFE FUNCTIONS AND THEIRSOLUTIONS

Function solution3D modeling Multigen Creator, VRML, ArcGISrendering Cortona VRML Clientselect and label touch sensor, VRML EAI

collaborative perception declare and subscribe, Agent behavior collision detection, route planningcollaboration 3D Electronic Whiteboard, MAS,

FIPA , ACL

A. 3D modeling and real-time rendering

Landscape can be understood usually as composed of sixessential elements: landform, vegetation, water, structures,

animals (including human) and atmosphere[6]. The first twowill be discussed here. In the field of forest landscapemodeling, many popular tools are available, such as MultigenCreator, 3DMAX, CosmoWorld, VRMLPad, Cult3D, etc.,however, different tools often use different file formats whichare not totally convertible to each other, so a more universalmodeling language is preferred. VRML is a high performancelanguage for 3D visualization on the world wide web, and mostkinds of 3D modeling software support exporting VRMLformat files. VRML1.0 was introduced in 1994 and VRML2.0,a version with more dynamic and interactive functions was

made in 1996, defined as more nodes as Transfer, Light,Viewpoint, Texture, Sensor, LOD, Fog, Sound, etc. The nextgeneration of VRML is X3D, an XML-compliant language thatwill be much more widely accepted. Some forest landscapevisualization or simulation applications have adopted VRMLas their modeling language [7]. Because it is widely used,especially in web-based applications, we choose VRML as themodeling language for the VFE.

We resort to Multigen Creator (version 3.5.1), a powerful3D modeling software, to build the landform model. Firstly weconvert ArcInfo DEM data to USGS DEM format by editingsome fields in the file directly, since both of them are text fileand they are very similar; then we convert USGS DEM file toMultigen DED (Digital Elevation Data) format using thereadusgs model of Creator; the third step is to choose aalgorithm to rebuild terrain surface from DED, such asPolymesh, Delaunay, CAT or TCT, after that, we get standardMultigen Creator model file - OpenFlight file; now in step fourwe can take the advantage of Creator to map the terrain withtexture of RS orthograph image, create LODs, divide the wholeterrain into several AOIs (Area of Interest); the last step is to

export to VRML file.

Vegetations (mainly trees) modeling is a little bit differentbecause the distribution of trees is dynamically developing, notas fix as the terrain. GIS data can be updated from time to timethrough RS, on-the-spot investigation and other means, somany famous forest visualization software, like IMAGIS [2],support building vegetation model from land use map. In this

project we consider two conditions: offline construction andonline construction. In most cases we use offline constructionto pre-build the forest model to alleviate the real time rendering

burden, while online construction usually used for simulationon the given hypothesis of users, such as predicting what thestand will be five years later according to a stand growth

model. Parallel Graphicss two products - Cortona SoftwareDevelopment Kit (SDK) and Cortona VRML Client as well asits External Authorize Interface (EAI) were used respectivelyto develop offline construction program in VB and onlineconstruction program in Java. The process of construct a landstand from GIS vector data can be divided into two steps:firstly construct the individual tree model, and secondly plantthe model in the stand region. A very popular method ofindividual tree modeling is mapping a real trees transparentimage on two planes[7][8]. We create an olive model by thismethod as figure 2 shows. To distribute trees on a stand region,we use horizontal parallel lines with specific interval tointersect with the polygon of forest stand boundaries, theninterpolate the inner points.

Figure 2. Mapping a real olive trees transparent image on two planes.

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Real time rendering is essential in collaborative VFE, inthis project we leave it to Cosmo VRML Client a ActiveX

plug-in running in Microsoft IE. What we can do to improvethe rendering speed is to design efficient models, such as using

LOD, as mentioned above.

B. Collaboration model

Select is an important means to interact with theenvironment. Considering the various kinds of users, we onlydeal with the 2D mouse select mode. Unlike in 2D UI, select in3D VFE environment is a little bit complex. Mouse pointermoving on the screen in a 3D environment can be consideredin a camera coordinate system with origin at the viewpointand z axis pointing to the mouse pointer, then the mouse

pointer have a 3D coordinate (x, y, d), d is the minimize depthof all intersections on the direction of z axis. Suppose the

pointed points coordinate in the world coordinate system is(X, Y, Z), deviation vector is (X0, Y0, Z0), then (X, Y, Z) can

be calculated by:

(X, Y, Z)T = M (x, y, d) T + (X0, Y0, Z0) (1)

Here M is the rotation matrix between the two coordinatesystems. In VRML2.0, several pointing sensors are defined to

support interaction with the model, such as TouchSensor,SphereSensor, PlaneSensor, CylinderSensor, When they are

activated, they can perform the above calculation and send outan event with the event description and the (X, Y, Z)

coordinate of the target point. We put TouchSensors on objectsand customize a java class based on VRML EAI to capture and

handle those events.

Label is necessary in CVGE, as illustrated in section three,

since its an intuitive manner to express ones opinion. Till

now, we support three kinds of labels: text, polyline, andsymbol. Text is used for comment and annotation, polyline isused for sketch out a region, and a symbol is usually a tree

model that can be placed on a clicked mouse point. Figure 3shows labeling tree models and text directly on the terrain.

Figure 3. Labeling tree models and text on the terrain.

C. collaborative perception model

Collaborative perception ability in CVGE includes threeW Where, Who and What, that is, in what condition thatone can detect others existence as well as their status. Themost famous model of awareness in a multi-user environment

is Benfords spatial model[9]. This spatial model defines fourkey concepts: aura, focus, nimbus and adapter, for allowing

objects to establish and control interactions. Agent is ahardware or (more usually) software-based computer systemthat enjoys the following properties: autonomy, social ability,reactivity, pro activeness[10]. In this project, we use anAgent-Avatar pair to partly implement Benfords spatial

model, that is, aura and nimbus, by the mechanism of declareand subscribe. Further more, we extend the aura and nimbus

concepts from spatial dimensions to organization dimension inorder to define whom you interest in. For each avatar, we

define an Agent object for it, so before he logs in theenvironment, the agent will prompt him to define his aura (the

potential area where others may detect you, such as specifyinga radius; the potential people who may detect you) and nimbus

(the field of view; who are you interest in), then after his login,the agent will declare his aura and subscribe his nimbus for the

server. When the aura and nimbus intersect in both spatial andorganization dimension, perception event will take place.

D. Behavior model

Headings, or heads, are organizational devices that guidethe reader through your paper. There are two types: componentheads and text heads.

In most cases, behaviors of avatars in CVGE, such as walk,fly, sending message, etc., are controlled manually by theusers, however, some behaviors request the computer toautomatically perform some tasks or to guarantee their

rationality, then behavior model is designed to fulfill that. Inthis project we implement a walk behavior model in the Agent.There are two modes of walk on the terrain: one is totallynavigated by mouse or keyboard and the other is given adestination point or a few key points. In the former mode, toavoid colliding with the terrain or floating in the air, the Agentis designed to calculate the elevation value of each point in theroute and adjust the elevation of the avatar to this value on realtime. Since we have divided the whole terrain into 182IndexedFaceSet (a node in VRML2.0), and created indexes tothem by recording their boundaries, so the elevation calculationis timesaving.

In the second mode, the Agent needs to perform a route

planning from current position to the destination. Route planning in forest environment is very complex, sometimeseven impossible to realize since roads are very limited in forest.Till now we just interpolate middle points along the direct linewith fixed interval. It may be not accurate but really verysimple and easy to understand.

E. Collaboration model

In CSCW, collaboration is divided into four modes: sametime and same place, same time and different place, differenttime and same place, different time and different place. Among

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these, the different time and same place mode is an efficientonline collaboration method. In CSCW, Electronic Whiteboardis a widely used collaboration model, so in this project weextend this model to 3D Electronic Whiteboard model.Essentially, the 3D Electronic Whiteboard is part of the wholeVFE which can be shared by the relevant people in the sameregion. The communication control is implemented by themechanism of declaring and subscription: commonly only

ones working status is declared and published to others, andthe labeling processes or labeling results are shared only if theyare subscribed, thus, to avoid confliction between labels fromdifferent people, people usually subscribe one labeling processat one time.

Communications between distributed users in collaborativeenvironment has been realized by many means, such as DISinfrastructure[11], HLA infrastructure and directly TCP/IP. Infact, Multi-Agent System (MAS) has its own standards tofacilitate Agent communication. One of the most importantstandards is FIPA (Foundation for Intelligent Physical Agents).Unlike all the above solutions, FIPA use an AgentCommunication Language (ACL) to express the collaboration

messages[12]. The FIPA ACL specifies communicationmessages between Agents and has an associated formalsemantics. FIPA-compliant MAS platform makes us free from

bottom-level communication design and to concentrate onsemantic-level design. In this project, we use an open Agent

building environment- JADE (Java Agent DevelopmentEnvironment) which implements most FIPA specifications,such as MTS (Message Transport Service), AMS (AgentManagement System) and DF (Directory Facilitator), then therest we should do is to construct the ACL message content(Figure 4).

Figure 4. The architecture of the Agent communication system which

implements most FIPA specifications such as MTS, AMS and DF.

IV. DISCUSSIONS

Virtual Reality is a computer graphic world that looks likereal, listens like real and touches like real , so realism is animportant criterion for the usability of collaborative VFE.Texture mapping is believed to be an efficient way to expressthe detail of objects and make models more verisimilar, so wetake photos on many species of trees like olive, pine, litchi and

mango which make them really easy to recognize andtimesaving to render. However, photos can only represent thecurrent status of trees, while it is helpless for simulating whatthe forest will look like a few years later. So in many cases, weneed to seek a balance between looks like and acts like [6].In face, we have developed a stand-along program in VisualC++ to generate tree models by giving geometry parameters ofthe trunk, brunches, and leaves, we also have established a treegrowth model base which records such parameters of differenttrees in different age. Thus, when given the tree species and itsage, the 3D tree model can be calculated out quickly.Compared with the model like Figure 2, this kind of modelconsists of much more polygons (about a few thousands), soits rather suitable to construct a local area stand than a large

area of forest, and it also may not look so verisimilar, but it hasthe virtue of flexibility to change. The next step is to integratethis stand-along function into the web-based collaborative VFEapplication.

V. REFERENCES

[1] De Reffye, P., Edelin, C., Francon, J., Jaeger, M., Puech, C., 1988, Plantmodels faithful to botanical structure and development. ComputerGraph, 22, pp. 151158.

[2] Perrin, L., Beauvais, N., Puppo, M., 2001, Procedural landscapemodeling with geographic information: the IMAGIS approach.Landscape and Urban Planning, 54, pp. 3347.

[3] Orland, B., Radja, P., Su, W., 1994, Smart Forest: an interactive forest

data modeling and visualization tool. In Proceedings of the Fifth ForestService Remote Sensing Applications Conference, Salt Lake City, Utah,US, pp. 283-292.

[4] Orland, B., 1997, Smart Forest-II: Forest Visual Modeling for ForestPest Management and Planning. http://www.imlab.psu.edu/smartforest

[5] Mingyao Qi, Tianhe Chi, et al. Public Participation Virtual GeographicEnvironment: A Study on Vritual Forest Envrionment. In proceedings ofInternational Conference on Virtual Geographic Environment andGeocollaboration, Hongkong, 15-16 Dec., 2003.

[6] Ervin S.M., Digital landscape modeling and visualization: a researchagenda. Landscape and Urban Planning, 54, pp. 49-62.

[7] Lim, En-Mi, Honjo, T., 2003, Three-dimensional visualization forest oflandscapes by VRML. Landscape and Urban Planning 63 pp. 175-186.

[8] Muhar A., 2001, Three-dimensional modeling and visualization ofvegetation for landscape simulation. Landscape and Urban Planning, 54

pp. 5-17.[9] [9] S. Benford, L. Fahln, A Spatial Model of Interaction in Large Virtual

Environments, In Proceedings of ECSCW93, Milan, Italy, September1993, pp. 13-17 .

[10] [10] M. Wooldridge, N. R. Jennings, Intelligent Agents: theory andpractice, Knowledge Engineering Review, 10:2, pp. 115-152.

[11] [11] M. R. Stytz, S. B. Banks, W. D. Wells, Towards realizingcooperative distributed workspaces for distributed virtual environments,In Proceedings of Intelligent Information Systems, pp. 545 -549.

[12] [12]Mingyao Qi, Tianhe Chi, Guang Shu, Agent based multi-userinteraction in Geo-DVE, Proceedings of the International Conference onActive Media Technology, 2003, pp 259-264.

Agent Management

System

Directory

Facilitator

Message Transport Service



User Agent

ACL ACL

ACL ACL


User Agent


User Agent


User Agent

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Using Virtual Forest Environment on Collaborative Forest Management