The Compilation of 2D and 3D Dynamic Visualizations

Brian Farrimond

and Ella Pereira

Edge Hill University, St Helens Road, Ormskirk, U.K.

Keywords: 3D Modelling, Parametric Modelling, Information Visualization, Temporal Database, Digital Heritage,

Industrial Heritage, Cultural Heritage.

Abstract: 3D modelling and visualization are rapidly developing in power and application. Unfortunately they are also

developing in complexity of use. They require considerable practice and skill in order to model and visualize

successfully. This paper presents modelling and visualization strategies and tools based on textual

descriptions of models and visualizations. The principles of compilation used in coding for many decades are

applied to modelling and visualization. This results in tools able to model and visualize many types of dynamic

object such as ships and locomotives that can be used successfully by non-expert users who have knowledge

of the objects being modelled. The tools have been used in local primary schools since 2007.

1 INTRODUCTION

As the uses of 3D models increase, more and more

tools become available to build and make use of them.

Unfortunately as the tools continue to be developed,

so their complexity and difficulty of use increase.

Several products aim to simplify the model building

process but they still require a certain amount of skill

and experience to create successfully realistic models

of objects such as buildings, ships and steam

locomotives. In this paper we present our solutions

for making easier the creation and use of 3D models

for use in visualizations of highly deterministic

historical events whose actions follow pre-

determined rules such as the movements of railway

trains and shipping.

Our model building tools are inspired by the

compiling methodologies developed since the 1940s

and 1950s to remove the need for the programmers to

understand the architecture of the computers they

were coding for. They introduced high level

languages such as FORTRAN (Backus, 1978) and

compilers that translate them into machine code. We

aim to remove from the user the need to understand

how geometrical primitives can be assembled to

model real world objects. Similarly, by focussing on

highly deterministic scenarios we are able to direct

the computer with a few narrative sentences to carry

https://orcid.org/0000-0001-7606-6899

https://orcid.org/0000-0001-7273-3295

out the computations animating the complex

movements of railway trains and ships.

This paper describes strategies that enable non-

expert users to create rapidly complex visualizations

containing accurate models of dynamic, animated

artifacts compiled from textual information. The

strategies are based on textual descriptions which

lend themselves to embedding into model creation

and usage the capture and provision of textual

information about the objects being modelled.

Conversely, the strategies make possible the

automatic generation of models from textual

descriptions in other, well-formed formats by

conversion into our formats. The strong links between

models, visualizations and the underpinning text offer

rich opportunities for enhancing the application of 3D

modelling to industrial heritage.

Tools based on these strategies have been

developed and used successfully in a group of

primary schools in the United Kingdom since 2007.

Children, between 9 and 11 years old, have been able

to build complex, dynamic 3D models while learning

about the terminology and grammar of the real-world

objects that the models represent such as churches,

steam locomotives and paddle steamers.

Collaboration continues with an industrial

heritage society on the development of visualizations

to enhance the society’s outreach to schools and the

general public.

150

Farrimond, B. and Pereira, E.

The Compilation of 2D and 3D Dynamic Visualizations.

DOI: 10.5220/0011633300003417

In Proceedings of the 18th International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications (VISIGRAPP 2023) - Volume 3: IVAPP, pages

150-157

ISBN: 978-989-758-634-7; ISSN: 2184-4321

 2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)

2 RELATED WORK

3D models are normally created with powerful and

complex 3D modelling tools. Ugwitz et al discuss the

tools and their usage by their students for the

modelling of historical buildings (Ugwitz et al, 2021).

They include commercial tools such as Autodesk

Maya, Autodesk 3D Studio Max and free tools such

as Blender. They also include 3D game engines

(Unity, Unreal, CryEngine). The learning curves of

all the software are considerable and natural ability is

required for success in building more complex

models from geometrical primitives such as curves,

cuboids, spheres, cones and extrusions. This is

evidenced by the official and unofficial tutorial

videos available on the internet (Autodesk 3ds Max

Learning Channel, 2022) (Blender Tutorials, 2022).

3D sculpting tools such as zBrush aim to provide

a more intuitive way of building but the interfaces are

still technical and require considerable familiarity

with the dozens of tools/brushes available in order to

create realistic models. (zBrush, 2021). They rely. on

the user having a traditional sculptor's skills

3D model building from 2D drawings is available

in tools such as Sketchup but, again, considerable

skill is required for success or the contribution to a

model of a locomotive or a ship is very limited

(Sketchup, 2021).

3D Parametric Modelling has been developed in

recent years to increase the connectivity between

components enabling consistent changes to be

applied throughout a model automatically. This is

implemented either as extensions to the 3D modelling

tool (such as in Maya) or as plug-ins (such as

Grasshopper for the Rhinoceros 3D modelling tool

(Rhino 3D, 2022)). Networks of relationships

between nodes are created. Components attached to

the nodes are able to receive input values and send

output values to other connected nodes. Thus any

changes in a parameter triggers a cascade of output

values to be sent through the network updating the

state of the components as determined by the network

design. The networks are created by either graphical

programming or scripting. Considerable experience is

required in order to produce successful networks. The

networks can be extremely complex.

The advantages of modelling with real world

components such as windows, walls and doors have

been recognised by the construction industry which

has seen the introduction of Building Information

Modelling (BIM). The objects to be added to a

building, such as windows and doors are selected

from databases of “smart” objects. Once inserted, the

dimensions of the objects can be modified.

Parametric modelling within BIM enables rules to be

applied such as setting the difference in height

between floor and ceiling equal to the height of the

walls – or vice versa. This can be achieved by the use

of scripting for example (Casini, 2022).

Many applications have been developed exploring

the use of natural language to generate visual

interpretations of semantic content either as static

scenes or dynamic animations (Hassani et al, 2017).

We use our models in visualizations generated from

two types of source: restricted natural language

narratives and transcribed timetables. The

deterministic nature of our chosen scenarios and the

embedding of behaviour in the semantics of the

models such as the operation of lock gates and swing

bridges in a harbour means that only a few dozen

sentence types are needed to create realistic scenarios.

We make use of regular expressions to parse the

narratives.

3 OUR APPROACH

Our tools for building and using 3D models aim to be

easy to learn for the non-expert because:

• they deal entirely with real world terms (such as

nave, chancel, transept for a church, firebox,

boiler and wheels for a steam locomotive) when

adding and modifying components and no

knowledge of how a 3D tool would render them

is needed. The software knows how to do that.

• building consists of selecting a component in a

model, customising it by modifying the attributes

displayed in a table and adding components to

the selected component and moving on to select

these added components to customise their

attributes. No switching of tools is required. The

procedure is taught to primary school children in

a matter of minutes.

In our software, parametric modelling is coded

within the model builder libraries. The user does not

have to specify the connectivity between

components; it is embedded within the library code.

The code uses the attributes of the modelled

components to determine the geometry and their

effects on other components within the model. For

example, if the height of the saddle supporting the

smoke box on a steam locomotive is raised then the

code changes the height of the saddle geometry; it

also raises the position of the smoke box to conform

and raises the heights of the boiler and firebox to

conform in turn. Thus the changes to one parameter

of the model cascade through all the other

components affected by the change. Unlike the

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parametric modelling described in the previous

section, all the coding necessary to achieve this

component connectivity is embedded in the model

building libraries.

This means that our model builders are not general

purpose model builders. They can only build the types

of model targeted by the builder libraries. However,

we believe that this is worthwhile doing because an

important and interesting group of visualizations can

be created with them. At present we are exploring the

visualization of railway and shipping movements and

the creation of landscapes of medieval churches and

cathedrals. In the real world each domain contains (or

contained) many thousands of variations of the same

kinds of things – locomotives, carriages, wagons,

railway infrastructure such as signals and track and

churches. Our builder tools are suitable to model

these.

The arrangements to animate items such as

locomotives and carriages are embedded in the library

code and the results seen in animated visualizations.

4 2D AND 3D COMPILATION

Our modelling strategy is based on compiling 3D

models from formal textual descriptions. These

models are used in complex 3D visualizations

compiled from textual sources including restricted

natural language narratives and transcribed

timetables.

The aim is to enable the user to work entirely in

terms of his domain rather than the artifacts of 3D

modelling tools. For example, a church should be

built from naves, chancels, windows etc and not

cuboids, spheres and cones. Not many people have

the skills to look at an object like a church or ship and

be able to split it into the geometrical primitives

needed to model it. Our tools aim to prevent this from

being a hindrance to modelling and to provide an

environment in which the users will feel familiar with

the components they are using to build.

The text based methodology of the tools provides

candidate methods for recording information about

objects textually in an unambiguous, structured

manner that can be automatically visualized, for

example, for validation purposes.

Additionally, any existing textual descriptions

containing sufficient information can be converted

into our text formats and automatically visualized in

2D and 3D.

5 OVERALL VISUALIZATION

COMPILATION SYSTEM

The overall system for making 3D models and using

them to create and view visualizations, which we

refer to as scenarios, is shown in Figure 1:

Figure 1: Overall system for creating dynamic 3D models

and using them in visualizations. Builders include Carriage

Builder, Locomotive Builder, ScenarioScene Builder

(which creates the scenery and railway and dock

infrastructure)…

This is a development of our earlier work visualizing

historical events (Presland et al, 2010), (Hazlewood

et al, 2011). 3D models are created by adding and

customising the components from which they are

made, e.g. ship’s hull, masts, rudders. The models are

dynamic in the sense that they have moving parts such

as ships having rudders that are able to swing left and

right and locomotives having wheels that are able to

turn. The attributes of the customised components are

recorded in the model definition file.

The models are added to a library that is used by

a visualization compiler that reads a narrative or

timetable that determines what is to happen in a

visualization. The visualization compiler identifies

the models required from the library, loads them and

uses their characteristics to determine state of the

models within the scene as the visualization

progresses through its time span.

The visualization is saved as a set of VRML or

OBJ files and text files storing the scene graph for the

visualization and keyframes containing the state of

the nodes of the scene graph at one second intervals.

The stored visualization includes:

• The scene graph – specifying each node in the

scene graph and its connectivity to the other

nodes. It also contains the links identifying which

dynamic nodes are driven by other nodes and the

function and parameters to be used when updating

a driven node in the light of changes to a driver

node. (See Section 8.1)

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• The keyframe table – specifying the state of each

transform node for each second of the

visualization time span.

The mechanism we use to save a visualization

enables us to use the same saved visualizations in any

implementation of a scenario viewer. The viewer

must be able to read the saved scene graph description

and generate the corresponding scene graph in its own

environment. The viewer must be able to load the

keyframe values. So far we have implemented

viewers using Java 3D (Java is the implementation

language of our builder software) and in Unity 3D.

The Unity 3D viewer has been exported for use in the

Edge Hill University’s Computer Augmented Virtual

Environment (CAVE) and Vive headsets using

MiddleVR (MiddleVR, 2022) to interface to the

hardware. It should be possible to create a viewer in

any 3D environment that can create, display and

manipulate the nodes of a scene graph.

Primary school children build locomotive models

in class then come to see them running in the CAVE

and in the Vive headsets at Edge Hill University

where they are embedded into a model of the local

railway system of 100 years ago.

6 BUILDING MODELS USING

THE MODEL BUILDERS

The objects we have modelled so far, include sailing

ships, paddle steamers, steam locomotives, railway

carriages and wagons and beam engines and scenario

scenes containing harbours and railway networks,

churches and cathedrals.

In all cases we have failed to find useful existing

written descriptions that could be transformed

directly into the XML model definitions that we are

making use of. Consequently we realised that we

needed to create interfaces that enable the user to

create the textual descriptions for the model builders,

building the models by adding components and

customising their attributes using whatever

information is available.

The interfaces consist of 3 panels: the component

tree, a table showing the attributes of the selected

component and the 3D view as shown in Figure 2:

A 2D view is also available for locomotives as

shown in Figure 3.

Figure 2: Locomotive Builder interface. The 3D view is on

the right. The user selects components in the component

tree at top left. The user edits the selected component

attributes at bottom left. Clicking on the Update button

refreshes the 3D model.

Figure 3: The same locomotive (Lancashire & Yorkshire

Railway Class 1400) shown in the 2D view. Components

may be selected by clicking on them in this view. Here, the

dome is currently selected (highlighted in red) with its

attributes shown in the lower left panel.

When a model definition file is opened the model type

is detected and the corresponding model builder

library is used to read in the file and generate the

corresponding VRML 3D model files specifying the

vertices and polygons forming the 3D geometry.

When the model is edited, updates cause the

VRML code for the model to be regenerated. This

repeated VRML code writing has caused no delay

problems with objects such as locomotives. This

holds true even for the older, less powerful machines

available in primary schools. However, it is

recognised that optimisation or an alternative method

will be needed in order to achieve satisfactory

performance for models as large as full cathedrals.

Selecting components for editing is handled by

selecting them in the component tree or in the 2D

views.

It has been found that the process of obtaining

measurements from drawings of steam locomotives,

for example, is much simplified if model editing is

carried out in a 2D view in which images of the

original drawing are placed in the background.

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It has been found that modelling scenes that

include docks and railways is best done principally in

2D using images of 25 inch to the mile Ordnance

Survey maps (National Library of Scotland, 2022).

Scenario scenes such as the Liverpool docks are

modelled in the 2D view as shown in Figure 4:

Figure 4: Editing the Albert Dock in Liverpool from the

1906 25 inch to the mile Ordnance Survey Map. A jetty is

shown selected in red. Map from National Library of

Scotland.

Figure 5 shows a selection of other models: created

with the builder tools.

7 CREATING THE MODEL

BUILDERS

A set of model builders have been developed that can

read high-level language model definitions and

generate corresponding 2D images and 3D models. A

consistent structure underlies the builders for

different types of model. Consequently, much of the

creation of the model builders is automated. This

speeds up development and makes modifications to

the builders easier and quicker to implement.

The model builders are created using a builder

compiler that reads a definition of the grammar to be

used to describe a model and generates an application

library that is able to generate 2D images and 3D

models expressed in the VRML and OBJ formats

from model definitions written using the grammar.

8 COMPILING DYNAMIC

VISUALIZATIONS

The models created as described above are used

inside dynamic visualizations. The models are

exported to a model library from where they can be

included in the visualizations.

Figure 5: Examples of model types created by our model

builders - a Lancashire & Yorkshire Railway carriage, a

schooner, a scenario scene model of Liverpool Docks, a

signal box and a quadripartite cathedral vault.

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The export includes the collection of VRML and

OBJ files that realise the dynamic 3D model along

with the data files that contain a definition of the

model’s scene graph recording how moving sub-

components are to be attached to a visualization scene

graph and any lookup tables used by the model.

8.1 Model Animation

Models are animated by putting the moving

component VRML or OBJ code into separate files

and loading them into the model’s scene graph

attached to appropriate transform (translation,

rotation and scaling) nodes. During animated

visualization the values of the transform nodes are

continually updated producing the desired animation.

Figure 6: Part of the scene graph for a stern wheeler paddle

steamer showing the transform nodes (T_RY translation

and rotation about Y axis, T translation, RX rotation about

X axis). Node [1] drives nodes [4] and [7]. This means that

the changed value of the RX attribute for node [1] (which

controls the turning of the wheel) is sent to nodes [4] and

[7] where the value is used in the function reciprocal to

modify their RX values and so animate the connecting rods

as the wheel turns. Lookup tables are used for more

complex mechanisms such as Walschaert’s valve gear and

Watt’s parallel motion.

Figure 6 shows the part of a scenario scene graph for

a stern wheeler paddle steamer and showing how

certain nodes are driven by other nodes to realise the

animation.

8.2 Visualization Animation

The visualizations are created by a visualization

compiler. Limited natural English narratives and

transcribed railway timetables are processed to

populate a temporal database. The narratives contain

sentences such as

Train train999 consists of Loco 1400, 2 * carriage

D30, carriage D33.

Train999 is initially parked at Mark4 back

towards Mark3.

Train999 moves to Mark5 facing south at speed

10 mph at 6:04 am

Figure 7 shows a passenger train in a visualization

of the operation of the Lancashire & Yorkshire

railway (LYR) around the year 1905.

Figure 7: Lancashire & Yorkshire Railway (LYR)

locomotive with train in the early 1900s in 3D

visualization.

The path and timings followed by trains and ships are

deduced from the narrative and the operating

characteristics of the trains and ships.

The visualizations are built “offline” using

mathematical models of the motions of trains and

ships. For example, the attributes of the models such

as the tractive effort of steam locomotives and their

weight are used to determine the accelerations of

trains. The mathematical model solutions for location

and heading etc of the trains as they move are

determined at 1 second intervals as the scenario time

progresses. The track paths are identified in the

scenario scene models that contain the track and other

railway infrastructure and buildings embedded in the

landscape. The values are recorded in the keyframe

files as the values of parent transform nodes for the

model locomotives and carriages in the scenario

scene graph.

The keyframe values for nodes within part of the

scene graph for each locomotive and carriage are

determined by deductive modelling. If, for example,

a train is running between two places starting at a

given time and ending at a given time, we determine

the path followed from the track graph. In the simple

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155

case, omitting speed restrictions along the path, we

determine the train’s location at each second of its

journey along that path by applying the equations of

motion to the train accelerating, travelling at constant

speed then decelerating to its destination. From these

locations we can deduce the amount of rotation of a

locomotive’s wheels every second along the journey.

From the rotation of the driving wheels we can

determine the location of the attached coupling rods,

connecting rods and valve gear. The values for the

transform nodes for these locomotive components

can then be deduced and recorded in the keyframe

table.

When the visualization is run, on each tick of the

clock, the viewer determines the values to be assigned

to each transform node by interpolation in the table of

keyframes. An exception to this is those actions such

as the recoil of a naval gun whose motion cannot be

adequately modelled by the interpolation of time

points at 1 second intervals. In these cases the current

values of the relevant scene graph transform nodes

are found by running their mathematical models at

that moment in the visualization run. Apart from

interpolation and the use of functions for driven nodes

as shown in Figure 6, all the other model state

calculations are done during the compilation of the

keyframe tables. This means that simulations of, for

example, 6 or more trains can run in a landscape

simultaneously in not very powerful PCs such as

found in a primary school. The realism is open to

further improvement as time permits by using more

sophisticated mathematical models to compute the

transform node values. The effect of changing the

time step from 1 second should also be explored.

8.3 Dynamic 2D and 3D Visualizations

from Railway Timetables

A collaboration of members of the Lancashire &

Yorkshire Railway Society has transcribed the UK

Bradshaw railway passenger timetables of 1906 for

the Lancashire & Yorkshire Railway Company

(LYR). The Society has also transcribed the goods

trains workings of 1920. The visualization compiler

has been modified to read these transcriptions and

display 2D animations of them online (LYR Society,

2016). The visualization compiler enables

transcribers to validate their transcriptions by

identifying wrong timings revealed, for example, by

resulting in impossible speeds. Figure 8 shows the

visualization.

Figure 8: 2D animation of Bradshaw 1906 Passenger

Timetable for the Lancashire & Yorkshire Railway

Company.

A prototype online 3D simulation of the timetable

is being developed. The simulation divides the area

served by the Lancashire & Yorkshire Railway into

1-kilometre squares. The prototype covers 24 square

kilometres and includes three stations and the railway

lines joining them – the same region covered by the

model used by the children to run their trains. Each

scheduled train has its scene graph and keyframes

held in an online database to be downloaded on

demand and added to the viewer’s scene graph as

viewing place and time determine.

Future work will include implementing the

simulation on mobile devices so that a “window into

the past” can be created through which visualizations

of historical locations and events can be viewed at the

user’s current location.

9 EVALUATION

As the tools have been developed they have been used

by children aged between 9 and 11 in local primary

schools.

Figure 9: Heavily fortified church built by 10-year-old Luke

and Abby by the end of the morning session.

Our trials with the first standalone, church

building application took place in 2007. They are

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repeated each year by popular demand. The children

learn the structure of churches whose components

include nave, chancel, transepts etc. They then learn

how to use the modelling tool. By the end of the single

morning session they were able to build models

churches as shown in Figure 9:

The children provide an enthusiastic audience and

the activity fits naturally into the curriculum. Church

building has been done from 2007 to the present day

for about 60 children per year.

Building and running locomotives is also popular

and take a day. In the morning the children learn how

steam locomotives work and what the various

components do and how they fit together. They learn

how to use the locomotive model builder and build a

locomotive from a set of measurements (some of

which they made themselves) on simplified

engineering drawings. This has been done, apart from

Covid, for about 60 children per year for 10 years.

In the afternoon the children modify and compile

visualizations and export them to the Unity 3D viewer

to run their locomotives pulling trains on models of

the 1906 railway system in the local area. They learn

how to drive a steam locomotive and run the

locomotives under manual control.

The children have also built and sailed model

paddle steamers around the Liverpool docks by

modifying narrative visualizations and under manual

control.

10 CONCLUSIONS

The model and visualization builders have

demonstrated that it is possible to enable non-

specialist users such as primary school children to

create 3D models and use them in complex, realistic

3D visualizations in a range of viewing environments.

The lack of existing, suitable textual descriptions of

the objects being modelled has been surprising but

this methodology offers tools that make the creation

of such descriptions practical and useful.

The compilation of 3D models from their

component attributes has been applied successfully to

a range of different model types including ships,

locomotives, carriages, beam engines and scenes with

railway networks. Their creation from given

measurements or from invention has been achieved

successfully by hundreds of primary school children

for over 15 years.

Deductive modelling has enabled compilation of

restricted natural language narratives and transcribed

timetables to create complex visualizations on PC,

CAVE and Vive headsets. Improvements in

visualization quality as 3D rendering develops can be

easily applied to legacy visualizations by simple re-

compilation.

The work on developing tools to build a full

online animated model of the Lancashire & Yorkshire

Railway mentioned in Section 8.3 will be generalised

to the exploration of the modelling of other past

worlds such as pre-Reformation England.

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